Animated Science – A Science & Charcuterie Blog



09 Electric Circuits338?minutes338?marksQ1.(a)???? A resistor is a component that is used in an electric circuit.?(i)??????Describe how a student would use the circuit to take the readings necessary to determine the resistance of resistor?R.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(6)(ii)?????Explain why the student should open the switch after each reading.................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(iii)????In an experiment using this circuit, an ammeter reading was 0.75 A.The calculated value of the resistance of resistor?R?was 16 ?.What is the voltmeter reading?Use the correct equation from?Section C?of the Physics Equations Sheet.................................................................................................................................................................................................................................Voltmeter reading = ................................ V(2)(iv)????The student told his teacher that the resistance of resistor?R?was 16 ?.The teacher explained that the resistors used could only have one of the following values of resistance.??10 ?12 ?15 ?18 ?22 ?Suggest which of these resistors the student had used in his experiment.Give a reason for your answer.................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)???? The diagram shows a fuse.?Describe the action of the fuse in a circuit.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(Total 15 marks)Q2.Electrical circuits have resistance.(a)???? Draw a ring around the correct answer to complete the sentence.??When the resistance of a circuit increases, the current in the circuitdecreases.increases.stays the same.(1)(b)???? Use the correct answer from the box to complete each sentence.??a filament bulban LEDan LDRAn electrical component which has a resistance that increases as thetemperature increases is .................................................. .An electrical component which emits light only when a current flows through itin the forward direction is .................................................. .(2)(c)???? When some metals are heated the resistance of the metal changes.The equipment for investigating how the resistance of a metal changes when it is heated is shown in the diagram.??In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.Describe an investigation a student could do to find how the resistance of a metal sample varies with temperature. The student uses the equipment shown.Include in your answer:?????????how the student should use the equipment?????????the measurements the student should make?????????how the student should use these measurements to determine the resistance?????????how to make sure the results are valid...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(6)(d)???? The table shows some data for samples of four metals?P,?Q,?R?and?S.The metal samples all had the same cross-sectional area and were the same length.??Metal sampleResistance at 0°Cin ohmsResistance at 100°Cin ohms?P4.055.67?Q2.653.48?R6.09.17?S1.702.23A graph of the results for one of the metal samples is shown.???????? ??????? Temperature in °C(i)??????Which metal sample,?P,?Q,?R?or?S, has the data shown in the graph?????(1)(ii)?????One of the results is anomalous. Circle this result on the graph.(1)(iii)????Suggest a reason for the anomalous result.................................................................................................................................................................................................................................(1)(iv)????The same equipment used in the investigation could be used as a thermometer known as a ‘resistance thermometer.’??Suggest?two?disadvantages of using this equipment as a thermometer compared to a liquid-in-glass thermometer.1 .............................................................................................................................................................................................................................2 .............................................................................................................................................................................................................................(2)(Total 14 marks)Q3.(a)????The diagram shows the inside of a three-pin plug.?(i)??????What name is given to the wire labelled?S?Draw a ring around the correct answer.??earthliveneutral(1)(ii)?????What is the colour of the insulation around the wire labelled?T?Draw a ring around the correct answer.??bluebrowngreen and yellow(1)(b) ????The plug contains a 13 amp fuse.(i)??????Which?one?of the following is the correct circuit symbol for a fuse?Draw a ring around the correct answer.?(1)(ii)?????The diagram shows the parts of the fuse.?What would happen if a current of 20 amps passed through the 13 amp fuse?..............................................................................................................................................................................................................................(1)(c) ????Not all electrical appliances are earthed.(i)??????Which?one?of the following appliances must be earthed?Tick ()?one?box.???Table lamp?Toaster?Hair straighteners?Give a reason for your answer...............................................................................................................................................................................................................................(2)(ii)?????Earthing an appliance helps to protect a person against a possible risk.What is the risk?...............................................................................................................(1)(d) ????The diagrams show how two lengths of mains electrical cable were joined. The individual wires have been twisted together and covered with insulating tape. This is not a safe way to join the cables.?What is the possible risk from joining the two lengths of mains electrical cable in this way?................................................................................................................................................................................................................................................(1)(e) ????The diagram below shows a connecting box being used to join two lengths of electrical cable. This is a safe way to join the cables.?The cable grips are important parts of the connecting box.Explain why.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 10 marks)Q4.(a)????The diagram shows the circuit used to obtain the data needed to plot the current–potential difference graph for a filament bulb.?(i)??????Why is the component labelled ‘J’ included in the circuit?..............................................................................................................................................................................................................................(1)(ii)?????The resistance of the bulb increases as the potential difference across the bulb increases. Why?..............................................................................................................................................................................................................................(1)(iii)????The bulb is at full brightness when the potential difference across the bulb is 12 V.?The current through the bulb is then 3 A.Calculate the power of the bulb when it is at full brightness and give the unit.Use the correct equation from the Physics Equations Sheet..............................................................................................................................................................................................................................................................................................................................................Power = ..................................................(3)(b) ????In this question you will be assessed on using good English, organising information clearly and using specialist terms where appropriate.The table gives data about two types of light bulb people may use in their homes.??Type of light bulbEnergy efficiencyCost of one light bulbAverage lifetime in hours?Halogen10%?1.952 000?Light Emitting Diode (LED)32%?11.7036 000Both types of light bulb produce the same amount of light.Evaluate, in terms of cost and energy efficiency, the use of the two types of light bulb.To gain full marks you must compare both types of light bulb and conclude which light bulb would be the best to use.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(6)(Total 11 marks)Q5.The picture shows an electric cooker hob. The simplified circuit diagram shows how the four heating elements connect to the mains electricity supply. The heating elements are identical.?When all four heating elements are switched on at full power the hob draws a current of 26 A from the 230 V mains electricity supply.(a) ????Calculate the resistance of one heating element when the hob is switched on at full power.Use the correct equation from the Physics Equations Sheet.Give your answer to 2 significant figures.........................................................................................................................................................................................................................................................................................................................................................................Resistance = .............................. Ω(3)(b) ????The table gives the maximum current that can safely pass through copper wires of different cross-sectional area.??Cross-sectional area in mm2Maximum safe current in amps?1.011.5?2.520.0?4.027.0?6.034.0(i)??????The power sockets in a home are wired to the mains electricity supply using cables containing 2.5 mm2?copper wires. Most electrical appliances are connected to the mains electricity supply by plugging them into a standard power socket.It would?not?be safe to connect the electric cooker hob to the mains electricity supply by plugging it into a standard power socket.Why?............................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(ii)?????Describe the structure of the cable that should be used to connect the electric cooker hob to the mains electricity supply.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c) ????Mains electricity is an alternating current supply. Batteries supply a direct current.What is the difference between an alternating current and a direct current?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 10 marks)Q6.(a)????Electrical circuits often contain resistors.The diagram shows?two?resistors joined in series.?Calculate the total resistance of the?two?resistors.........................................................................................................................Total resistance = .................................................. Ω(1)(b) ????A circuit was set up as shown in the diagram. The three resistors are identical.?(i)??????Calculate the reading on the voltmeter...............................................................................................................................................................................................................................Reading on voltmeter = .................................................. V(2)(ii)?????The same circuit has now been set up with two ammeters.?Draw a ring around the correct answer in the box to complete the sentence.???smaller than??The reading on ammeter?A2?will beequal tothe reading on ammeter?A1.??greater than?(1)(Total 4 marks)Q7.(a)????The diagram shows the information plate on an electric kettle. The kettle is plugged into the a.c. mains electricity supply.??230 V2760 W?50 Hz?Use the information from the plate to answer the following questions.(i)??????What is the frequency of the a.c. mains electricity supply?...............................................................................................................(1)(ii)?????What is the power of the electric kettle?...............................................................................................................(1)(b) ????To boil the water in the kettle, 2400 coulombs of charge pass through the heating element in 200 seconds.Calculate the current flowing through the heating element and give the unit.Use the correct equation from the Physics Equations Sheet.Choose the unit from the list below.??ampsvoltswatts........................................................................................................................................................................................................................................................................................................................................................................Current = ............................................................(3)(c) ????The amount of charge passing through the heating element of an electric kettle depends on the time the kettle is switched on.?What pattern links the amount of charge passing through the heating element and the time the kettle is switched on?................................................................................................................................................................................................................................................(2)(Total 7 marks)Q8.(a)???? A student set up the circuit shown in the diagram. The student uses the circuit to obtain the data needed to plot a current - potential difference graph for a diode.?(i)??????Draw, in the boxes, the circuit symbol for a diode and the circuit symbol for a variable resistor.??Diode?Variable resistor????????????(2)(ii)?????The student made two mistakes when setting up the circuit.What?two?mistakes did the student make?1 ...........................................................................................................................................................................................................................2 ...........................................................................................................................................................................................................................(2)(b) ????After correcting the circuit, the student obtained a set of data and plotted the graph below.?????????????????Potential difference in volts(i)??????At what potential difference did the diode start to conduct an electric current?...................................................................... V(1)(ii)?????Use data from the graph to calculate the resistance of the diode when the potential difference across the diode is 0.3 V.Use the correct equation from the Physics Equations Sheet..............................................................................................................................................................................................................................................................................................................................................Resistance = ......................... ohms(3)(c) ????The diagram shows the trace produced by an alternating current (a.c.) supply on an oscilloscope.?Each horizontal division on the oscilloscope screen represents a time of 0.01s.(i)??????Calculate the frequency of the a.c. supply..............................................................................................................................................................................................................................................................................................................................................Frequency = ............................................. hertz(2)(ii)?????A diode is now connected in series with the a.c. power supply.?Why does the diode cause the trace on the oscilloscope screen to change?............................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 12 marks)Q9.The diagram shows the structure of a cable. The cable is part of an undersoil heating circuit inside a large greenhouse.?(a) ????The cable is connected to the mains electricity supply through a residual current circuit breaker (RCCB). If the cable is accidentally cut the RCCB automatically switches the circuit off.(i)??????What is the frequency of the mains electricity supply in the UK?...............................................................................................................(1)(ii)?????What happens, as the cable is cut, to cause the RCCB to switch the circuit off?............................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(iii)???? A circuit can also be switched off by the action of a fuse.Give?one?advantage of using a RCCB to switch off a circuit rather than a fuse...............................................................................................................................................................................................................................(1)(b) ????The 230 volt mains electricity supply causes a current of 11 amps to flow through the cable.(i)??????Calculate the amount of charge that flows through the cable when the cable is switched on for 2 hours and give the unit.Use the correct equation from the Physics Equations Sheet..............................................................................................................................................................................................................................................................................................................................................Charge = ..................................................(3)(ii)?????Calculate the energy transferred from the cable to the soil in 2 hours.Use the correct equation from the Physics Equations Sheet...............................................................................................................................................................................................................................Energy transferred =.................................................. J(2)(c) ????The heating circuit includes a thermistor. The thermistor is buried in the soil and acts as a thermostat to control the increase in the temperature of the soil.Describe how an?increase?in the temperature of the soil affects the thermistor.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 11 marks)Q10.(a)???? The diagram shows the circuit used to investigate the resistance of a sample of a material.The diagram is not complete; the ammeter and voltmeter are missing.?(i)??????Draw the symbols for the ammeter and voltmeter on the diagram in the correct places.(2)(ii)?????How can the current through the material be changed?..............................................................................................................................................................................................................................(1)(b) ????The material, called conducting putty, is rolled into cylinders of different lengths but with equal thickness.Graph 1?shows how the resistance changes with length.?Length in centimetres(i)??????The current through a 25 cm length of conducting putty was 0.15 A.Use?Graph 1?to find the resistance of a 25 cm length of conducting putty.Resistance = .................................................. ohms(1)(ii)?????Use your answer to?(b) (i)?and the equation in the box to calculate the potential difference across a 25 cm length of conducting putty.??potential difference = current x resistanceShow clearly how you work out your answer..............................................................................................................................................................................................................................................................................................................................................Potential difference = .................................................. volts(2)(c) ????A second set of data was obtained using thicker pieces of conducting putty. Both sets of results are shown in?Graph 2.?Length in centimetres(i)??????What is the relationship between the resistance and the thickness of the conducting putty?..............................................................................................................................................................................................................................(1)(ii)?????Name?one?error that may have reduced the accuracy of the results................................................................................................................(1)(iii)????How could the reliability of the data have been improved?..............................................................................................................................................................................................................................(1)(Total 9 marks)Q11.(a)????Describe the difference between an alternating current (a.c.) and a direct current (d.c.).................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b) ????The diagram shows how the electric supply cable is connected to an electric kettle.The earth wire is connected to the metal case of the kettle.?If a fault makes the metal case live, the earth wire and the fuse inside the plug protect anyone using the kettle from an electric shock.Explain how.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 4 marks)Q12.????????? (a)???? The resistance of a 24 W, 12 V filament lamp depends on the current flowing through the lamp. For currents up to 0.8 A, the resistance has a constant value of 2.5 Ω.(i)????? Use the equation in the box to calculate the potential difference across the lamp when a current of 0.8 A flows through the lamp.?potential difference????=????current????×????resistanceShow clearly how you work out your answer...............................................................................................................................................................................................................................?????????????Potential difference = ............................................................ V(2)(ii)?????When the potential difference across the lamp is 12 V, the current through the lamp is 2 A.On the axes below, draw a current–potential difference graph for the filament lamp over the range of potential difference from 0 to 12 volts.(2)(iii)????Why does the resistance of the lamp change when the current through the lamp exceeds 0.8 A?..............................................................................................................................................................................................................................(1)(b) ????The lamp is now included in a circuit. The circuit is switched on for 2 minutes. During this time, 72 coulombs of charge pass through the lamp.Use the equation in the box to calculate the energy transformed by the lamp while the circuit is switched on.?energy transformed????=????potential difference????×????chargeShow clearly how you work out your answer.................................................................................................................................................................................................................................................????????????Energy transformed = ............................................................ J(2)(Total 7 marks)??Q13.?????????(a)??? The diagram shows a simple circuit.(i)???? Calculate the total resistance of the two resistors in the circuit................................................................................................................?????????????????????????? Total resistance = .................................................. ?(1)(ii)????? Calculate the reading on the voltmeter.Use the correct equation from the Physics Equations Sheet.Show clearly how you work out your answer...............................................................................................................................................................................................................................??????????????????????? Voltmeter reading = .................................................. V(2)(iii)???? Draw a ring around the correct answer in the box to complete the sentence.??Replacing one of the resistors with a resistor of higher value willdecreasenot changeincrease???the reading on the ammeter.(1)(b)???? The voltmeter in the circuit is replaced with an oscilloscope.Which one of the diagrams,?X,?Y?or?Z, shows the trace that would be seen on the oscilloscope?Write your answer,?X,?Y?or?Z, in the box.?DiagramGive a reason for your answer.........................................................................................................................................................................................................................................................................................................................................................................(2)(Total 6 marks)??Q14.???????? A student used the apparatus below to find out how the resistance of a light-dependent resistor (LDR) depends on light intensity.The resistance of the LDR was measured directly using a multimeter.(a)????(i)?????? Which?one?of the following is the correct circuit symbol for a LDR?Draw a ring around your answer.(1)(ii)???? Name?one?factor that will affect the intensity of the light hitting the LDR...............................................................................................................................................................................................................................(1)(b)???? The manufacturer of the LDR provides data for the LDR in the form of a graph.Describe how the resistance of the LDR changes when the light intensity increases from 100 lux to 300 lux.........................................................................................................................................................................................................................................................................................................................................................................(2)(c)???? The student only obtained three results. These are given in the table.?Light intensityResistance in kilohmsDark750Bright100Very bright1(i)????? The student could?not?use the results to draw a line graph.Why not?..............................................................................................................................................................................................................................(1)(ii)???? Do the student’s results agree with the data the manufacturer provided??Draw a ring around your answer.YESNOGive a reason for your answer..............................................................................................................................................................................................................................................................................................................................................(1)(d)???? Which?one?of the following circuits probably includes a LDR?Tick ()?one?box.?A circuit that automatically switches outside lights on when it gets dark.A circuit that automatically switches central heating on and off.A circuit that automatically turns lights off when no one is in the room.(1)(Total 7 marks)??Q15.???????? The graph shows how the electric current through a 12 V filament bulb varies with the potential difference across the bulb.(a)???? What is the meaning of the following terms?electric current................................................................................................................................................................................................................................................potential difference................................................................................................................................................................................................................................................(2)(b)???? The resistance of the metal filament inside the bulb increases as the potential difference across the bulb increases.Explain why.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c)???? Use data from the graph to calculate the rate at which the filament bulb transfers energy, when the potential difference across the bulb is 6 V.Use the correct equation from the Physics Equations Sheet.Show clearly how you work out your answer.................................................................................................................................................................................................................................................?????????????????????????????????????? Rate of energy transfer = ................................... W(2)(Total 7 marks)??Q16.????????(a)????? The picture shows a person using a set of electronic ‘Body Fat Scales’. When the person stands on the scales, a small, harmless, electric current passes through the person’s body. The scales then calculate the resistance of the person’s body and convert the resistance into a?prediction?of body fat content.(i)????? The scales contain two 3 V cells joined in series.Calculate the resistance of a person’s body, if when he stands on the scales, a current of 0.12 mA passes through his body.1000 mA = 1 AUse the correct equation from the Physics Equations Sheet.Show clearly how you work out your answer and give the unit..............................................................................................................................................................................................................................................................................................................................................?????????????????????????? Resistance = .............................................................(3)(ii)???? The scales can only produce a?prediction?of body fat content and not an accurate measurement.Suggest why..............................................................................................................................................................................................................................................................................................................................................(1)(iii)???? It is recommended that the scales are?not?used immediately after a person has drunk a large amount of water.Suggest why............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)???? The diagram shows how someone could get an electric shock from accidentally cutting into an electric cable. If this happens, and a Residual Current Circuit Breaker (RCCB) is being used, the circuit will switch off automatically.(i)????? A faulty appliance or circuit can be switched off by a RCCB or a pare the action of a RCCB with the action of a fuse............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(ii)???? The graph shows how the severity of an electric shock depends on the size of the current and the time that the current flows through the body.Using the RCCB helps prevent an electric shock seriously injuring the person using the hedge trimmers.Using information from both the diagram and the graph explain how............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 10 marks)??Q17.(a)???? The diagram shows the circuit that a student used to investigate how the current through a resistor depends on the potential difference across the resistor.(i)????? Each cell provides a potential difference of 1.5 volts.What is the total potential difference provided by the four cells in the circuit?...............................................................................................................?????????Total potential difference = .................................................. volts(1)(ii)?????The student uses the component labelled?X?to change the potential difference across the resistor.What is component?X?Draw a ring around your answer.?light-dependent resistorthermistorvariable resistor(1)(iii)????Name a component connected in parallel with the resistor................................................................................................................(1)(b) ????The results obtained by the student have been plotted on a graph.(i)????? One of the results is anomalous.Draw a ring around the anomalous result.(1)(ii)?????Which?one?of the following is the most likely cause of the anomalous result?Put a tick () in the box next to your answer.?The student misread the ammeter.The resistance of the resistor changed.The voltmeter had a zero error.(1)(iii)????What was the interval between the potential difference values obtained by the student?..............................................................................................................................................................................................................................(1)(c) ????Describe the relationship between the potential difference across the resistor and the current through the resistor.................................................................................................................................................................................................................................................(1)(Total 7 marks)??Q18.The diagram shows an electric circuit used in a dolls’ house.The switches are 2-way switches; this means that each switch has a connecting wire that can be in one of two positions.(a)?????(i)????? With the connecting wire in each switch in the position shown in the diagram, the lamp is off. Why?..............................................................................................................................................................................................................................(1)(ii)?????When switched on, the lamp has a resistance of 18 Ω and draws a current of 0.5 A from the power supply.Use the equation in the box to calculate the potential difference of the power supply used in the circuit.?potential difference????=????current????×????resistanceShow clearly how you work out your answer...............................................................................................................................................................................................................................???????????????????????Potential difference = .................................................. V(2)(iii)????A second, identical lamp is added to the circuit. The two lamps are joined in series.Calculate the total resistance of the two lamps................................................................................................................????????????????????????????Total resistance = .................................................. Ω(1)(b) ????This type of circuit is also used in real houses. One of the switches is at the top of the stairs, and the other switch is at the bottom of the stairs.What is the advantage of using this circuit to switch a lamp on or off, rather than using a more simple circuit that has only one switch?................................................................................................................................................................................................................................................(1)(c) ????The diagram shows an old type of metal lamp fitting.The cable has been connected to the lamp fitting in a way that makes the lamp fitting unsafe.(i)????? What is the possible risk to someone touching the lamp fitting while the lamp is switched on?..............................................................................................................................................................................................................................(1)(ii)?????What should be done to make?this?lamp fitting safe to use?..............................................................................................................................................................................................................................(1)(Total 7 marks)??Q19.The diagram shows the circuit set up by a student.(a) ????The student uses the circuit to test the following hypothesis:‘The current through a resistor is directly proportional to the potential difference across the resistor.’(i)????? If the hypothesis is correct, what should the student predict will happen to the current through the resistor when the potential difference across the resistor is doubled?..............................................................................................................................................................................................................................(1)(ii)?????Name the component in the circuit used to change the potential difference across the resistor................................................................................................................(1)(b) ????The student used the data obtained to plot the points for a graph of current against potential difference.(i)????? Why has the student plotted the points for a line graph and not drawn a bar chart?..............................................................................................................................................................................................................................(1)(ii)?????One of the points has been identified by the student as being anomalous.What is the most likely cause for this anomalous point?..............................................................................................................................................................................................................................(1)(iii)????Draw a line of best fit for these points.(1)(iv)?????Does the data the student obtained support the hypothesis?Give a reason for your answer...............................................................................................................................................................................................................................(1)(Total 6 marks)??Q20.The picture shows an electric bicycle. The bicycle is usually powered using a combination of the rider pedalling and an electric motor.(a) ????A 36 volt battery powers the electric motor. The battery is made using individual 1.2 volt cells.(i)????? Explain how a 36 volt battery can be produced using individual 1.2 volt cells.To gain full marks, you must include a calculation in your answer.............................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(ii)?????The battery supplies a direct current (d.c.).What is a?direct current (d.c.)?..............................................................................................................................................................................................................................(1)(iii)????When fully charged, the battery can deliver a current of 5 A for 2 hours. The battery is then fully discharged.Use the equation in the box to calculate the maximum charge that the battery stores.?charge????=????current????×????timeShow clearly how you work out your answer and give the unit...............................................................................................................................................................................................................................???????????????????????Charge stored = ............................................................(3)(b) ????When powered only by the electric motor, the bicycle can carry a 90 kg rider at a maximum speed of 6 m/s. Under these conditions, the maximum distance that the bicycle can cover before the battery needs recharging is 32 km.The bicycle has a mass of 30 kg.(i)????? Use the equation in the box to calculate the maximum kinetic energy of the bicycleand?rider when the rider is not pedalling.?kinetic energy?? =??????×?? mass???×?? speed2Show clearly how you work out your answer...............................................................................................................................................................................................................................?????????????????????Kinetic energy = ............................................................ J(2)(ii)?????The bicycle can be fitted with panniers (bags) to carry a small amount of luggage.What effect would fitting panniers and carrying luggage have on the distance the bicycle can cover before the battery needs recharging?...............................................................................................................Give a reason for your answer...............................................................................................................................................................................................................................(2)(Total 10 marks)??Q21.????????? (a)???? The lamps in the circuits drawn below are all identical.Each of the cells has a potential difference of 1.5 volts.(i)????? What is the potential difference across the 3 cells that are joined in series?...............................................................................................................? ????? ????? ????? ??Potential difference = .................................................. V(1)(ii)?????What will be the reading on the voltmeter labelled?V3????????????????????Voltmeter reading?V3?= .................................................. V(1)(iii)????Which voltmeter,?V1,?V2?or?V3, will give the highest reading?Draw a ring around your answer.?V1V2V3(1)(b) ????The diagram below shows a simple circuit.(i)????? Calculate the total resistance of the two resistors in the circuit................................................................................................................???????????????????????????Total resistance = .................................................. Ω(1)(ii)?????Use the equation in the box to calculate the reading on the voltmeter.?potential difference????=????current????×????resistanceShow clearly how you work out your answer...............................................................................................................................................................................................................................?????????????????????????Voltmeter reading = .................................................. V(2)(iii)????The current through a resistor at constant temperature changes when the potential difference across the resistor changes.Which?one?of the graphs,?X,?Y?or?Z, shows how the current changes?Write your answer,?X,?Y?or?Z, in the box.??????X??????????Y??????????????Z?Graph(1)(Total 7 marks)??Q22.????????? The current–potential difference graph for one type of electrical component is drawn below.(a) ????What is the component?........................................................................................................................(1)(b) ????Complete the diagram to show a circuit that can be used to obtain the data needed to plot the graph. Use the correct circuit symbol for each component that you add to the diagram.(2)(c)?????(i)????? What is the current through the component when the potential difference across the component is 0.8 volts????????????????????????????????????? Current .................................................. amps(1)(ii)?????Use the equation in the box to calculate the resistance of the component when the potential difference across it is 0.8 volts.?potential difference????=????current????×????resistanceShow clearly how you work out your answer...............................................................................................................................................................................................................................???????????????????????????????????Resistance = .................................................. Ω(2)(Total 6 marks)??Q23.????????? A set of lights consists of 20 lamps connected in series to the 230 V mains electricity supply.(a) ????When the lights are switched on and working correctly, the current through each lamp is 0.25 A.(i)????? What is the total current drawn from the mains supply?...............................................................................................................(1)(ii)?????Use the equation in the box to calculate the charge passing through?one?of the lamps in 5 minutes.?charge????=????current????×????timeShow clearly how you work out your answer and give the unit.............................................................................................................................................................................................................................................................................................................................................................................................................................................................???????????????????????????????????? Total charge = ..................................................(3)(b) ????One of the lamps in the set is a fuse lamp. This contains a filament which melts if a fault occurs. A short time after the lights are switched on, a fault causes the filament inside the fuse lamp to melt and all the lamps go out.The householder cannot find another fuse lamp so connects a piece of aluminium foil across the contacts inside the fuse lamp holder.When switched on, the nineteen remaining lamps work.What the householder has done is dangerous.Explain why.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 6 marks)??Q24.Diagram 1?shows a hairdryer.Diagram 2?shows how the heaters and fan of the hairdryer are connected to a 3-pin plug.The hairdryer does not have an earth wire.(a) ????What colour is the insulation around the wire connected to the live pin inside the plug??????????????????????????????????????????????????? ............................................................(1)(b) ????Why does the hairdryer?not?need an earth wire?................................................................................................................................................................................................................................................(1)(c) ????All the switches are shown in the OFF position.(i)????? Which switch or switches have to be ON to make:(1) only the fan work; ............................................................................(2) heater 2 work? ................................................................................(2)(ii)?????The heaters can only be switched on when the fan is also switched on.Explain why............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(d) ????The table shows the current drawn from the 230 volt mains electricity supply when different parts of the hairdryer are switched on.??Current in ampsFan only1.0Fan and heater 14.4Fan and both heaters6.5Use the equation in the box to calculate the maximum power of the hairdryer.?power????=????current????×????potential differenceShow clearly how you work out your answer and give the unit.................................................................................................................................................................................................................................................????????????????????Maximum power = ............................................................(3)(Total 9 marks)??Q25.The diagram shows a strain gauge, which is an electrical device used to monitor a changing force.Applying a force to the gauge causes it to stretch.This makes the electrical resistance of the wire change.?????(a)?????(i)????? Using the correct symbols,?add?to the diagram to show how a battery, an ammeter and a voltmeter can be used to find the resistance of the strain gauge drawn above.(2)(ii)?????When in use, the strain gauge is always connected to a d.c. power supply, such as a battery.How is a d.c. (direct current) power supply different from an a.c. (alternating current) power supply?.............................................................................................................................................................................................................................................................................................................................................(1)(b) ????Before any force is applied, the unstretched gauge, correctly connected to a 3.0 V battery, has a current of 0.040 A flowing through it.(i)????? Use the equation in the box to calculate the resistance of the unstretched gauge.?potential difference????=????current????×????resistanceShow clearly how you work out your answer...............................................................................................................................................................................................................................??????????????????????? Resistance = ............................................................ Ω(2)(ii)?????Stretching the gauge causes the current flowing through the gauge to decrease.What happens to the resistance of the gauge when it is stretched?..............................................................................................................................................................................................................................(1)(iii)????What form of energy is stored in the gauge when a force is applied and the gauge stretches?...............................................................................................................(1)(Total 7 marks)??Q26.????????? A circuit diagram is shown below.(a) ????Use a word from the box to label component?X.?fuseswitchthermistor(1)(b) ????Calculate the total resistance of the two resistors in the circuit.........................................................................................................................??????????????????????????????????????Total resistance = ........................................ Ω(1)(c) ????The reading on the ammeter is 0.25 A.The current through the 6 Ω resistor will be:?bigger than 0.25 Aequal to 0.25 Asmaller than 0.25 ADraw a ring around your answer(1)(d) ????The 6 V battery is made by correctly joining several 1.5 V cells in series.Calculate the number of cells needed to make the battery.........................................................................................................................??????????????????????????????????????Number of cells = ...........................................(1)(Total 4 marks)??Q27.????????? The diagram shows a simple circuit.(a) ????The circuit includes an LDR.What do the letters LDR stand for?Draw a ring around your answer.?Light-dependable resistorlight-dependent resistorlight-direct resistor(1)(b) ????The graph shows how the resistance of an LDR changes with light intensity.Describe in detail how the resistance of the LDR changes as the light intensity increases from 0 to 50 lux.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c)?????(i)?????Complete the following sentence by drawing a ring around the correct line in the box.??decrease?A decrease in the light intensity of light on the LDR willnot changethereading on the ammeter.increase?(1)(ii)?????Give a reason for your answer to part (c)(i)...............................................................................................................................................................................................................................(1)(d) ????An LDR can be used to switch a circuit on and off automatically.In which?one?of the following would an LDR be used?Put a tick () in the box next to your answer.?a circuit to switch on central heating when it gets colda circuit to switch on security lighting when it gets darka circuit to switch on a water sprinkler when the soil in a greenhouse is dry(1)(Total 7 marks)??Q28.????????? The diagram shows a simple light-sensing circuit.(a) ????The graph, supplied by the manufacturer, shows how the resistance of the component labelled?X?varies with light intensity.(i)????? What is component?X?...............................................................................................................(1)(ii)?????Use the graph to find the resistance of component?X?when the light intensity is 20 lux................................................................................................................(1)(iii)????When the light intensity is 20 lux, the current through the circuit is 0.0002 A.Use the equation in the box to calculate the reading on the voltmeter when the light intensity is 20 lux.?potential difference???=???current???×???resistanceShow clearly how you work out your answer...............................................................................................................................................................................................................................??????????????????????Voltmeter reading =.................................................. volts(2)(b) ????Use the grid below to show how the voltmeter reading in the light-sensing circuit varies with light intensity.(i)????? Add a suitable scale to the?y-axis (vertical axis).(1)(ii)?????Complete the sketch graph by drawing a line on the grid to show how the voltmeter reading will vary with light intensity.(2)(c) ????The following passage is taken from the technical data supplied for component?X?by the manufacturer.?For any given light intensity, the resistance of this component can vary by plus orminus 50% of the value shown on the?graph of light intensity and resistance.(i)????? Calculate the maximum resistance that component?X?could have at 20 lux light intensity................................................................................................................???????????Maximum resistance =.................................................. kilohms(1)(ii)?????Explain why this light-sensing circuit would?not?be used to measure values of light intensity..............................................................................................................................................................................................................................................................................................................................................(2)(Total 10 marks)??Q29.????????? (a)????The diagram shows a student touching the metal dome of a Van de Graaff generator.When the generator is switched on, the metal dome becomes negatively charged.Explain why the student’s hair stands on end when the generator is switched on.........................................................................................................................................................................................................................................................................................................................................................................(2)(b) ????When the potential difference between the student and a nearby earthed metal dome reached 15 kV, a spark jumped between the student and the earthed dome. The spark transformed 30 mJ of energy into heat, light and sound. (1 mJ = 0.001 J)Use the equation in the box to calculate the charge carried by the spark.?energy transformed???=???potential difference???×???charge................................................................................................................................................................................................................................................???????????Charge transferred =.................................................. coulombs(2)(c) ????What name is given to the rate of flow of charge?........................................................................................................................(1)(Total 5 marks)??Q30.????????? A student used a joulemeter to measure the energy transformed by a lamp.The student set the joulemeter to zero, and then switched on the power supply.After 120 seconds (2 minutes), the reading on the joulemeter had increased to 2880.(a) ????In the space below, draw the circuit symbol used to represent a lamp.??(1)(b)?????(i)????? Use the equation in the box to calculate the power of the lamp.Show clearly how you work out your answer...............................................................................................................................................................................................................................??????????????????????????????????????????????Power = ..................................................(2)(ii)?????Which?one?of the following is the unit of power?Draw a ring around your answer.?joulenewtonwatt(1)(c) ????Complete the following sentence using one of the phrases from the box.?larger thanthe same assmaller thanIf the lamp was left switched on for 10 minutes, the amount of energy transformed wouldbe ........................................................................... the amount of energy transformed in2 minutes.(1)(Total 5 marks)??plete each of the following sentences,?A,?B,?C,?D?and?E, by choosing the correct ending from?K,?L,?M,?N?or?O.The first one has been done for you.?AThe current through a resistor depends ............................................................BA direct current .................................................................................................CIn a series circuit, the potential difference ........................................................DAn alternating current .......................................................................................EIn a parallel circuit, the potential difference ......................................................K????.......................................................................... across each component is the same.L???? .................................................................................... is supplied by a cell or battery.M????................................................................................. is constantly changing direction.N???? ..................................................... of the power supply is shared by the components.O????............................................................ on the potential difference across the resistor.(Total 3 marks)??Q32.????????? (a)???? The graphs show how the velocity of two cars,?A?and?B, change from the moment the car drivers see an obstacle blocking the road.Car A ????????????????????????????????????????????????????????Car B?One of the car drivers has been drinking alcohol. The other driver is wide awake and alert.(i)????? How does a comparison of the two graphs suggest that the driver of car?B?is the one who has been drinking alcohol?..............................................................................................................................................................................................................................(1)(ii)?????How do the graphs show that the two cars have the same deceleration?..............................................................................................................................................................................................................................(1)(iii)????Use the graphs to calculate how much further car?B?travels before stopping compared to car?A.Show clearly how you work out your answer..............................................................................................................................................................................................................................................................................................................................................???????????Additional stopping distance = ............................................... m(3)(b) ????In a crash test laboratory, scientists use sensors to measure the forces exerted in collisions. The graphs show how the electrical resistance of 3 experimental types of sensor,?X,?Y?and?Z, change with the force applied to the sensor.Which of the sensors,?X,?Y?or?Z, would be the best one to use as a force sensor?????????????????????????????????????????????????????????????..................................................Give a reason for your answer.................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 7 marks)??Q33.????????? Use words from the box to label the components,?A,?B, and?C, in the circuit diagram.?cell????????? diode????????? lamp?????????? resistor???????? switch??????????(Total 3 marks)??Q34.????????? A student used the apparatus below to find out how the resistance of a thermistor changes with temperature.The student heated the water slowly using a Bunsen burner.The resistance of the thermistor was measured using an ohmmeter.(a)???? (i)????? Before doing the experiment the student completed a risk assessment.Which?one?of the following is a hazard in this experiment?Tick ()?one?box.?Using an ohmmeter near waterBoiling water in a beakerHanging the thermistor in water(1)(ii)???? The student measured the water temperature using a temperature probe and data logger rather than a glass thermometer.??????????Give?two?reasons for using a temperature probe and data logger rather than a glass thermometer to measure temperature.............................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)???? The data obtained by the student is displayed in the graph.What conclusions should the student make from the data displayed in the graph?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c)???? In which?one?of the following circuits is there likely to be a thermistor?Tick ()?one?box.?One that automatically switches lights on when it gets darkOne that automatically monitors the moisture level in soilOne that acts as a thermostat to switch heating on and off(1)(Total 7 marks)??Q35.????????? A student used the apparatus below to find out how the resistance of a thermistor changes with temperature.The student heated the water slowly using a Bunsen burner.The resistance of the thermistor was measured using an ohmmeter.(a)???? (i)????? Before doing the experiment the student completed a risk assessment.Which?one?of the following is a hazard in this experiment?Tick ()?one?box.?Using an ohmmeter near waterBoiling water in a beakerHanging the thermistor in water(1)(ii)???? The student measured the water temperature using a temperature probe and data logger rather than a glass thermometer.??????????Give?two?reasons for using a temperature probe and data logger rather than a glass thermometer to measure temperature.............................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)???? The data obtained by the student is displayed in the graph.What conclusions should the student make from the data displayed in the graph?................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c)???? In which?one?of the following circuits is there likely to be a thermistor?Tick ()?one?box.?One that automatically switches lights on when it gets darkOne that automatically monitors the moisture level in soilOne that acts as a thermostat to switch heating on and off(1)(Total 7 marks)???M1.(a)???? (i)??????any?six?from:?????????switch on?????????read both ammeter and voltmeterallow read the meters?????????adjust variable resistor to change the current?????????take further readings?????????draw graph?????????(of) V against Iallow take mean?????????R = V / Iallow take the gradient of the graph6(ii)?????resistor would get hot if current left on1so its resistance would increase1(iii)????12 (V)0.75 × 16 gains?1?mark2(iv)????15 (?)116 is nearer to that value than any other1(b)???? if current is above 5 A / value of fuse1fuse meltsallow blows / breaksdo?not?accept exploded1breaks circuit1[15]M2.(a)???? decreases1(b) ????a filament bulballow bulb1an LED1(c) ????Marks awarded for this answer will be determined by the Quality of Communication (QoC) as well as the standard of the scientific response.0 marksNo relevant content.Level 1 (1?2 marks)There is a basic description of the method. This is incomplete and would not lead to any useful results.Level 2 (3?4 marks)There is a description of the method which is almost complete with a few minor omissions and would lead to some results.Level 3 (5?6 marks)There is a detailed description of the method which would lead to valid results.To gain full marks an answer including graph, or another appropriate representation of results, must be given.examples of the physics points made in the response:?????????read V and I?????????read temperature?????????apply heatallow hot water to cool?????????read V and I at least one other temperature?????????determine R from V / I?????????range of temperatures above 50 °Cextra detail:?????????use thermometer to read temperature at regular intervals of temperature?????????remove source of heat and stir before taking readings?????????details of attaining 0 °C or 100 °C?????????last reading taken while boiling?????????graph of R against T?????????at least 3 different temperatures6(d)???? (i)??????Q1(ii)?????(80, 3.18)1(iii)????any?one?from:?????????measurement of V too small?????????measurement of I too big?????????incorrect calculation of R?????????thermometer misreadallow misread meterignore any references to an error that is systematic1(iv)????any?two?from:?????????not portableallow requires a lot of equipment allow takes time to set up?????????needs an electrical supply?????????cannot be read directlyaccept it is more difficult to read compared to liquid-in-glass2[14]M3.(a)???? (i)??????neutral1(ii)?????brown1(b)???? (i)??????centre symbol ringed?accept any correct indication1(ii)?????fuse (wire) meltsaccept fuse blowsaccept fuse breaks / snapsaccept burns out appliance doesn’t work is insufficientoverheat is insufficientdo?not?accept blows up1(c)???? (i)??????Toaster1(only one with) a metal case / outsidereason only scores if toaster chosenaccept it is metal?accept outside / case / metal conducts (electricity)do?not?accept it conducts electricity1(ii)?????electric shock / electrocutiondo?not?accept explosion1(d) ????overheating of cables?or?fireit refers to the electric cableaccept short circuit / sparkingoverheating of tape is insufficientdo not accept electrocution / shock1(e) ????stop cable(s) being pulled loose / freeaccept wire(s) for cable(s)?accept to hold cables in place1and so breaking the circuit?or?and shorting (one wire to another)or?and causing a fire risk / sparkingaccept appliance / plug would not work1[10]M4.(a)????(i)?????? to obtain a range of p.d. valuesaccept increase / decrease current / p.d. / voltage / resistanceaccept to change / control the current / p.d. / voltage / resistanceto provide resistance is insufficienta variable resistor is insufficientdo?not?accept electricity for current1(ii)?????temperature of the bulb increasesaccept bulb gets hot(ter)accept answers correctlyexpressed in terms of collisions between (free) electrons and ions / atomsbulb gets brighter is insufficient1(iii)????36allow?1?mark for correct substitution, ie 12 × 3 provided no subsequent step shown2watt(s) / Waccept joules per second / J/sdo?not?accept w1(b) ????Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. Examiners should also refer to the information in the?Marking guidance, and apply a ‘best-fit’ approach to the marking.0 marksNo relevant content.Level 1 (1-2 marks)There is a basic comparison of either a cost aspect or an energy efficiency aspect.Level 2 (3-4 marks)There is a clear comparison of either the cost aspect or energy efficiency aspectORa basic comparison of both cost and energy efficiency aspects.Level 3 (5-6 marks)There is a detailed comparison of both the cost aspect and the energy efficiency aspect.For full marks the comparisons made should support a conclusion as to which type of bulb is preferable.Examples of the points made in the response:cost????????? halogen are cheaper to buysimply giving cost figures is insufficient????????? 6 halogen lamps cost the same as one LED????????? LEDs last longer????????? need to buy 18 / more halogen lamps to last the same time as one LED????????? 18 halogens cost ?35.10????????? costs more to run a halogen than LED????????? LED has lower maintenance cost (where many used, eg large departmental store lighting)energy efficiency????????? LED works using a smaller current????????? LED wastes less energy????????? LEDs are more efficient????????? LED is 22% more energy efficient????????? LED produces less heat????????? LED requires smaller input (power) for same output (power)6[11]M5.(a)???? 35an answer with more than 2 sig figs that rounds to 35 gains?2marksallow?2?marks for correct method, ie ?allow?1?mark for I = 6.5 (A)?or?R = ?an answer 8.8 gains?2?marksan answer with more than 2 sig figs that rounds to 8.8 gains?1mark3(b)???? (i)??????(maximum) current exceeds maximum safe current for a 2.5 mm2?wireaccept power exceeds maximum safe power for a 2.5 mm2?wireor(maximum) current exceeds 20 (A)(maximum) current = 26 (A) is insufficient1a 2.5 mm2?wire would overheat / meltaccept socket for wiredo?not?accept plug for wire1(ii)?????(contains) live, neutral and earth wiresaccept is a three-core cable1cross-sectional area of (live and neutral) wire(s) (minimum of) 4 mm2accept 6 mm2?for 4 mm21wire / cable should be insulatedaccept a suitable named insulator, eg PVC / rubber / plastic1(c) ???? a.c. is constantly changing directionaccept a.c. flows in two directionsaccept a.c. changes directiona.c. travels in different directions is insufficient1d.c. flows in one direction only1[10]M6.(a)???? 25(Ω)1(b)???? (i)??????2(V)allow?1?mark for showing a correct method, ie 6 / 32(ii)?????equal to1[4]M7.(a)???? (i)?????? 50 (Hz)1(ii)????? 2760 (W)1(b) ???? 12allow?1?mark for correct substitution, ie 2400/200orallow?1?mark for 2760/230 provided no subsequent step shown2amps1(c) ????the charge is?directly?proportional to the time switched on foraccept for?1?mark the longer time (to boil), the greater amount of chargeor?positive correlationor?they are proportional2[7]M8.(a)???? (i)??????symbol for a diode ?accept??1symbol for a variable resistor??1(ii)????? voltmeter is in series?or?voltmeter is not in parallel1ammeter is in parallel?or?ammeter is not in seriesaccept an answer in terms of how the circuit should be correctedvoltmeter and ammeter are wrong way around is insufficient1(b)???? (i)??????0.2 (V)accept any value between 0.20 and 0.21 inclusive1(ii)?????37.5allow?1?mark for I = 0.008?or?allow?2?marks for correct substitution, ie 0.3 = 0.008 × R?or?allow?1?mark for a correct substitution using I = 0.8?or?I = 0.08or?I = 0.009?or?allow?2?marks for answers of 0.375?or?3.75?or?33(.3)3(c)???? (i)?????? 25allow?1?mark for obtaining period = 0.04(s)2(ii)?????diode has large resistance in reverse / one direction1so stops current flow in that / one directionallow diodes only let current flow one way / directionallow?1?mark for the diode has half-rectified the (a.c. power) supply1[12]M9.(a)???? (i)?????? 50(Hz)ignore any unit given1(ii)????? any?two?from:?????????(some) current flows to Earthaccept ground for Earth?????????current flows through copper braidaccept current flows through the earth wireaccept electricity for current in either the first or second marking point but not both?????????RCCB detects difference between?current?in live and neutral wire2(iii)????can be resetaccept does not need replacingorfaster actingaccept switches circuit off faster1(b)???? (i)?????? 79 200allow?1?mark for correct substitution, ie 11 = ?an answer 22 gains?1?mark2coulombs / Cdo?not?accept c1(ii)????? 18 216 000accept for?2?marks 18 216 kJ?or?18.216 MJor230 × their (b)(i) correctly calculatedallow?1?mark for correct substitution, ie 230 × their (b)(i)?or?allow?1?mark for power calculated as 2530(W)2(c) ???? increases temperature of thermistor1changes resistance (of thermistor)do?not?accept increases resistance (of thermistor)an answer decreases resistance (of thermistor) gains?2?marks1[11]M10.(a)???? (i)??????ammeter symbol correct and drawn in seriesaccept ?do?not?accept lower case a1voltmeter symbol correct and drawn in parallel with the materialdo?not?accept ?1(ii)????? adjust / use the variable resistoraccept change the resistanceorchange the number of cellsaccept battery for cell?accept change the pd / accept change the voltageaccept increase / decrease for change1(b)???? (i)??????37.5 (Ω)accept answer between 36 and 39 inclusive1(ii)????? 5.6(25)?or?their (b)(i) × 0.15allow?1?mark for correct substitution ie 37.5?or?their (b)(i) × 0.15 provided no subsequent step shown2(c)???? (i)??????the thicker?the putty the lower?the resistanceanswer must be comparativeaccept the converse1(ii)?????any?one?from:????????? measuring length incorrectlyaccept may be different length????????? measuring current incorrectlydo?not?accept different currents????????? measuring voltage incorrectlydo?not?accept different voltage????????? ammeter / voltmeter incorrectly calibrated????????? thickness of putty not uniformdo?not?accept pieces of putty not the same unless qualified????????? meter has a zero errordo?not?accept systematic / random erroraccept any sensible source of error eg putty at different temperatures?do?not?accept human error without an explanation?do?not?accept amount of putty not same1(iii)????repeat readings and take a meanaccept check results againaccept do experiment againaccept do it again and take mean(s)?accept compare own results with other groupsdo?not?accept take more readings1[9]M11.(a)????d.c. flows in (only) one direction1a.c.?changes?direction (twice every cycle)accept a.c. constantly changing directionignore references to frequency1(b) ????a current flows through from the live wire / metal case to the earth wireaccept a current flows from live to earthdo?not?accept on its own if the current is too high1this current causes the fuse to meltaccept blow for meltdo?not?accept break / snap / blow up for melt1[4]M12.?????????(a)????? (i)?????2allow?1?mark for correct substitution i.e. 0.8 × 2.5 provided no further step shown2(ii)?????straight line drawn from origin to 2, 0.8ortheir (a)(i), 0.81curve from 2, 0.8 to 12,2ortheir (a)(i) 0.8 to 12,2accept curve from 2, 0.9 to 12,2ortheir (a)(i) 0.9 to 12,2‘convex’ curve requiredaccept a curve that flattens between 10 and 12V1(iii)????filament / lamp gets hotaccept temperature increases1(b) ????108allow?1?mark for correct substitution i.e. 1.5 × 72 provided no further step shown2[7]?M13.?????????(a)??????(i)???? 151(ii)???? 4.5 or their (a)(i) x 0.3 correctly calculatedallow?1?mark for correct substitution, ie 0.3 x 15/their (a)(i), provided no subsequent step2(ii)???? decrease1(b)?????Yaccept any correct indicationreason only scores if?Y?is chosenaccept voltage for p.d.1(only one that) shows a direct current / p.d.ora battery / cell gives a direct currentaccept both?X?and?Z?are a.c.ora battery/cell gives a constant current/p.d.accept it’s a constant current/p.d.it is not changing is insufficient1[6]?M14.?????????(a)???????(i)???? correct symbol ringed1(ii)???? accept any suggestion that would change light intensity, eg:???????? torch on or offaccept power of torchdo?not?accept watts / wattage of torch???????? distance between torch and LDR???????? lights in room on or off???????? shadow over the LDR1(b)???? resistance decreases1from 600 k? to 200 k?accept by 400 k?1(c)?????(i)????? no numbers for light intensityorlight intensity is categoric / a description / not continuousnot enough results is insufficient1(ii)???? YESmark is for the reasonboth show that resistance increases with decreasing (light)intensity / brightnessaccept they both get the same results / pattern1(d)???? A circuit that automatically switches outside lights on when it gets dark.1[7]?M15.?????????(a)???? electric current(rate of) flow of (electric) charge / electronsaccept?with Q and t correctly named1potential differencework done / energy transferred per coulomb of charge?(that passes between two points in a circuit)accept?with W and Q correctly named1(b)???? metals contain free electrons (and ions)accept mobile for free1as temperature of filament increases ions vibrate faster /?with a bigger amplitudeaccept atoms for ionsaccept ions/atoms gain energyaccept vibrate more for vibrate fasterdo not accept start to vibrate1electrons collide more (frequently) with the ionsor(drift) velocity of electrons decreasesdo not accept start to collideaccept increasing the p.d. increases the temperature (1?mark)and(and) resistance increases with temperature (1?mark) if no other marks scored1(c)???? 7.8allow?1?mark for obtaining value 1.3 from graphor?allow?1?mark for a correct calculation using an incorrect current in the range 1.2-1.6 inclusive2[7]?M16.?????????(a)???????(i)???? 50 000allow?1?mark for correct substitution, ie6 = 0.00012 × Ror?6 = 0.12 × Ror?answers of 25 000 or 50 gain?1?markor?allow 1 mark for an incorrect answer caused by one error only ie using 3V or an incorrect conversion of current2ohm / ?an answer 50k? gains?3?marks1(ii)???? (body) resistance changesorbody fat/resistance affected by (many) factorsaccept named factor, eg age, gender, height, fitness, bone structure, muscle, drinking water related to body fat / resistance1(iii)???? gives misleading / wrong/inaccurate valuedo not credit if specifically linked to a change in mass / weight1(because) high water content changes body resistanceaccept a specific change to resistancewater changes body mass is insufficient1(b)????(i)?????? RCCB – detects difference between current in live and neutral (wires)accept RCCB can be reset1fuse – (overheats and) meltsaccept blows for melts1(ii)???? switches the circuit / hedge trimmers off within 60 millisecondsallow for?1?mark the RCCB / it is (very) fast.do not accept the bigger the current the faster the RCCB?switches off2[10]?M17.?????????(a)????? (i)?????61(ii)?????variable resistor1(iii)????voltmeter1(b)?????(i)????? point at 3 V ringed1(ii)?????The student misread the ammeter.1(iii)????1 (volt)accept every volt1(c) ????as one increases so does the otherordirectly proportionalorpositive correlationaccept a numerical description, eg when one doubles the other also doubles1[7]?M18.?????????(a)????? (i)?????circuit not completeaccept circuit is brokenaccept switch / s are open / off1(ii)?????9allow?1?mark for correct substitution, ie 0.5 × 18 provided no subsequent step shown2(iii)????361(b) ????can be switched on / off from top or bottom of stairs1(c)?????(i)????? (electric) shockaccept fitting becomes liveaccept answers giving a possible consequence of electric shock, eg death1(ii)?????connect the?earth?wire1[7]?M19.?????????(a)????? (i)?????also doubleincreases is insufficient1(ii)?????variable?resistoraccept rheostat / potentiometer1(b)?????(i)????? the data / results / variables are continuousaccept data / results / variables are not categoric / discrete1(ii)?????misreading the ammeterdo?not?accept misreading the meter / resultsdo?not?accept misreading the ammeter and / or voltmeterreading / human error is insufficient1(iii)????straight line?from the origin?drawn passing close / throughpoints at 1 V, 5 V, 6 V and ignoring anomalous pointdo?not?accept line drawn ‘dot-to-dot’1(iv)?????yesmark is for the reasonsupports predictionor(straight) line passes through the originaccept a mathematical argument, eg when p.d. went from 2 to 4 the current went from 0.3 to 0.6it’s directly proportional is insufficient1[6]?M20.?????????(a)????? (i)?????(connect) 30 (cells)1in series1(ii)?????current always flows in the same directionorcurrent only flows one way1(iii)????36 000allow?1?mark for correctly converting 2 hours to 7200 secondsanswers 10 or 600 score?1?mark2coulombs / Cdo?not?accept c1(b)?????(i)????? 2160allow?1?mark for correct substitution, ie ? × 120 × 62answers of 1620 or 540 score?1?mark2(ii)?????reduce it1any?one?from:?????????draws a larger current (from battery)?????????motor draws greater power (from battery)accept energy per second for poweraccept more energy needed to move the bicycle?????????greater resistance force (to motion) / air resistance / drag / frictionaccept less streamlinedmore mass to carry is insufficient1[10]?M21.?????????(a)????? (i)?????4.51(ii)?????2.25 or their (a)(i) ÷ 2 correctly calculated1(iii)????V21(b)?????(i)????? 301(ii)?????8allow?1?mark for correct substitutionie 0.4 × 20allow?1?mark for answers of 4 or 122(iii)????Y1[7]?M22.????????? (a)???? diodeaccept LED1(b) ????all symbols correctmust include at least voltmeter and diode1??????diodeallow ecf from part (a) if the component is not identified as a diodeallow symbol without the line through triangleignore polarity of diodevoltmeter in parallel with component added in seriesany additional components must not affect the ability to measure?Vand?I?for the diode / their (a)1(c)?????(i)????? 0.05accept 50 mAaccept between 0.048 and 0.050 inclusive1(ii)?????16?????0.8??????their (c)(i) correctly calculated gains both marksallow?1?mark for correct transformation and substitutionallow 17 if using 0.0482[6]?M23.?????????(a)????? (i)?????0.25 (A)1(ii)?????75allow?1?mark for converting 5 minutes to 300 secondsor?allow?1?mark for correct substitutionie 0.25 × 300allow?1?mark for an answer 1.25allow?1?mark only for their (a)(i) × 300 correctly calculated2coulombs or Cdo?not?accept c1(b) ????any?two?from:?????????fault not repairedaccept if a fault was to occur?????????larger current will (still) flow?????????aluminium foil will not melt (if a fault)accept aluminium foil needs a higher current / charge to melt?????????wiring will overheat / (may) cause a fireaccept idea of fire hazarddo?not?accept explode etc2[6]?M24.????????? (a)???? brown1(b) ????outside / case is plastic / an insulatoraccept is double insulatedaccept non-conductor for plasticdo?not?accept it / hairdryer is plastic1(c)?????(i)????? (1) S1and no other1(2) S1?and S3both required, either order1(ii)?????S1?must be ON (for either heater to work)do?not?accept reference to ‘fan’ switch1S1?switches the fan on1(d) ????1495allow?1?mark for correct substitutionie, 6.5 × 2302watt(s) or Wan answer of 1.495 kW gains?3?marksalthough the unit is an independent mark for full creditthe unit and numerical value must be consistentaccept joules per second or J/s1[9]?M25.?????????(a)????? (i)?????ammeter and battery?in series?with the?gaugesymbols must be correctignore a voltmeter drawn in seriesor cells reversed to cancel out1voltmeter in parallel with the gaugesymbol must be correctaccept a freestanding circuitdiagram provided strain gauge is labelled or a resistor symbol used for the strain gauge1(ii)?????d.c. flows only in one directiona.c. changes direction is insufficient1(b)?????(i)????? 75this answer onlyallow?1?mark for correct substitution?and?transformation,ie resistance =?2(ii)?????increases1(iii)????elastic / strain?potentialdo?not?accept potential1[7]?M26.????????? (a)???? switchallow answer circled in box1(b) ????241(c) ????equal to 0.25 A1(d) ????41[4]?M27.????????? (a)???? a light-dependent resistor1(b) ????any?three?from:?????????resistance starts at 500 (kilohms)?????????(resistance) falls rapidly as intensity increases from 0accept resistance fallsaccept brightness for intensity?????????(resistance) halves between 10 and 20 lux?????????(resistance) falls slightly between 20 and 50 luxor?????????(resistance) almost constant / levels out between 20 and 50 lux?????????at 50 lux, resistance = 10 (kilohms)for full credit the word resistance must be used correctly at least oncean answer resistance falls as intensity increases gains?2?marks - this may be combined with one of the bullet point marks for full credit3(c)?????(i)?????decrease1(ii)?????resistance increasesthis can score without (c)(i)1(d) ????A circuit to switch on security lighting when it gets dark.1[7]?M28.?????????(a)????? (i)?????light dependent resistor / LDRaccept ldr1(ii)?????25 (kilohms)accept 24 - 26 inclusiveaccept 25 000 Ω1(iii)????5 (V) or their (a)(ii) correctly converted to ohms × 0.0002 correctly calculatedallow?1?mark for converting 25 kΩ /their (a)(ii) to ohmsorallow?1?mark for correct substitutionie 0.0002 × 25(000)or?0.0002 × their (a)(ii)allow an incorrect conversion from kilohms providing this is clearly shown2(b)?????(i)?????linear scaleusing all of the available axismust cover the range 4 - 6 vor?their (a)(iii) - 6 v and lie within the range 0 - 15 inc.1(ii)?????negative gradient linedo?not?allow lines with both positive and negative gradients1passing through 20 lux and their (a)(iii)only scores if the first mark is awardedonly scores if line does not go above 6 volts1(c)?????(i)?????37.5 (kΩ) or their (a)(ii) + 50 % (a)(ii) correctly calculated1(ii)?????light intensity value would be unreliable / not accurate1due to variation in?resistance?valueaccept because resistance varies by ± 50 %accept tolerance of resistor is too greatdo?not?accept results are not accurate1[10]?M29.????????? (a)???? each hair gains the?same?(type of) chargeor(each) hair is negatively chargeddo?not?accept hair becomes positively chargedor(each) hair gains electrons1similar charges repelaccept positive charges repelproviding first marking point is in terms of positive chargeornegative charges repelorelectrons repel1(b) ????0.000002accept correct substitution and transformation for?1?markor?2 × 10-6ie 30 / 15 or .03 / 15000 or 30 / 15000 or .03 / 15or?2 μ Canswers 2 and 0.002 gain?1?mark2(c) ????currentdo?not?accept amp / amperes1[5]?M30.????????? (a)????accept ‘the humpback bridge’ symbolaccept circle with cross but no linesif more than one symbol drawn, no mark unless lamp is labelled1(b)?????(i)????? 24allow?1?mark for correct substitution ie?allow?1?mark for an answer 1440ignore any unit2(ii)?????watt1(c) ????larger thanaccept correct indication inside the boxaccept an answer meaning larger than ie greater than1[5]?M31.LNMKall four in the correct order2?marks for 2 correct1?mark for 1 correct[3]?M32.?????????(a)????? (i)?????longer reaction timeaccept slower reactionsdo?not?accept slower reaction time unless qualifiedorgreater thinking distanceaccept greater thinking timeorgreater stopping distanceaccept greater stopping timegreater braking distance negates answer1(ii)?????lines / slopes have the same gradientaccept slopes are the sameorvelocity decreases to zero in same time / in 2.6 secondsaccept any time between 2.3 and 2.8accept braking distances are the same1(iii)????12accept extracting both reaction times correctly for?1?mark(0.6 and 1.4 )?or?time = 0.8(s) for?1?markaccept 0.8 × 15 for?2?marksaccept calculating the distancetravelled by car?A?as 28.5 m?or?the distance travelled by car?B?as 40.5 m for?2?marks3(b) ????Z1different force values give a unique / different resistanceonly scores if?Z?chosendo?not?accept force andresistance are (directly) proportionalaccept answers in terms of whyeither?X?or?Y?would not be the best egX?– same resistance value is obtained for 2 different force valuesY?– all force values give the same resistance1[7]?M33.??????????A?– switch1B?– cell1C?– diode1[3]??M34.?????????(a)???? (i)????? boiling water in a beaker1(ii)???? any?two?from:???????? more precise???????? sensitive???????? accurate2(b)???? higher the temperature, lower the resistance1plus additional detaileg resistance falls fastest between 0-20°Cmaximum of?2?marks, 1 for each additional correct detailresistance falls slowest between 80-100°Caccept for?1?markresistance is not constant (at all temperatures)3(c)???? one that acts as a thermostat to switch heating on and off1[7]??M35.?????????(a)???? (i)????? boiling water in a beaker1(ii)???? any?two?from:???????? more precise???????? sensitive???????? accurate2(b)???? higher the temperature, lower the resistance1plus additional detaileg resistance falls fastest between 0-20°Cmaximum of?2?marks, 1 for each additional correct detailresistance falls slowest between 80-100°Caccept for?1?markresistance is not constant (at all temperatures)3(c)???? one that acts as a thermostat to switch heating on and off1[7]???E2.(a)???? Nearly all students knew that when the resistance of a circuit increases the current in it decreases.(b)???? Nearly three-quarters of the students recognised the description of a filament bulb and a LED.(c)???? The Quality of Communication question was a description of an experiment where the change in resistance of metal with temperature was investigated.Many students wasted time, and used a substantial fraction of the answer lines, describing the electrical circuit provided. Just under half of the students scored four marks out of six for an adequate account that could be repeated to give sufficient data.Students who scored more than four marks often included a graph of resistance against temperature or some detail such as removing the Bunsen burner and stirring the water before taking readings.Those who scored three marks or less often did not state how resistance could be calculated from the meter readings, or did not state that the meters had to be read at all but that ‘resistance had to be recorded’ at each temperature.(d)???? (i)??????Almost all students could relate a range of resistance values in a table to those represented on a graph.(ii)?????Almost all students were able to circle an anomalous value on the graph.(iii)????Surprisingly, less than half the students were able to suggest a reason for the anomalous results such as misreading the thermometer or meters or incorrectly calculating resistance.(iv)????About a third of students were able to suggest a disadvantage of a resistance thermometer compared to a liquid-in-glass thermometer. About one tenth could suggest two, including the need for an electrical supply and that temperature could not be read directly.E3.(a)???? (i)??????Half of the students scored this mark.(ii)?????This was better known with a majority of students giving the correct answer.(b)???? (i)??????A majority of students were able to identify the circuit symbol for a fuse.(ii)????? A majority of students answered this question correctly, with most of the incorrect responses being in terms of the fuse blowing up or exploding, or statements regarding the shattering of the glass or metal caps.(c)???? (i)??????Although most students correctly identified the toaster as the appliance needing an earth wire, the second mark was harder to achieve as a significant number of students thought that the metal casing was present due to heat considerations.(ii)????? Most students answered correctly that an electric shock or electrocution would be the possible risk from the appliance, the most common incorrect response involved overheating and subsequent burns to a person.(d) ????Few students were aware that the inappropriate connection of the wires would cause sparking and heating of the wires. There were many vague responses solely in terms of the overheating of the tapes or the possibility of electrocution.(e) ????A majority of the students explained how the use of a connecting box could be a secure way to join two lengths of electrical cable but there were very few correct answers that gained both marks by continuing the answer to explain why this was important.E4.(a)???? (i)??????This was very poorly answered with few students realising what the function of ‘J’ was in the circuit. A significant number of students did identify ‘J’ as a variable resistor but did not go on to say what it does.(ii)?????Again very poorly answered with only a very small minority of students understanding that the resistance increases as the temperature of the bulb increases.(iii)???? Again the calculation was well done with nearly three quarters of students giving the correct numerical answer. However the unit was not well known with only just over one fifth of students giving the correct one.(b) ????Most students managed to score some marks on this question with the majority of students at level 2 and gaining 3 or 4 marks. Comparison of the cost aspect was done best by students, with many correctly calculating the need for 18 halogen bulbs to last as long as 1 LED and the higher associated costs. Very few students made a comment on efficiency beyond the fact that LEDs were more efficient. A lot could have been written about energy efficiency such as less waste energy, less heat produced, lower power input and lower running costs for the LED bulb. Even a simple statement of not having to change the LED bulb as often as the halogen bulb was not common. There were a small number of students who believed that you could increase the efficiency by adding more bulbs. So for example if you had 4 halogen bulbs at 10% efficiency then this would give you 40% efficiency. This led to erroneous conclusions that you could make halogen bulbs more efficient than an LED bulb. There were also a small number of students who believed that the higher the number for efficiency the more energy was wasted and so a higher efficiency was undesirable. A large number of students wasted time, and a considerable amount of the answer space, just rewriting the information in the table without any comparison other than to quote the numbers given. Specialist terms were usually limited to those given in the question. There was a considerable variation in the ability to use good English; some excellent sentences and clear writing, and at the other extreme an inability even to use capital letters and full stops, and copy correct spellings from words given in the question.E5.(a)???? The correct answer of 35 was rarely given; 8.8 as the resistance for all 4 heating elements was the most common answer. A number of students then incorrectly divided by 4 to find the resistance of a single heating element. These students usually gained a single mark for dividing the p.d. of 230 V by the current of 26 A. The concept of significant figures is still not well understood with very few students scoring full marks.(b)???? (i)??????Very few students scored both marks, however half of students did score one mark. Most answers lacked detail and some made reference to potential difference rather than current. Several students confused current and p.d, writing that 230 V was too high for the wire. Surprisingly few students scored the mark for overheating with many references to plugs / things blowing up and fuses melting rather than the wire.(ii)????? A significant minority of students did not attempt this part question. Many students referred to a plug rather than the cable. Some answers suggested that students were not familiar with what a cable was, except in the context of a ‘cable grip’ in the plug, which made them believe it was the plug that they needed to describe. Very few students scored all three marks, and half of students only scored one mark. The idea of the wires connecting to the pins of a plug was quite common, as were a variety of colours.(c) ????Nearly half of students gained both marks. For direct current, frequent incorrect answers included: ‘the current goes straight to the device’, or ‘straight to the source with no wires’, ‘direct current travels in straight lines’. With regard to alternating current incorrect answers seen frequently included ‘alternating current goes up and down’, ‘only flows in a parallel circuit’ or ‘goes in many directions.’E6.(a)???? A large proportion of the students provided the correct answer of 25 ohms. The most common incorrect response was 5 ohms, achieved by subtracting the numerical values of the resistors.(b)???? (i)??????Almost half of students gained both marks, with very few gaining one mark. Common incorrect answers were achieved by multiplying or dividing the answer to part (a) by 6.(ii)????? Perhaps surprisingly, only just over half of the students knew that the two ammeters would have the same reading.E7.(a)???? (i)??????Only half of the students were able to select the correct value for frequency.(ii)????? Most students could identify the power correctly.(b) ????The majority of students were able to score two marks by selecting the correct equation and calculating the current. However, only a third of students gave the correct unit. Many students failed to either write a unit in the answer space or indicate a choice by circling one of the units in the list.(c) ????Two thirds of students gained one mark by giving a correct pattern linking the time and charge. However very few went on to score both marks by stating that the relationship between the variables was directly proportional.E8.(a)???? (i)??????Considering this question was asking for recall of standard symbols it is surprising and disappointing that over half of the students scored zero. Only a small minority of the students gained both marks. The variable resistor caused fewer problems than the diode.(ii)?????Again poorly answered with only about a third of the students gaining both marks and just less than half of the students scoring zero. Many of the students mentioned the switch and the direction of the diode as a reason for the circuit being incorrect. Others showed even less understanding of the circuit.(b)???? (i)??????The majority of the students gained this mark.(ii)?????Just over half of the students got this question correct gaining the full three marks. A Significant number of students made errors by taking the numbers 0.08, 0.8 or 0.009 from the graph.(c)???? (i)??????Just less than a quarter of students managed to achieve two marks on this question; with a further small number gaining one mark by obtaining the period, with a significant number believing this was the final answer.(ii)????? Very few students achieved both marks on this question – most made no mention of high resistance in the reverse direction. Less than half of the students achieved the second marking point with reference to current flowing only in one direction.E9.(a)???? (i)??????This was poorly answered with about a 50/50 split between the numbers 50 and 230.(ii)????? Just over three quarters of the students failed to score any marks often confusing RCCBs saying they switched off the circuit when the (live) current was too high. Others thought that they worked like fuses with something in them melting at too high a current. Of the minority who scored one mark it was usually obtained by correctly stating that the current in the live and neutral wires differed, but then went on to describe the mechanics of how the device worked rather than giving a reason for the currents being different. The very few who achieved both marks obtained these by linking the current flowing to ground through the earth wire/copper braid but omitted the way the RCCB detected the fault.(iii)???? The majority of students scored this mark for the idea of quicker operation or the ability to reset / reuse RCCBs. Some students gave insufficient detail with answers such as ‘automatic operation’ or ‘safer’ with little exemplification.(b)???? (i)??????Since the equation for this is given it was disappointing how few students managed to use the equation, transform it correctly or substitute values in correctly. Approximately half the students either did not manage to correctly change hours to seconds or did not realise this had to be done.(ii)????? A minority scored both marks on this and very few scored one mark – if students found the correct equation they could put the values in and do the arithmetic. Unfortunately too many students chose the incorrect equation trying to use E = P × t and using p.d. for power rather than E = V × Q. Some students tried to use E = V × I × t but again incorrectly converted hours to seconds. However it was pleasing to see that most students showed the working they used towards getting their answer even though it was often wrong.(c) ????Most students did not appreciate that the thermistor increased in temperature but related the answer to heating the ground. The link between the thermistor and a decrease in resistance was well understood. Weaker students did not understand the way in which a thermistor works or the effect of temperature on its resistance.E10.(a)???? (i)??????This was poorly answered. Just over half of the students could put the ammeter into the circuit correctly but few could add the voltmeter correctly. Common errors included using the wrong symbol and / or placing the voltmeter in series.(ii)????? Just under half of the students gained this mark, usually for adding or subtracting a cell or simply stating ‘change the volts’.(b)???? (i)??????About two thirds of students were able to extrapolate the graph line to obtain the correct value.(ii)?????Those students scoring a mark in part (b)(i) were usually able to go on to score both marks in this part.(c)???? (i)??????About three quarters of students were able to give an acceptable version of the relationship. A significant number of students answered in terms of length rather than thickness as instructed.(ii)????? Many students considered the error to be one of plotting, very few gave an acceptable answer.(iii)???? A majority of students gained the mark for this part.E11.(a)???? This was disappointingly completed for a simple piece of recall. A small number of the students scored both marks and a small number scored one mark. Common errors where one mark was scored indicated that direct current flowed in one direction but alternating could go ‘in any direction’. Many other incorrect responses referred to oscilloscope traces, ‘positive’ and ‘negative’ and frequency.(b) ????A very small number of the students gained both marks and only a small number scored one mark. The main error was for students to recall complete statements about the manner in which a fuse melts with no reference to the kettle. The earth connection was often described as an active component ‘pushing current’, ‘redirecting energy’ and undertaking other functions which indicated a complete lack of understanding.?E12.?????????(a)????? (i)????? The majority of students, over 90%, scored 2 marks. Very few gained 1 mark.(ii)???? Very few students produced a correct graph to gain 2 marks. A large percentage of students did not appreciate the importance of using the answer to part (a)(i). Common “wrong” answers included a straight line from the origin to (12,2), a straight line from (12,2) through (2,0.8) and continued back to the y axis, and two straight lines, one from origin to (2,0.8) and then from that point to (12,2). Otherwise, all sorts of curves, including s-shaped and convex all the way from the origin.(iii)???? There were only a minority of correct answers, less that 25%. Many answers referred to how the resistance changed as the current increased but not why. There were also lots of answers given in terms of the resistance changing to allow or stop the current flowing and for safety to keep the “fuse” from blowing.(b)?????The majority of students gave correct answers. The most common incorrect response was “144”, by multiplying the charge by the time in minutes. An answer scoring one mark was rare – and seemingly from students who did not possess a calculator.???E13.??????????(a)?????(i)????? About two-thirds of students correctly added the resistances together to give an answer of 15.(ii)???? Just under half the students were able to use the answer to part (a)(i) to correctly calculate the reading on the voltmeter. The most common error seen was dividing by the current rather than multiplying by it.(iii)???? Only a third of students scored this mark. Most students thought that using a higher value resistor would cause an increase in the current.(b)???? Only a small minority of students identified Y as being the oscilloscope trace for a d.c. current, with even fewer students stating a correct reason for their choice.???E14.??????????(a)?????(i)????? Just over two-thirds of students scored this mark.(ii)???? Under half of students scored this mark. Incorrect responses were mostly concerned with the efficiency of the apparatus provided, rather than correctly noting that the premier factors were either the relative positions of the LDR and torch or aspects of the surrounding environment where the investigation was undertaken.(b)???? Most students stated the correct relationship between the intensity of the light and the resistance of the LDR to score one mark. However, few achieved the second mark by indicating the numerical decrease of the resistance within the range of light intensity values given in the question.(c)?????(i)????? Few students correctly stated why a line graph was an inappropriate way of displaying the results. Most responses were couched in terms of the lack of results or the range of resistance value.(ii)???? Nearly half of the students correctly agreed that the student's data complimented those values taken from the manufacturer's graph. The reasons for students choosing to disagree were varied and, apart from misinterpreting the data, followed no clear pattern.(d)???? Over three-quarters of students identified the correct circuit.???E15.??????????(a)???? Only just over half of students were able to give an acceptable meaning for electric current. There were many vague answers such as ‘the flow of electricity‘. Very few students, were able to give the meaning of potential difference. Common errors often included the idea of a force pushing the electricity around.(b)???? This question was poorly answered. Very few students referred to free electrons at all. Most students gained one mark for an answer linking the increasing p.d. to the temperature however, few went on to then link this to the resistance increase. A significant number of students thought that the resistance caused the p.d. Those students who tried to explain resistance in terms of electrons colliding more often as the ions vibrate faster found it difficult to express themselves clearly. Many students had ‘start’ to vibrate and ‘start’ to collide, implying this was not happening before. Others had ions moving, rather than vibrating. Some students linked resistance to it being harder for electrons to pass, without giving any explanation why.(c)???? About half the students scored both marks. The most common error was to misread the graph scale when obtaining the current at 6 volts. However, students that did misread the graph could still score one mark by showing a correct calculation using their incorrect value.???E16.?????????(a)??????(i)????? This question was poorly answered with only a third of students completing the calculation correctly. Many students missed the information that the scales contained two cells and so used 3 V in the calculation. A large number of students were unable to convert mA to A. Some students chose the correct equation, but were unable to transpose it correctly. It was extremely disappointing that only a tenth of students were able to give the unit for resistance.(ii)???? This question was poorly answered by most students. Many students made reference to other tissues, such as muscle, but were unable to relate this to changes in body fat or body resistance. Common errors included responses relating to clothing and responses in terms of the inaccuracy of the apparatus or lack of precision.(iii)???? A small number of students correctly identified the water would cause a change in body resistance and so give misleading values. Many students however, took this idea further and suggested a risk of electrocution or internal burns because water was a good conductor. A significant number of students simply stated that you would weigh more because you had drunk the water.(b)?????(i)????? Very few students were able to write that the RCCB works by detecting a difference between the current in the live wire and the current in the neutral wire. However, many students were able to score this mark by giving the alternative answer that the RCCB could be reset. A small number of students were under the impression that an RCCB is a type of fuse or that it contains a fuse inside. Over half of students were able to score a mark by stating that the fuse melts / blows. However, students should be aware that other descriptions such as, breaks, explodes, snaps and bursts are not acceptable.(ii)???? There were few responses where the student had calculated from the graph that the RCCB had to switch off within 60 milliseconds. Many students seemed to have missed the instruction to use information from the diagram or did not understand the significance of the difference in the current in the live and neutral wires. A number of students did gain a mark for the idea that the RCCB was fast, quick or acted immediately. Some students thought that ‘automatically’ was the same as fast. A few students misunderstood the graph and thought incorrectly that the RCCB switched the circuit off faster if the current was higher.???E17.?????????(a)????? (i)????? Most students gave the correct answer. Erroneous responses usually involved dividing by 1.5.(ii)???? Nearly three quarters of students scored this mark.(iii)???? Nearly two thirds of students scored this mark. Incorrect responses were spread equally between the other components joined in series.(b)?????(i)????? Nearly all students now know what an anomalous result is and so scored this mark.(ii)???? Just under half of students realised that the most likely reason for the anomalous result was a misreading of the ammeter.(iii)???? Many students clearly did not understand what was meant by the term ‘interval’. Most students interpreted it as the range of p.d.’s or as the number of small squares on the graph paper between readings or as the p.d. represented by the size of a small square on the graph paper. Many students gave descriptions of what happened to the current as the p.d. was changed.(c)?????This was well answered with a variety of acceptable phrases. Most students described an increase in p.d. leading to an increase in the current. Some students went for a positive correlation, with a few students giving directly proportional. Those students who tried to answer in terms of numerical values were less successful as they often failed to read the current scale correctly.???E18.?????????(a)????? (i)????? Just over three fifths of students recognised the incomplete circuit. However there was a little confusion over how to express the idea. The switches were often described as not being connected, clearly they are connected but not in a position to form a closed circuit.(ii)???? The vast majority of students showed a correct substitution of the two numbers with a subsequent correct calculation.(iii)???? Just over three fifths of students scored this mark. Those students that did not usually thought that the total resistance would go down and so divided by two.(b)?????Just under half of the students were able to express a clear advantage of using two switches. Weaker students expressed ideas such as ‘it’s safer’ or ‘it wastes less energy’ without giving any further detail. Some students read the question as having two bulbs rather than two switches and gave responses such as ‘if one bulb breaks the other will still work’.(c)?????(i)????? This was well answered by nearly all students. Favourite answers were receiving an electric shock or electrocution. A few students interpreted the question as ‘why’ rather than ‘what’ and wrote ‘the earth wire was unconnected’.(ii)???? Just over three fifths of students knew that the earth wire needed connecting. Some students wanted to cover the wires with plastic, whilst others wanted to connect the earth wire to a fuse.???E19.?????????(a)????? (i)????? Excellent responses in most cases, with three quarters of students scoring this mark. The most common error was: ‘current will halve’; the other common error was to simply restate proportionality.(ii)???? This was not well answered with only approximately two fifths of students giving the correct answer. The most common incorrect answer was battery. Other incorrect answers included ‘voltmeter’, ‘resistor’ and ‘diode’.(b)?????(i)????? Nearly three quarters of students gave a good answer; most students wrote ‘data / results’, rather than ‘variables’ being continuous.(ii)???? This was poorly answered, with only one tenth of students giving a correct response. Far too many answers were vague, e.g ‘human error’ or ‘random error’. Similarly ‘misreading meter / voltmeter’ was another frequently incorrect response.(iii)???? There were many excellent straight lines drawn, often with absolute clarity and passing through the origin. There were very few ‘curvy’ lines trying to hit all points. The students who just failed to score the mark often did so by not starting at the origin but at 1V and 0.2 A.(iv)???? Just over a tenth of students scored this mark; many ‘Yes’ answers failed to score the mark because it was simply stated that ‘as voltage increased so did current’ or ’current proportional to voltage” etc. Quite a few correct answers used a mathematical argument well.???E20.?????????(a)????? (i)????? Only a few students scored both marks. The first mark for calculating 30 cells was most frequently scored however the mark for series circuit was rarely given. Appearances of ‘parallel circuit’ were fortunately rare. Those students who did attempt to describe the connection needed for the cells to make a battery said ‘positive to negative’ without realising that this could be achieved both in series and parallel.(ii)???? About three fifths of students could describe a direct current however there were a lot of common misconceptions: a current which goes straight to where it is needed, it flows through all of the circuit, a current which travels in a straight line. A few students tried to describe d.c. only in terms of a CRO display which was insufficient for this question.(iii)???? About a quarter of students scored all three marks. The most common mistake was the failure to convert the time of two hours to seconds. Of the third of students who gained two marks, the majority gave the ‘fall back answer’ of 10 or 600 with the correct unit, those who gained one mark achieved this mostly with answers of 10 or 600 with very few gaining 1 mark from a correct unit without a correct calculation. A number of students had been well trained to put a really large C but unfortunately a number of small c’s and q’s were also in evidence. A few students scored no mark.(b)?????(i)????? This question was well done compared to recent years, with nearly three quarters of students scoring bothmarks. Common mistakes were the failure to square ‘6’, and erroneously changing 120 kg to 120000 g.(ii)???? Most students correctly stated that the distance was reduced (in their own words) but some mistakenly gave an answer of ‘time being less between recharge’ thus not answering the question. A common misconception is that more KE is needed to move the bicycle with a greater load rather than more energy from the battery being transferred as more KE for a bicycle of greater mass moving at the same speed. Very few students who mentioned KE in their answer managed to do so in an appropriate way to score the mark. The two fifths of students who scored the reason mark generally did so by simply stating that ‘more energy is needed’.???E21.?????????(a)????? (i)?????Just under half of the candidates correctly calculated the potential difference across the 3 cells. Common incorrect answers were 6 V and 9 V, perhaps showing that candidates knew from the diagram what to do but did not read the question to know that the p.d. of each cell was 1.5 V.(ii)?????Just over two-thirds of candidates did not appreciate that the p.d. given in part (a)(i) was split equally between the two lamps.(iii)????Again poorly answered with nearly two-fifths of candidates selecting the correct voltmeter.(b)?????(i)????? Most candidates added the two resistor values correctly.(ii)?????Disappointingly, few candidates achieved both marks for this part question. The majority of the candidates simply used their total resistance of 30 ohms and multiplied by 0.4 amps to get 12 volts. However, the question specifically asked for the voltmeter reading across the 20 ohm resistance, alone, as shown in the diagram.(iii)????Surprisingly, few candidates opted for the straight line, most chose option Z.???E22.????????? (a)???? Considering that there are only three I-V graphs that candidates need to be able to identify it was surprising that under half of candidates gained this mark.(b) ????Half of the candidates scored zero for this question. Centres might well consider issuing symbol diagrams photocopied from the specification and encouraging candidates to copy them accurately. Many candidates were able to salvage some marks by correctly drawing a voltmeter in parallel with whatever device they did select, although there were also a large number of short circuits drawn.(c)?????(i)????? Only two-fifths of candidates were able to read the graph correctly. Some misreadings were quite inexplicable.(ii)?????Even those candidates who had not scored a mark in part (c)(i) frequently picked up these two marks by accurately manipulating the equation and pushing the right calculator buttons. It was pleasing to see that most candidates were able to transform an equation. The importance of significant figures was also widely recognised. The commonest mistakes were either inverting the sum or multiplying instead of dividing.???E23.?????????(a)????? (i)?????Less than a quarter of candidates applied the rule for current in a series circuit to arrive at the answer 0.25 A. The vast majority of candidates multiplied the series current by the number of lamps to arrive at an incorrect answer of 5 A.(ii)?????Just under two-thirds of candidates used the equation correctly to gain both calculation marks. About three-tenths of candidates lost one mark because they failed to convert the time from minutes into seconds. Only just over a third of candidates knew that the unit of charge is the coulomb. A substantial number failed to give any unit or offered one of a range of other electrical units.(b) ????Many candidates showed a good understanding of why a piece of aluminium foil is not an appropriate replacement for a fuse, and they could use good scientific language to explain their ideas and gain full marks. Some candidates got sidetracked too far into describing how a fuse functions in a faulty circuit without then going on to say why the aluminium foil presents a danger. Many of the poorer answers were long and rambling, with wrong physics such as ‘too much voltage goes through the foil’, and ‘explosions’ in many of the responses scoring zero. In contrast, some of the best responses covered all four of the possible mark points in a succinct sentence or two.???E24.????????? (a)???? Surprisingly, only just over two fifths of candidates were able to give the correct colour.(b) ????Only a quarter of candidates achieved credit for stating that the plastic obviated the need for an earth wire to be fitted to the hairdryer. Of the incorrect responses, many implied that the whole of the hairdryer was constructed of plastic materials or that the current needed by the hairdryer was so low that an earth wire was not required.(c)?????(i)????? Most candidates were able to identify switch S1?as operating the fan, but only about two fifths of candidates were able to identify the switches needed to operate heater 2.A common error was only giving S3?for the operation of heater 2. Many candidates’ handwriting was such that examiners struggled to distinguish between a suffix 1 and a suffix 2.(ii)?????The majority of candidates scored no marks in this part question. Candidates seemed to be confused about whether the fan part and/or heater parts of the circuit were in series or parallel and how this would affect the different branches of the circuit. Many candidates referred to a ‘fan switch’without making it clear which of the three switches was intended.(d) ????Unfortunately many candidates ignored the request to give the appropriate unit and were thus denied full credit for this part question. Incorrect numerical responses were mostly from the candidates using the wrong current, usually by adding the three currents together from the table supplied. It is not encouraging that the presence of more than two numbers caused such confusion.???E25.?????????(a)????? (i)?????Only about a fifth of candidates scored full marks, with a further two fifths of candidates scoring one mark, usually losing the mark for the misplacing of the voltmeter. Scripts with higher marks usually had candidates drawing the circuits with the use of a ruler. Perhaps using a ruler indicated they would be careful when drawing the components. The most common error was joining both the ammeter and voltmeter in series suggesting a lack of practical experience. Others placed the voltmeter across the wrong component or even across a lead, and some lost marks for careless diagrams, notably lines drawn through meters and gaps in the circuit.(ii)?????Just over half the candidates scored this mark. Many candidates believe that it is thevalue?of d.c. which does not change, and many responses appeared based on the appearance of a.c. and d.c. on an oscilloscope. Another common incorrect response referred to d.c. going straight to the component.(b)?????(i)????? Approximately three quarters of candidates completed the calculation correctly. Weaker candidates struggled to transform the equation.(ii)?????The relationship between current and resistance is, generally, well understood and four fifths of candidates scored this mark. Weaker candidates often used inappropriate language; the use of ‘stronger’ resistance was one such example. Candidates would benefit by using the stem to help their wording; if the word decrease is used in the stem it makes sense to respond with the word increase and not seek synonyms which are less appropriate.(iii)????Many candidates realised that elastic energy is stored but under half of candidates gained the mark since many failed to include the word potential in their answer. The wrong answers often referred to kinetic energy.???E26.????????? (a)???? Virtually all candidates gave the correct answer.(b) ????This question was answered well by the majority of the candidates. However, it was worrying to note that even though candidates are advised that calculators may be used, a significant number of candidates added 18 and 6 to give answers of 23 and 25.(c) ????There were very few correct answers given.(d) ????Most candidates answered correctly. Incorrect responses were principally in terms of division of 6 volts by 0.25 amps.???E27.????????? (a)???? Most candidates chose the correct answer.(b) ????Most candidates were able to achieve 2 marks by stating the relationship between the light intensity and LDR resistance. However, from the brevity of the responses, it seemed that candidates may have disadvantaged themselves by not noting that the mark allocation for this part question was 3 marks and that the question specifically asked for adetailed?description of the relationship illustrated in the graph.(c)?(i)?(ii)???? There was an even spread of candidates choosing from the three options offered in part (c)(i), with very few candidates with the correct answer then giving a valid reason for their choice . Many of the candidates achieved credit in part (c)(ii) by stating that the resistance of the LDR increased because of the fall in light intensity, having previously indicated that they thought the current would increase.(d) ????Most candidates gave the correct answer.???E28.?????????(a)????? (i)?????Surprisingly only just over half of the candidates correctly identified the component as an LDR. Again, this shows that many candidates need to spend time learning some of the basic information contained within the specification. Common errors included; LED, light sensitive resistor, bulb and diode.(ii)?????Most candidates were able to read off 25 from the graph within the tolerance of the mark scheme.(iii)????Most candidates managed to use the equation, however common errors were to use 25 instead of 25000 or failing to convert kilohms to ohms successfully. A small minority of candidates used 20 (from 20 lux) instead of the resistance from part (a)(ii). Less than half of the candidates scored both marks.(b)?????(i)????? This question was poorly answered. Candidates did not seem to put together the information in the circuit diagram with this part of the question and recognise that the maximum voltage available for the circuit was the 6 V supply. The most common scale was 0 to 15 V, which was acceptable for credit.(ii)?????Few candidates demonstrated a good understanding of the operation of the circuit. Many candidates drew a positive gradient line. Comments above for maximum voltage also apply for the line sketched. Of the few candidates who drew a negative gradient line, many lost 1 mark by taking the line above 6 V. However, some candidates scored both marks for the line even though their answer to part (a)(iii) was incorrect.(c)?????(i)????? Just over half of the candidates managed to calculate the correct value. Common mistakes were to use the wrong values from earlier in the question - using their calculated values of voltage from part (a)(iii) or using the 20 from 20 lux.(ii)?????Very few candidates managed to obtain full marks. Precision and accuracy were confused by some candidates; many candidates using ‘it’ lost marks by failing to specify that it was the measurements /values / light intensity that was inaccurate.???E29.????????? (a)???? This question was poorly answered with a small majority of the candidates scoring no marks. In some cases this was due to a lack of knowledge or understanding eg, candidates refer to the attraction of the (positive) boy’s body to the negative dome or to the movement of positive charge / protons / positive electrons.In many instances, a lack of precision in the use of English prevented candidates gaining marks, especially in respect of the second mark point where responses were left at hairs repelling without further explanation. Some candidates referred to hair standing on end as a result of the person getting a shock and others because the charge was trying to escape from the body.(b) ????Under a quarter of the candidates scored 2 marks for a correct calculation. A significant number of candidates scored 1 mark for answers of either 2 or 0.002 as they had not converted the kV or mJ correctly, despite the information in the stem.A number of candidates did not seem to have access to a calculator and had done calculations around the text, sometimes making errors which deprived them of full marks. Of those who did not gain marks, this was evenly spread between those who did not transform the equation correctly and those who did not transform values properly. At this level it is disappointing that over a third of the entry simply multiplied the given numbers; with or without an attempted conversion.(c) ????Only half of the candidates gave the correct answer.?E30.????????? (a)???? Most candidates were able to draw the conventional symbol for a lamp. The most common error was to draw a circuit giving the examiner a choice of several symbols to select from. Only those candidates who made their intention clear by labelling the bulb were given credit.(b)?????(i)????? This part question was answered well with most candidates remembering to use the time in seconds. There were a number of cases where candidates did not use the joulemeter reading provided.(ii)?????Surprisingly only just over three fifths of candidates were able to identify the correct unit.(c) ????This was correctly answered by just over two thirds of candidates.???E31.????????? A large majority of candidates gained at least two marks for this question, with approximately one third gaining full credit.???E32.?????????(a)????? (i)?????While many candidates answered this well, many let themselves down by a poor choice of language or ambiguous statements such as ‘the driver took longer to brake’ which could mean that the braking action occurred over a longer time or that the driver took longer to apply the brakes. Incorrect use of technical terms negated some otherwise correct answers. A minority of candidates also confused the time to see the incident with the time to react to the incident.(ii)?????About three quarters of candidates gained this mark. Again a lack of precision in responses led to ambiguity which lost the mark: mentioning deceleration without specifying that velocity reached zero, stating that they both started from 15 m/s without saying they stopped, and vague statements that the ‘lines were the same’ without quoting gradient, slope or angle. Some candidates demonstrated an inability to take times from the graph with wildly inaccurate values quoted from 1.2 s to ‘nearly 30 s’.(iii)????Few candidates recognised that they only needed to calculate the distance car B travelled in the extra thinking time part of the graph [(1.4-0.6)×15]. The majority of candidates knew that the area under the graph represents the distance travelled and gained marks accordingly. However, calculating these for both cars proved difficult due to the number of calculations involved and errors in obtaining the correct times from the graph. Many candidates did obtain two marks for completing only one of these calculations correctly. About two fifths of candidates failed to gain any marks.(b) ????Some very good answers scored two marks but these were from less than a tenth of the candidates and were usually gained for explaining why X and/or Y were not suitable, rather than why Z is suitable. Most candidates scored one mark for correctly choosing Z but failed to give an acceptable reason. Many candidates clearly did not understand what a sensor was, describing it as a safety device that helped protect people in collisions by counteracting the forces they experienced rather than a device for measuring forces. Some candidates believed the resistance was some sort of resistance to collision, rather than electrical resistance, and made comments such as ‘Z would be better as impact time would be increased’ or ‘the increased resistance would reduce the effect of the collision’.??? ................
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