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Key TermsUse the spaces below to define the key terms in your own words.3.1Key TermsTextbook DefinitionDrawing / In my own wordsEnergy Chemical Energy Electrical Energy Mechanical EnergyThermal EnergyThermocouple3.2Key TermsTextbook DefinitionDrawing / In my own wordsElectromagnetCommutatorBrushesArmatureDirect CurrentAlternating CurrentTransformersElectromagnetic InductionInduce (Induction)3.3Key TermsTextbook DefinitionDrawing / In my own wordsPowerWattKilowatt HourLaw of Conservation of EnergyEfficiencyChapter 3 – Devices and systems convert energy with varying efficiencies3.1 – Energy Forms and TransformationsEnergyEnergy is defined as the ability to do ________________. It can cause changes to the ____________________, _________________, ________________ or direction of an object. () There are four common types of energy:_________________________________________________________357695569215___________________Chemical EnergyThe energy ______________ in chemicals. This is a form of potential or stored energy. It is released when chemicals react.A common molecule used for the production of energy in humans is _________________, a type of sugar (remember Unit C?!?!). Your cells use glucose molecules and a series of chemical reactions to convert the chemical energy stored in glucose into thermal and mechanical energy.Chemical energy from batteries can be __________________ to electricity and then sound. Part of the mechanical energy used to demolish this building came from the chemical energy stored in explosives. The rest comes from gravitational potential energy.Electrical Energy4109085375285Electrical energy is the energy of _______________ particles. Electrical energy is transferred when __________________ travel from one place to another. Mechanical EnergyThe total energy possessed by an object because of its motion or its potential to move. A thrown baseball has ______________ energy because of its movement and its potential to fall. Potential Energy3787775-451485______________ energy that can be converted to other, useful formsKinetic EnergyEnergy due to _______________ ()-60325194945Thermal EnergyThe total __________________ energy of all the particles in a substance. 2592705955675The _______________ a particle moves, the more kinetic energy it has; this also means it has more thermal energy (heat). If you were to compare two cups of coffee holding equal amounts of liquid, the one feeling warmer is the one that has the faster moving particles.Transformations Involving Chemical and Electrical EnergyYou can use various devices to ________________ electricity into other forms of energy. Electricity can be transformed into any other type of energy, such as heat, light, sound, or movement (mechanical energy). A ____________________ is a device that can convert thermal energy into electrical energy. It consists of two different metals joined together that ____________________ heat at slightly different rates. When the metals are heated, this difference results in electricity flowing from one metal to the other ( (1 min)). Devices such as heaters and ovens do the opposite of a thermocouple; they convert electrical energy into thermal energy. The ____________________ flow through a metal and heat up the metal, releasing heat. Assignment – C+R Pg. 323What is energy?What energy transformations take place in each of the following devices?Electric kettleBattery-operated toy carElectric blanketCordless telephoneWhat does a thermocouple do?What is thermal energy?What is the difference between mechanical and chemical energy?a) What form of energy is found in sugar?b) How is that energy used in your body?A model rocket uses a flammable fuel to power its flight into the air. What energy transformation takes place in the rocket?In what way is an electric oven the opposite of a thermocouple?Why is a thermocouple a good device for indicating the temperature in a car engine?3.2 – Energy Transformations Involving Electrical and Mechanical EnergyElectric MotorsMany of the electrical devices we use everyday contain a ________________________. This important energy converter can be traced back to the early 1800s. In 1820 Hans Christian ______________________ discovers that current flowing through a wire creates a _____________________ field around the wireDemo – deflection of compass needle around conducting wire 5184140635635Later on, Michael _______________________ constructs a device which uses ___________________________ forces to move an object. This was effectively the first motor. It didn’t work very well, nor did it produce a lot of power, but it showed that ______________________ could produce continuous ___________________. Running electric _______________________ through a wire creates a magnetic ______________. Using this simple principle, many useful devices, such as motor and stereo speakers have been developed. The magnetic field around a wire is ______________________ and continuous.-77787519050In a piece of wire, the magnetic field generated does not become particularly ___________________. If the wire is _______________ around an object (such as a nail), the lines of the magnetic field overlap and the overall field becomes much stronger. The more ___________________, the more overlapping, and the ________________________ the magnetic field. The nail becomes an _________________________________ when current runs through the wire. The stronger the magnetic field, the stronger the magnet. However, when the electric current is stopped, the magnetic field collapses, and all magnetic attraction is lost.An electric motor uses electric energy to make a coil of wire spin between the poles of a magnet (the “_____________________________”). This occurs because the coil (armature), is connected to a source of electric energy. Current flowing through the coil turns into an _____________________________, which is rotated by magnetic forces from the field magnet. The fundamental law of all magnets- opposite poles ________________ and like poles ______________- is the basis upon which electric motors function.36499802562860Direct and Alternating CurrentIn one common design for ________________ current (DC), a rotating wire coil (____________________) becomes an electromagnet as current flows into it through a split ring _________________________. The armature is attracted and repelled by stationary field magnets near it, so it begins to _________________. The commutator acts as a __________, cutting off then reversing the direction of current flow to keep the armature turning._____________________ Current (AC) - electricity flows back and forth 60 times per second. Large electric _________________________ in power stations produce alternating current for us in homes and industry. ___________________________ are used to “step up” the voltage for efficient transmission over long distances. At the destination, other transformers “step down” the voltage to the 240/120 V used in homes and factories.GeneratorsElectric currents can produce ______________________ effects. The opposite process is also possible. Electric effects can be produced using a magnet. Michael Faraday and an American scientist named Joseph Henry made this discovery in 1831. 3866515-26670Working independently, they found that a __________________ developed in wires that were ___________________ at an angle to a nearby __________________. The same thing happened when the magnet is moved at an angle to a stationary wire. This process is know as _________________________ ______________________. (Demo – moving a magnet through a coil of wire)Electric _____________________ use the relationship between magnetic fields and electric charges to cause charges to move. Any ____________________ electric ____________________ generates a magnetic field, and any moving magnetic field also causes the movement of an electric charge. Within a generator, a series of magnets is connected to a ______________________ driven by some other energy ______________________ (wind, flowing water, steam, etc.). The magnets in the generator spin relative to a coil of conducting wires. The current then leaves the generator to be used by devices connected to it or it enters the power grid for distribution to a wider area.Assignment – C+R Pg. 331Use words and a drawing to describe how to construct a simple electromagnet.Explain the function of the permanent magnets in an electric motor.Describe Faraday’s contributions to the development of the motor and the generator.A generator stores electric current. Explain why you agree or disagree with this statement.How are electricity and magnetism related?The permanent magnets of a motor are replaced with more powerful ones. What effect do you thing this would have on motor rotation? Explain.You are lost with a group of friends in the deep woods. You notice that the group of leader is determining direction with a compass that is taped to the top of his flashlight. Explain why this is a concern.A motor and a generator are the same thing. Explain why you agree or disagree with this statement.3.3 – Measuring Energy Input and OutputPower2978150431800Power is the ________________ at which energy is __________________ or ____________________. Power tells you how ___________ the energy is being used or produced. If a machine uses 1 Watt of power, it uses one joule of energy in one second. Power=Energy transferrredtime taken For example, an electric hair dryer that uses 1500 joules of energy every second would be rated at 1500 watts.A light bulb that uses 60 joules of energy every second would be rated at 60 watts. Math ConnectExample:A generator produces 60 J of electric energy in thirty seconds. How many watts of power does it produce?An aquarium light bulb uses 21 J of electric energy in three seconds. What is the power rating for the light bulb?Speakers on a computer use 240 J of electric energy in 6 seconds. How many watts of power do the speakers consume each second?What do we buy from power companies?The ______________________ of electric energy is measured in _____________. Usually, when you use power you are using it over an extended period of time. energy=power×time1 watt hour W?h=1 watt ×1 hourMath ConnectExample:How much electric energy does a 40 W light bulb use if it is left on for two hours?How much electric energy does a 150 W light bulb use if it is left on for three hours?How much electric energy does a 240 W fan use if it is left on for two hours?Kilowatt Hours The watt hour is a ___________ unit of energy. Electric utility companies use a unit of energy ___________________ larger, the kW?h. 1 kW?h = 1000 W?hMath Connect – Pg. 110Example:A small kettle is rated at 1000 watts. This means that it uses 1000 watts for each hour it is used. During one week, it is used for two hours. How much energy does it use in kilowatt hours?How much electric energy (in watt hours) does a 1500 W table saw use when run for 3 hours?How much electric energy does a 255 W colour television use if it is on for 4 hours? Give your answer in kilowatt hours.5307330340995If you measured the electric energy (or energy) that goes into a system, and compare it to _________ the forms of ____________________ energy, you will always find that they are equal.Law of Conservation of EnergyEnergy cannot be _____________________ or _________________________; it can only be _________________________ from one type to another.Energy does not just _________________________, if some energy seems to be missing, it is because you have not identified all forms of energy present. Energy DissipationMost often the missing energy is lost or dissipated as ______________. Mechanical systems dissipate energy to their _______________________, and all the “missing” energy is transformed into energy you cannot use. Incandescent light bulbs are designed to convert ________________ energy into _____________. Incandescent means “glowing with heat”These bulbs produce light when _______________________ flowing through a wire makes the wire _______. Some electricity is converted to ________________, most of it is converted to other types of energy, such as _______________. EfficiencyEfficiency is a measure of how completely ________________ energy is ______________________ to _____________________ energy. Incandescent bulbs and fluorescent bulbs produce about the same ____________________ of light; however, incandescent bulbs produce much more ________________, which is wasted. Therefore, incandescent light bulbs are much _______________ efficient than fluorescent bulbs. 4003675250825Math ConnectExample:An electric kettle uses input energy of 240 000 joules to heat water. 196 000 J is actually used to heat the water. Calculate the efficiency of the kettle.An incandescent light bulb uses 30 000 J of electric energy. It emits only 900 J of useful energy. What is the efficiency of the light bulb?An electric motor has 100 J of electric energy supplied to it every second. It produces 70 J of kinetic energy every second when it is providing power to a water pump. What is the efficiency of the motor?Assignment – C+R Pg. 338What is the difference between energy and power?What energy conversions take place in an electric motor?What is the law of conservation of energy?A vehicle is only 15% efficient. What happened to the other 85%?Compare the energy efficiency of incandescent and fluorescent bulbs.You bake a potato in a 1200 W toaster oven for 25 min. How many joules of electricity did the toaster oven use? How many kilowatt hours did it use?A colour TV draws 1.5 A when connected to a 120 V outlet. What is the power rating of the TV set?A diesel truck produces 47.5 kJ of useful output energy from 125 kJ of diesel fuel. What is the truck’s efficiency?A small tractor is 12% efficient at producing useful output from input fuel. How many joules of input energy will this tractor need to produce 1000 J of useful output?Explain the advantage of operating a motor vehicle that is 20% efficient instead of one that is 10% efficient.3.4 – Reducing the Energy Wasted by DevicesDevices which have an energy-_______________________ design are an important consideration for the consumer, because these devices use less _________________________. Energy costs _________________ and it also affects the __________________________________, so reducing energy consumption is a good practice.Limits to EfficiencyElectric heaters come very close to being 100% efficient, but devices that convert electricity to other forms can never be ___________ efficient. Some energy is _________, or dissipated in a form that is not _______________ output. ____________________ causes _________________ energy to be lost, or dissipated in many devices.Increasing EfficiencyIncreasing the efficiency of a device depends on its _____________________. Most devices convert electric energy to ___________________________ energy, where the worst “offender” of waste energy is _____________________. The easiest way to ________________________ the efficiency is to _______________________ the friction in these devicesFor devices that __________________ heat energy, _________________________ is the way to goThink about your ovenEven the fridge – to prevent heat from getting in, you would insulate the fridge better Assignment – C+R Pg. 342Give two reasons for reducing energy waste.What is the purpose of the EnerGuide label on appliances?How can a more efficient appliance benefit the environment?Why are electric motors more efficient than combustion engines?What causes most energy loss in devices designed to produce mechanical energy? What can be done to avoid it?Is it always a good idea to discard low-efficiency devices? Explain your answer.Explain how you might change the design of a typical gasoline-powered lawn mower to increase its efficiency.An electric-assist bicycle has a rechargeable battery and electric motor that can be used instead of pedalling. What type of design features and maintenance suggestions would you recommend to keep an electric-assist bicycle operating at peak efficiency?Section Review – Pg. 343You overhear someone say, “An electric heater does the opposite of a thermocouple.” Is this an accurate statement? Explain your answer.What is the function of the brushes in an electric motor?What is the function of the permanent magnets in an electric motor?What energy transformations take place in the following devices: a dishwasher, a DVD player, a stereo speaker, and a hot-glue gun?Two sisters own stereos. Joleen has a 40 W mini-system. Julianna has a large 120 W system. Is it possible for Julianna system to use less energy in a month than Joleen’s? Explain your answer.A computer plugged into a 120 V outlet draws 3.0 A of current. How much power is the computer using?A chemical laser in a research laboratory can fire for 10 s with a power of up to 10 MW. What is the maximum energy this laser would use when it fires?A 330 W hot plate produces 38 kJ of thermal energy while operating for 2 min. What is the efficiency of this device?You have designed and built an electric golf cart, but it goes only halfway around the course before running out of power. Describe modifications you could make to improve the range of your golf cart.Your brother replaces the electric razor he purchased last year with a new, more energy-efficient model in order to save on his power bill. What does energy-efficient mean? Was this razor a wise purchase? ................
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