CLASS - 10



ideal indian school, doha-qatar CLASS - 10PHYSICS - QUESTION BANK2017-2018LIGHT – REFLECTION AND REFRACTION THE HUMAN EYE AND THE COLOURFUL WORLDELECTRICITYCLASSCHAPTER – LIGHT REFLECTION & REFRACTIONONE MARKWhat is the magnification of the images formed by plane mirrors and why ?The speed of light in a transparent medium is 0.6 times that of its speed in vacuum. What is the refractive index of the medium?Find the value of angle of emergence when an incident ray makes an angle of 400 ?with a normal to the air glass interface of the rectangular glass slab.Find the focal length of a convex mirror whose radius of curvature is 32 cm.How does a light ray bend when it travels from i) a denser medium to rarer medium and ii) a rarer medium to a denser medium.Define 1 dioptre of power of a lens.Find the power of a concave lens of focal length 2 m.The refractive index of diamond is 2.42. What is the meaning of this statement ?Arrange the following common substances in the increasing order of refractive indices. Ice, Kerosene, Glass, Diamond, Alcohol, Water.A doctor has prescribed a corrective lens of power + 1.5 D. Find the focal length of the lens. When light undergoes refraction at the surface of two media, what happens to the speed of light?Can absolute refractive index of any material be less than one ?What is meant by power of a lens? State the condition for no refraction of light entering from one medium to another.What is the minimum distance between an object and its real image in case of a concave mirror? TWO MARKSList four characteristics of the images formed by plane mirrors.List four characteristics of the images formed by convex mirrors. With respect to air, the refractive index of ice is 1.31 and that of rock salt is 1.54. Calculate the refractive index of rock salt with respect to ice. Name the type of the mirrors used in design of solar furnaces. Explain how high temperature is achieved by this device.The refractive index of a medium X with respect to Y is 2/3 and the refractive index of medium Y with respect to Z is 4/3. Calculate the refractive index of medium Z with respect to X.The absolute refractive indices of glass and water are 3/2 and 4/3 respectively. If the speed of light in glass is 2 × 108 m/s, calculate the speed of light in (i) vacuum, (ii) water. Write two differences between real image and virtual imageAn object is placed at a distance of 20 cm from a convex mirror of focal length 15 cm. Find the position and nature of the image.An object is kept at a distance of 5 cm in front of a convex mirror of focal length 10 cm. Calculate the position and nature of the image formed.Name the spherical mirror used as : a) Shaving mirror b) Rear view mirror in vehicles c) Reflector in search lights d) Solar furnace.When light enters from air to glass, the angles of incidence and refraction in air and glass are 450 and 300 respectively. Find the refractive index of glass. The image formed by a concave mirror is observed to be virtual, erect and larger than the object. Where should the position of the object be relative to the mirror? Draw ray diagram to justify your answerThe linear magnification produced by a spherical mirror is +1/3. Analysing this value state the i) type of mirror and ii) position of the object with respect to the pole of the mirror. Draw ray diagram to justify your answer.The linear magnification produced by a spherical mirror is – 1/5 . Analysing this value state the i) type of spherical mirror ii) the position of the object with respect to the pole of the mirror. Draw ray diagram to justify your answer.Briefly describe an activity to find approximate focal length of a convex lens.A ray of light incident on a rectangular glass slab immersed in any medium emerges parallel to itself . Draw a ray diagram to justify the statement.The refractive index of a dense flint glass is 1.65 and for alcohol it is 1.36 with respect to air. Find the refractive index of dense flint glass with respect to alcohol.For the same angle of incidence in media P, Q, and R, the angles of refraction are 450 , 350, and 150 respectively. In which medium will the velocity of light be minimum ? Give reason for your answer. THREE MARKSA student wants to project the image of a candle flame on a screen 80 cm in front of a mirror by keeping the candle flame at a distance of 20 cm from its pole. I) which type of mirror should the student use? ii) Find the magnification of the image produced. Iii) Find the distance between the object and the image. iv) Draw a ray diagram to show the image formation in this case and mark the distance between the object and its image.The power of a combination of two lens X and Y is 5D. The focal length of lens X is 15 cm. State the nature and focal length of lens Y.State the meaning of linear magnification. How is it related to object distanceand image distance. ? When is magnification positive or negative ?If the image formed by a mirror for all positions of the object placed in front of it is always virtual, erect and diminished, state the type of the mirror. Draw a ray diagram in support of your answer. Where are such mirrors used and why ?What is lateral displacement of light? Illustrate it with the help of a diagram. List any two factors on which the lateral displacement of a particular substance depends.State the laws of refraction of light . If the speed of light in vacuum is 3 x 10 8 m/s, find the speed of light in a medium of absolute refractive index 1.5.Define power of a lens.The power of a lens is + 2.0 D .i) Find the focal length of lens in m. ii) ii) Name the kind of this lens. Explain with the help of figure whether this lens would converge or diverge a beam of rays.An object of height 6 cm is placed perpendicular to the principal axis of a concave lens of focal length 5 cm. Use lens formula to determine the position , size and nature of the image if the distance of the object from the lens is 10 cm.a)Two lenses have power of i) + 2 D, ii) – 4 D. What is the nature and focal length of each lens? b) An object is kept at a distance of 100 cm from lens of power – 4 D. Calculate the image distance.If the image formed by a lens for all positions of the object placed in front of it is always virtual, erect and diminished, state the type of the lens. Draw a ray diagram in support of your answer. If the numerical value of focal length of such a lens is 20 cm, find its power in new cartesian sign convention.The image of an object formed by a lens is of magnification -1 . If the distance between the object and its image is 60 cm, what is the focal length of the lens? If the object is moved 20 cm towards the lens, where would the image be formed ? State reason and also draw a ray diagram in support of your answer.Rohit wants to have an erect image of an object, using a converging mirror of focal length 40 cm. i) Specify the range of distance where the object can be placed in front of the mirror. Give reasons for your answer. ii) Will the image be bigger or smaller than the object ?iii) Draw a ray diagram to show the image formation in this case.FIVE MARKSa) Explain the following terms related to spherical lens: i) optical centre ii) Centre of curvature iii) Principal axis iv) Aperture v) Principal focus vi) Focal length. B) A converging lens has focal length of 12 cm. Calculate at what distance should the object be placed from the lens so that it forms an image at 48 cm on the other side of the lens.List the sign conventions that are followed in case of refraction of light through spherical lenses. Draw a diagram and apply these conventions in determining the nature and focal length of a spherical lens which forms three times magnified real image of an object placed 16 cm from the lens.At what distance from a concave lens of focal length 20 cm, a 6 cm tall object be placed so as to obtain its image at 15 cm from the lens? Also calculate the size of the image formed. Draw a ray diagram to justify your answer for the above situation and label it.a) Define optical centre of a spherical lens. b) A divergent lens has a focal length of 20 cm. At what distance should an object of height 4 cm from the optical centre of the lens be placed so that its image is formed 10 cm away from the lens. Find the size of the image also.c) Draw a ray diagram to show the formation of image in above situation.a) Under what condition will a glass lens placed in a transparent liquid become invisible?b) Describe and illustrate with a diagram, how we should arrange two converging lenses so that a parallel beam of light entering one lens emerges as a parallel beam after passing through the second lens. c) An object is placed at a distance of 3 cm from a concave lens of focal length 12 cm. Find the i) position ii) nature of the image formed.THE HUMAN EYE AND THE COLOURFUL WORLDONE MARKName two parts of the eye which refracts light rays( or bends light rays)Name the part of the eye : Which controls the amount of light entering the eye Which changes the focal length of eye-lens.What is the name of : a) the curved transparent front surface of the eye b)the light sensitive layer in the eye?Name the part of the retina which is insensitive to light.Out of rods and cones in the retina of your eye: a) which detect colour b) which work in dim lightWhere does the greatest degree of refraction of light occur in the eye?What do the ciliary muscles do when you are focusing on a nearby object?What is the far point of a normal human eye?near point of a normal human eye?Give the scientific names of the following parts of the eye : Carries signals from eye to the brain.Muscles which change the shape of the eye-lensA hole in the middle of the iris A clear window at the front of the eye. What is Tyndall effect?What is meant by scattering of light?Mention the role of optic nerve in the human eye.What is the nature of eye lens of human eye and that of the image formed at the retina of the eye by it?What is power of accommodation?Give an example of a phenomenon where Tyndall effect can be observed?TWO MARKSThe near point of a hypermetropic eye is 50 cm. What is the nature and power of the lens required to enable him to read a book placed at 25 cm from the eye?The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct this problem ?If the earth has no atmosphere, what change would be observed in the length of day . Give reason.No rainbow could be observed from the surface of the moon by the astronauts. Why?i) What is meant by least distance of distinct vision? ii) What is the role of iris in a human eye?Why is the colour of the clear sky blue?Why do we observe random wavering or flickering of the objects near a fire or on a very hot day?Why do stars appear to twinkle? Explain.Give reasons : i) The extent of deviation of a ray of light on passing through a glass prism depends on its colour. ii) Lights of red colour are used for danger signals.What is dispersion ? What happens when light is passed passed through a glass prism?Draw a ray diagram to show the refraction of light through a glass prism. Mark on it a) the incident ray b) the emergent ray c) the angle of deviationWhen is a person said to have developed cataract ? How is the vision of such a person is restored?Why are we not able to see the things clearly when we come out of a dark room ?Why does the sun look reddish at the time of sunrise and sunset ? Explain .Why does it take some time to see the objects in dim light when you enter the room from bright sunlight outside ?In Which of the following two cases the focal length of the eye lens will be more When ciliary muscles of a normal eye is most relaxed.When ciliary muscles of a normal eye is in most contracted state. THREE MARKSWhat is meant by the power of accommodation of human eye ? How does it help a person to see nearby as well as distant objects clearly ? ( or How ciliary muscles help in accommodation?a)What are the values of i) near point ii) far point of vision of a normal adult person? b) A student has difficulty in reading the blackboard while sitting in the last row. What could be his defect of vision ? Draw a ray diagram to illustrate this defect of visioni) Make a ray diagram to show how the eye defect myopia is corrected by using a suitable lens. ii) State two reasons due to which this eye defect may be caused. iii) A person with myopic eye cannot see objects beyond a distance of 1.5 m. What is the power of the lens required to correct the problem?Explain why ? A myopic person prefer to remove his spectacles while reading a book. A hypermetropic person prefer to remove his spectacles while looking at the sky.Write two differences between myopia and hypermetropia.Define the dispersion of white light. Name the colour of light which bends the most the least , while passing through a glass prism . Draw ray diagram to justify your answer.Describe an activity to show that the colours of white light splitted by a glass prism can be recombined to get white light by another identical glass prism. Also draw ray diagram to show the recombination of the spectrum of white light.FIVE MARKSWhat is myopia? State the two causes of myopia. Draw ray diagram for the i) defect of vision ii) correction of myopia.What is hypermetropia? State the two causes of hypermetropia. Draw ray diagram for the i) defect of vision ii ) correction of hypermetropia.An old person finds it difficult to see nearby objects comfortably and distinctly without corrective eye glasses. What defect of vision is he suffering from ? What is it ? List two causes for the development of this defect.What kind of lens will be required to see clearly the nearby as well as distant objects ? Give reasons. How is the eye defect of old reason differing from near- sightedness and far- sightedness?What is atmospheric refraction? Use this phenomenon to explain the following natural events.Twinkling of stars Advanced sunrise and delayed sunset. Draw diagrams to illustrate your answer. a )What is dispersion of white light? State its cause b) “Rainbow is an example of dispersion of sunlight” Justify this statement by explaining, with the help of a labeled diagram, the formation of a rainbow in the sky. List two essential conditions for observing a rainbow.ELECTRICITYONE MARKHow is an ammeter connected in a circuit to measure the current flowing through it.Calculate the current flowing in a circuit if 500 C of charge passes through it in 10 minutes.Define unit volt.What happens to resistance of a conductor when its area of cross –section is increased?A torch bulb is rated at 1.5 V , 500 mA. Find its resistance.A potential difference of 10 V is needed to make a current of 0.02 A flow through a wire. What potential difference is needed to make a current of 250 m A flow through the same wire?The graph between V and I for a conductor is a straight line passing through the origin. i) Which law is illustrated by such a graph ii) which quantity is determined in this graphA current of 200 m A flows through a 4 k ? resistor. What is the p.d across the resistor?If the potential difference between the ends of a fixed resistor is halved, by what factor is the power reduced ?An electric heater is rated at 2 k W. What is the cost of using the heater for 3 hours if the electric energy costs Rs 4 per kWh.Define 1 kWhDefine electric power. Give its SI unitDefine unit watt .TWO MARKSA given length of a wire is doubled on itself and this process is repeated once again. By what factor does the resistance of the wire change?What are the factors on a which the resistance of a conductor depends upon?Work done in moving 5 C of charge across the ends of a conductor is 100 J. If the potential at the other end of the conductor is 10 V, find the potential at the other end of this conductor.Calculate the amount of work done in shifting a charge of 2 C from a point A to B having potentials + 10 V and – 5 V respectively.Write two differences between series and parallel combination of resistances.Draw a schematic diagram of an electric circuit comprising of 3 cells and an electric bulb, ammeter, plug key in the ON mode and another with same components but with two bulbs in parallel and a voltmeter across the combination.How much current will an electric bulb draw from 220 V source, if the resistance of the bulb is 1200 ?? If in place of bulb, a heater of resistance 100 ? is connected to the sources, calculate the current drawn by it.Write two differences between ammeter and voltmeter .An electric heater of resistance 8 ? takes a current of 15 A from the mains supply line. Calculate the rate at which heat is developed in the heater.Define resistivity. Write its SI unit.State Ohm’s law.Keeping the potential difference constant, the resistance of a circuit is doubled. By what factor does the current change in the circuit?A 6 ? resistance wire is doubled up by folding. Calculate the new resistance of the wire.Explain the role of fuse in series with any electrical appliance in an electric circuit. Why should a fuse with defined rating for an electric circuit not be replaced by one with a larger rating?100 J of work is done in transferring 20 C of charge between two points in a conductor. Find the resistance offered by the conductor, if a current of 2A flows through it. i) Explain why tungsten is used for making filaments of electric lamps. ii) Why are the heating elements of bread toasters and electric irons made up of an alloy rather than a pure metal?List two advantages of connecting electrical devices in parallel with the source in domestic circuit.THREE MARKSWhen a current of 4 A passes through a resistor for 10 minutes, 2.88 x 10 4 J of heat is produced. Calculate i) the power of the resistor ii) the voltage of the resistorThe resistance of a wire of 0.01 cm radius is 10 ?. If the resistivity of the material of the wire is 50 x 10 -8 ? m, find the length of the wire.A piece of wire of resistance 20 ohm is drawn out so that its length is increased to twice its original length. Calculate the resistance of the wire in the new situation.The resistance of a metal wire of length 1 m is 10 4 ohm at 200 C. If the diameter of the wire is 0.15 mm, find the resistivity of the metal at that temperature Calculate the heat produced when 96000 coulomb of charge is transferred in 1 hour through a potential difference of 50 V.A potential difference of 250 V is applied across a resistance of 500 ? in an electric iron. Calculate i) current ii) heat energy produced in joules in 10 seconds.Three resistors of resistances 5 ? , 10 ? and 30 ? are connected in parallel to a source of potential difference of 6 V. Calculate i) the total resistance ii) the total current in the in the circuit. iii) the value of current through each resistor.In an experiment to study the relation between the potential difference across a resistor and the current through it , a student recorded the following observations:Potential diff ( V)1.02.23.04.06.4Current I (A)0.10.20.60.40.6On examining the above observations, the teacher asked the student to reject one set of readings as the values were out of agreement with the rest. Which one of the above sets of readings can be rejected? Calculate the mean value of resistance of the resistor based on the remaining four sets of readings. Name the physical quantity which is i) same ii) different in all the bulbs when three bulbs of : a)same wattage are connected in series. b) a)same wattage are connected in parallel. c) a)different wattage are connected in series. d) a)different wattage are connected in parallel.2609850230505Two students perform experiments on two given resistors R1 and R2 and plot the V –I graph shown by diagram 1 and 2. If R1 > R2 which of the diagrams correctly represent the situation on the plotted curves ? Justify your answer.FIVE MARKS QUESTIONS Explain the term : i) Heating effect of electric current. ii )Derive an expression for the heat produced by electric current and state Joule’s Law. iii) Explain why an inert gas like argon is filled in bulbs. a) Though same current flows through the electric line wires and the filament of the bulb, yet only the filament glows. Why? b) The temperature of the filament of bulb is 2700 0 C when it glows. Why does it not get burntup at such high temperature? c) The filament of an electric lamp, which draws a current of 0.25 A , is used for four hours. Calculate the amount of charge flowing through the circuit. d) A electric iron is rated 2 k W at 220 V. Calculate the capacity of the fuse that should be used for the electric iron. Define electric current and write its SI unit. Define 1 ampere of current. In a conductor electrons are flowing from B to A. What is the direction of conventional current? Give justification for your answer. Calculate the number of electrons constituting 1 C of electric charge. ( charge of electron e = 1.6 x 10 – 19 coulomb)a) Calculate the resistance of 1 Km long copper wire of radius 1 mm. Resistivity of the copper is 1.72 x 10 – 8 ? m.b) Draw a circuit diagram consisting of a battery of 4 cells each of 2 V connected to a key, ammeter, and two resistors of 2 ? and 3 ? respectively in series and a voltmeter to measure the potential difference across 3 ?. a ) Define electric power. Express it in terms of potential difference V and resistance R. b) An electric fuse is rated at 2 A. What is meant by this statement ?c)An electric iron of 1 k W is operated at 220 V. Find which of the following fuses that rated at 1 A, 3 A, and 5 A respectively can be used in it. Two conductors A and B of resistances 5 ? and 10 ? respectively are first joined parallel and then in series. In each case the voltage applied is 20 V.Draw the circuit diagram to show the combination of these conductors in each case. In which combination will the voltage across the conductors A and B be the same ? In which arrangement will the current through A and B be the same?Calculate the equivalent resistance for each arrangement.a ) Write two differences between electric energy and electric power. b) Out of 60 W and 40 W lamps, which has higher electrical resistance when in use.c) What is the commercial unit of electric energy? Convert it into joulesi) A 400 W refrigerator operates for 16 h per day. Calculate the cost to operate it for 30 days at Rs 3.40 kWh.ii) A wire of resistivity ρ is stretched to double its length. What is its new resistivity ? Give reasons for your answer. iii) What is meant by the statement that the resistance of the wire is 1 ?.What is meant by potential difference? State its SI unit.i) Name a device that helps to maintain a potential difference across a conductor. ii) Calculate the highest and lowest resistance that can be obtained by the combination of four coils of resistances of 4 ? , 8?, 12 ? and 24 ?. A) Derive an expression for the equivalent resistance of resistors connected in series connection.B) Fuse of 3 A, 5 A, and 10 A are available. Calculate and select the fuse for operating electric iron of 1 k W power at 220 V line. ................
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