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ICSE Class X Question Bank 2024 : Physics MCQs with Answers (Force, Work, Energy, Machines, Refraction, Spectrum)

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Force: 1. When a force acts on _______________ body, the body goes in linear motion. A. Stationary rigid body. B. Stationary flexible body. C. The pivoted rigid body. D. None of the Above. Ans: A. 2. When a force acts on _______________ body, the body goes in rotational motion. A. A rigid body pivoted at a point. B. Stationary flexible body. C. The pivoted rigid body. D. None of the Above. Ans: A. 3. S.I. Unit of moment of force is, A. newton meter. B. N m. C. Dyne cm. d. Kgf m. Ans: A. 4. The rotation is always produce by a A. Applied force. B. Pair of forces. C. Pull and push. D. All of the above. And: B. 5. A book kept on a table is an example of, A. Dynamic equilibrium. B. Static equilibrium. C. Both. D. None. Ans: B. 6. A body is said to be in equilibrium when, A: It does not move. B. It has equal forces on both the sides. C. When the algebraic sum of moment of all forces acting on the body is zero. D. When body is balanced in all sides. Ans: C. 7. A body is pivoted and a force of 20 N is applied at a distance of 60 cm from the pivot. The moment of the force is, A. 12 N B. 1200 N. m C. 12 N m. D. 1200 N cm. Ans: B. 8. Calculate the moment of force F1 at O A. 10 N m clockwise. B. 10 N m anticlockwise. C. 12 N m clockwise. D. 12 N m anticlockwise. Ans: B. 9. Two forces each of magnitude 10N act vertically upwards and downwards respectively at the two ends A and B of a uniform rod of length 4m which is pivoted at its mid-point O as shown. Determine the magnitude of resultant moment of forces about the pivot O. A. 40 N m anticlockwise. B. 40 Nm (clockwise). C. 0. D. 80 N m Anticlockwise Ans: B 10. The factor on which the position of centre of gravity of a body depend, A. Its shape i.e. on the distribution of mass. B. It does not depend upon shape but only on size. C. Position on the earth. D. All. Ans: A. 11. When a boy weighing 20 kgf sits at one end of a 4m long see-saw, it gets depressed at its end. He can be brought to the horizontal position by a man weighing 40 kgf by applying the force at A. 2 m. B. 1 m. C. 2 cm d. 4 m Ans: B. 12. The center of gravity of a circular ring is A. On the ring. B. At half the distance from the center. C. At the center of the ring. D. None of the above. Ans: C. 13. The centre of gravity of a hollow cone of height h is at distance x from its vertex where the value of x is: (a) h/3 (b) h/4 (c) 2h/3 (d) 3h/4 Ans: C. 14. The centripetal force is defined as the A. Force acting on a body moving in a circular path, in a direction towards the centre of circular path. B. The force acting on a body moving in a circular path, in a direction away from the centre of circular path. C. The force acting on a body moving in a circular path, tangent to the circle. D. None. Ans: A. 15. This force is fictitious force. A. Moment of force. B. Centrifugal force. C. Centripetal force. D. Electrostatic force. Ans: B. 16. Which of the following quantity remains constant in uniform circular motion: (a) Velocity (b) Speed (c) Acceleration (d) Both velocity and speed Solutions: Ans: D. 17. The moment of force is a A. Scalar quantity. B. Vectar Quantity. C. Non measurable quantity. D. None. Ans: B. 20. One of the factors affecting the turning effect of a force. A: The magnitude of the energy applied. B. The magnitude of the force applied. C. The magnitude of the gravity working. D. The friction between the moving parts. Ans: D. 21. The disc will rotate in A. Circular direction. B. In the direction of the applied force. C. Clockwise moment. D. Anticlockwise moment. Ans: D. 22. The moment of force about a given axis depends: (a) Only on the magnitude of force (b) Only on the perpendicular distance of force from the axis (c) Neither on the force nor on the perpendicular distance of force from the axis (d) Both, on the force and its perpendicular distance from the axis. Solution: Ans: D. 23. A body is acted upon by two unequal forces in opposite directions, but not in the same line. The effect is that: (a) The body will have only the rotational motion (b) The body will have only the translational motion (c) The body will have neither the rotational motion nor the translational motion (d) The body will have rotational as well as translational motion. Solution: Ans: D. 24. A nut is opened by a wrench of length 20 cm. If the least force required is 5.0N, find the moment of force needed to turn the nut. A: 0.5 Nm B. 1 N m. C. 10 N cm. D. 100 N cm Ans: B. 25. The diagram shows a uniform bar supported at the middle point O. A weight of 40 gf is placed at a distance 40cm to the left of the point O. How can you balance the bar with a weight of 80 gf? A: 40 cm from 0. B. 20 cm from 0. C. 40 cm from 50 cm on the left side. D. At the center of gravity. Ans: B. 26. It is easier to turn the steering wheel of a large diameter than that of a small diameter because, A. To turn the steering wheel of a large diameter need less force which is at a large distance from the centre of rim. B. To turn the steering wheel of a large diameter need negligible force which is at a large distance from the centre of rim. C. To turn the steering wheel of a large diameter maximum force which is at a large distance from the centre of rim. D. large wheels can turn easily. Ans: A. 27. A jack screw is provided with a long arm A. Trucks need more powerful jack screw. B. Long arms can easily reach the interior of the wheel. C. A long arm of a jack screw which is used to lift a heavy load like a vehicle will help to apply less effort which is required to rotate it to raise or lower the jack. D. All of the above. Ans; C. 28. A _____is always required to produce the rotation. A: Energy. 2. Force. C. Couple. D. All the above. Ans: C. 29. ____________ is always taken to be positive. A. Clockwise moment. B. Anticlockwise of moment. C. Moment of force. D. Principle of moment. Ans: B. 30. The center of gravity of triangular lamina lies at A. Midpoint. B. The midpoint of interaction of medians. C, At 3/4th h. D. At the 1/4th h of the median. Ans: B. Work, Energy and Power 1. The diagram shows a pendulum The pendulum swings from P to Q to R and back to P. P is 10 cm higher than Q. At which speed does the pendulum bob pass through Q? A 0.44 m / s B 1.0 m / s C 1.4 m / s D 2.0 m / s Ans: C 2. A crane on a building site lifts bricks of total mass 200 kg, initially at rest on the ground, with uniform acceleration. When the bricks are 5.0 m from the ground, they have a speed of 5.0 m / s. How much work is done during this process? A 2.5 kJ B 10.0 kJ C 12.5 kJ D 35 kJ Ans: C 3. Which device is designed to convert chemical energy into kinetic energy? A an a.c. generator B a battery-powered torch C a car engine D a wind-up mechanical clock Ans:C 4. Which two physical quantities must be used to calculate the power developed by a student running up a flight of steps? A force exerted and the vertical height of the steps only B force exerted and the time taken only C work done and the vertical height of the steps only D work done and the time taken only Ans: D 5. Which quantity is measured in newtons? A energy B mass C weight D work. Ans 6. A lorry of mass 4000 kg is travelling at a speed of 4.0 m / s. A car has a mass of 1000 kg. The kinetic energy of the car is equal to the kinetic energy of the lorry. What is the speed of the car? A 2.0m/s B 4.0m/s C 8.0m/s Ans: C D 16.0m/s 7. Three boxes each weigh 100 N. A man lifts all the boxes together from the ground on to a shelf that is 1.5m above the ground. The man takes 2.0s to do this. How much useful power does the man produce to lift the boxes? A 75W B 225W C 300W D 900W Ans: B 8. A car has a mass of1000kg and a momentum of 12000kgm/s. What is its kinetic energy? A.6kJ B.12kJ C.72kJ D.144kJ Ans: C 9.A cyclist travels down a hill from rest at point X, without pedalling. The cyclist applies his brakes and the cycle stops at point Y Which energy changes have taken place between X and Y? A gravitational potential kinetic thermal (heat) B gravitational potential thermal (heat) kinetic C kinetic gravitational potential thermal (heat) D kinetic thermal (heat) gravitational potential Ans: A 10. To calculate the power produced by a force, the size of the force must be known. What else needs to be known to calculate the power? Ans: A 11. A car is stationary at the top of a hill with the engine switched off. The brakes are released and the car rolls down the hill. At which labelled point does the car have the greatest kinetic energy? Ignore friction. Ans: C 12. A helicopter takes off from the ground and rises vertically. It then hovers at a constant height above the ground. Which sequence of energy changes takes place during the gain in height? A chemical gravitational potential kinetic B chemical kinetic gravitational potential C gravitational potential chemical kinetic D kinetic chemical gravitational potential Ans: B 13. In a hydroelectric power station, one form of energy is stored in a lake or reservoir. This energy is then transferred in stages to another useful form, which is the output. Which row gives the name of the stored energy and the name of the output energy? Ans: C 14. Which movement will require the greatest amount of work to be done? A. A force of 10N moving an object a distance of 3.0m B a force of 10N moving an object a distance of 5.0m C a force of 15N moving an object a distance of 3.0m D a force of 15N moving an object a distance of 5.0m Ans: D 15. A student does some work by pulling a suitcase along a corridor. She now pulls a second suitcase along the corridor. Which row iindicates that the student is now doingg twice as much work? Ans: C 16. Two farmers use an electrically powered elevator to lift bales of hay. All the bales of hay have the same mass. As sunset approaches, they increase the speed of the motor so that more bales are lifted up in a given time. How does this affect the work done in lifting each bale and the useful output power of the motor? Ans: D 17. A force F moves a load from the bottom of a slope to the top The work done by the force depends on the size of the force, and on a distance. What is this distance? Ap Bq Cr D p +q Ans: C 18. When the displacement along the same direction of the force. Then the work is said to be__________ (A)Negative (B)Positive (c)Zero (D) infinitive Ans: C 19. What amount of work is done by a centripetal force in a circular motion? (A)+1 (B) -1 (C) 0 (D)None of these Ans: C 20. When the displacement along the opposite direction of the force. Then the work is said to be__________ (A)Negative (B) Positive (C) Zero (D) Infinitive Ans: A 20. 1 Joule = _________ erg. (A) 105 (B) 107 (C) 10-7 (E) 106 Ans: B 21. Find the correct relation (A) Power = Force/ Velocity (B) Power = Velocity / Force (C) Power = force x velocity (d)Power = force x acceleration Ans: 22. A girl weighting 50 kg climbs up 60 steps each of 20 cm height in 5 minutes. Calculate the power developed. (i) Calculate the work done by the girl (A) 600 J (B) 60J (C ) 6.0 J (D) 6000J Ans; D (ii) Calculate the power developed. (A) 2 W (B) 22 W ( C )2.2 W (D) 20 W Ans; D 23. How fast should a boy weighting 30 kg run so that his kinetic energy is 375 joule? (A)5m/s (B) 25m/s ( C ) 2.5m/s ( D )30m/s Ans; A 24. The truck has to apply a force of 3000 N to overcome friction while moving with a uniform speed of 36 kmhr-1. What is the power developed by the truck? (A) 108000 W (B) 30000W (C) 1080W (D) 30W Ans: B 25. A bullet is of mass 'm' g and is moving with a velocity 'v' m/s. Find the kinetic energy of the bullet when the velocity is doubled. (A) 2mv2 (B) 1/2mv2 (C) mv2 (D) None of these Ans; A 26. Which of the following device converts chemical energy in to electrical energy? A. Battery B. Loud Speaker C. Solar Cell D. Electric Motor Ans; A 27. The conversion of part of energy into undesirable form is called -------------(A) Disintegration of energy (B) Degradation of energy (C) Disposal of energy (D) none of these Ans; B 28. The energy possessed by a body due to its position is called: A. Kinetic Energy B. Potential Energy C. Mechanical Energy D. Electrical Energy Ans: B 29. The commercial unit of Energy is: A. Watt B. Watt-hour C. Kilowatt-hour D. Kilowatt Ans; C 30. In 1 minute how much energy does a 100 W electric bulb transfers? A. 100 J B. 600 J C. 3600 J D. 6000 J Ans: D. Machines: MCQ Std-10 Q1. A movable pulley is used as a. force multiplier b. speed multiplier c. to change the direction of effort d. all the above Ans-a Q2. A woman draws water from a well using a fixed pulley. The mass of bucket and water together is 7kg. The force applied by the woman is 80N. What is the mechanical advantage ? (Take g=10ms 2) a. 0.875 b. 0.75 c. 0.0875 d. 0.815 Ans-a Q3. What is the mechanical advantage of the block and tackle used to lift the bale of cotton? a. 5 b. 2 c. 3 d. 4 Ans-b Q4. If we ignore friction, which of the following two pulleys systems will require less effort (force) to lift the load? a.) Pulley A b.) Pulley B c.) Both Pulley A & Pulley B will require the same effort (force) d.) Not enough information to decide Ans-b Q5. You use a fixed pulley to lift a watermelon to your tree house. If you changed it to a movable pulley and ignore the effects of friction: The effort (force) required would: a.) Increase b.) Decrease c.) Stay the same d.) Not enough information to decide Ans-b Q6. When a fixed pulley is used to lift a load the effort needed is 30N, what is the effort required to lift it using a single movable pulley system? a. 5N b. 30N c. 15N d. 300kg Ans-c Q7. What is the direction of pull in a single movable pulley? a. upward b. downward c. to the right d. none of the above Ans- a Q8. What is the distance the effort moved with a single movable pulley lifting a load by 5 cm? a. 5cm b. 10cm c.15cm d. 4.8N Ans-b Q10. How many ropes are holding up the load in a single movable pulley? a. 1 b.2 c. 3 d. 4 Ans-b Q11. If the mechanical advantage of a simple machine is 4, then the a. output force is 4 times the effort b. effort is 4 times the output force c. efficiency is 4% d. the work output is 4 times the input Ans-a Q12. The ratio of the work output to the work input of a machine is a. Mechanical advantage b. efficiency c. work d. power Ans- b Q13. The mechanical advantage for a pulley system is determined by a. counting the number of strands holding the resistance force. b. counting the number of strands holding and not holding the resistance force c. adding the radii of the pulleys. d. multiplying the radii of the pulleys. Ans-a Q14.In the following pulley system an effort applied is 50N , it can lift maximum load of a. 25N b. 50N c. 100N d. 200N Ans-c Q15. Mechanical advantage is _______________. a. load / effort b. effort / load c. efficiency / velocity ratio d. velocity ratio/ efficiency Ans-a Q16. The actual mechanical advantage of a machine a. cannot be less than 1 b. decreases as the input (effort) distance increases c. increases with greater friction d. is less than the ideal mechanical advantage of the machine Ans-d Q17. A mechanical device requires 420 J of work to do 230 J of work in lifting a crate. What is the efficiency of the device? a. 55% b. 183% c. 190% d. 0.5% Ans-a Q18. The efficiency of a machine is always less than 100 percent because a. the work input is too small b. the work output is too great c. some work input is lost to friction d. a machine cannot have MA greater than 1 Ans-c Q19. In the following pulley system if the weight of movable pulleys is increased then mechanical advantage will _ the a. increase b. decrease c. remain the same d. none of the above Ans-b Q20 . In the following pulley system, if M= 40kg then F=_______( ignore the effects of friction )( Take g=10ms 2) a. 100kg b.100N c. 4kg d. 4N Ans- b Refraction of light 1. Will there be any change in nature and size of the image formed in : Case a) image is formed when the object is placed between its optical centre and principal focus and Case b) image is formed when the object is placed between F and 2F, if the convex lens is replaced by a concave lens of same focal length? A. B. C. No Yes. Depends on colour. D. Depends upon distance 2. When two lenses 10D and - 20D are kept in contact find focal length. A. B. C. D. 3. - 9 cm 10 cm 11 cm 12 cm A ray of light passes from glass into air. The angle of refraction will be __________ angle of incidence. A. Equal to the B. Greater than the C. Smaller than the. D. None 4. Which of the following is correct order of the increasing refractive indices? A. B. C. D. Ice, water, alcohol, kerosene, glass, diamond Ice, water, alcohol, kerosene, diamond glass Water, ice, alcohol, kerosene, glass, diamond Kerosene, ice, water, alcohol, glass, diamond 5. When a straight stick is partly immersed in water and held obliquely to the surface, it appears to be bent at the point where it enters water. Does the stick actually bend? A. Yes, it does. B. No, it is just refraction of light which causes this apparent bend. C. Depends on density of water. 6. Assertion (A): Light travels faster in glass than in air. Reason (R): Glass is denser than air. A Both A and R true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true. 7. Sudha finds out that the sharp image of the window pane of her science laboratory is formed at a distance of 15cm from the lens. She now tries to focus the building visible to her outside the window instead of the window pane without disturbing the lens. In which direction will she move the screen to obtain a sharp image of the building? A. Away from the lens B. Towards the lens 8. The ratio of the height of the image to the height of the object is called ____________. A. demagnification B. magnification C. diminishing D. none of the above 9. In order to obtain a magnification of ( 3) with a convex lens, object should be placed : A. Between optic centre and focus B. Between focus and 2F C. At 2F D. Beyond 2F 10. Does higher optical density mean higher mass density? A. Yes B. No c. Yes as well as no. 11. When two lenses 10D and 5D are kept in contact find the effective focal length of the combination. A. - 9 cm B. 10 cm C. 20 cm D. cm 12. Which of the given expressions is correct? A. Absolute refractive index = 2 B. Absolute refractive index C. Absolute refractive index = D. Absolute refractive index = = 13. A 10 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 12 cm. The distance of the object from the lens is 18 cm. Find the position of the image formed. A. 36 cm on the other side of the lens B. 37 cm on the other side of the lens C. 38 cm on the other side of the lens D. 39 cm on the other side of the lens 14. What would be relative size of the image formed by convex lens when the object is placed between F and 2F? A. Highly diminished (point sized) B. Enlarged C. At Infinity D. Infinitely large (highly enlarged) 15. A in which light travels comparatively slower than the other medium is called a ______ medium. A. Co-optically rarer B. Co-optically denser C. Optically rarer D. Optically denser 16. The refractive indices of four substances P, Q, R and S are 1.77, 1.50, 2.42 and 1.31 respectively. When light travelling in air is incident on these substances at angles, the angle of refraction will be the maximum in : A. P B. Q C. R Q. S 17. ________ is a piece of transparent medium bounded by two surfaces of which at least one surface is curved. A. Lens B. Mirror 18. When light is travelling from one medium (other than vacuum or air) to another medium, then the refractive index of the latter is called __________ A. Refractive index of medium 1 with respect to medium 2 B. Absolute refractive index C. Relative refractive index 19. What would be the relative size of the image formed by a convex lens when the object placed at infinity? A. Highly diminished (point sized) B. Enlarged C. Diminished D. Infinitely large (highly enlarged) 20. When the refractive index of a medium relative to lens is 1, a convex lens will behave as an ordinary glass plate. A. Yes B. No 21. What is the speed of light in a medium of refractive index 00, 000 km/s? 6 5 if its speed in air is 3, A. 2, 00,000 km/s B. 3, 60,000 km/s C. 4, 00,000 km/s D. 2, 50,000 km/s 22. A student obtains a blurred image of a distant object on a screen using a convex lens. To obtain a distinct image on the screen he should move the lens : A. Away from the screen B. Towards the screen C. To a position very far away from the screen D. Either towards or away from the screen depending upon the position of the object 23. When the object is placed at the focus of a convex lens, the rays of light refracted in ray diagram are _______________. A. Parallel B. Perpendicular C. Antiparallel 24. Light enters from air into diamond which has a refractive index of 2.4. Calculate the speed of light in diamond. The speed of light in air is 3 x 108 m/s. A. 1.239 x m/s B. 7.26 x 108 m/s C. 4.5 x 108 m/s 25. Where will they be image formed by a convex lens, when an object is placed the focus of lens? A. Beyond 2F B. At 2F C. At focus D. At Infinity 26. The focal lengths of four convex lenses P, Q, R and S are 20 cm, 15 cm, 5 cm and 10cm respectively. The lens having greatest power is : A. P B. Q C. R D. S 27. The path along which light travels is called ____________ A. ray of speed B. ray of light C. ray of particles D. wave velocity 28. When the object is placed within the focus convex lens, the image formed is : A. Real and erect B. Virtual and inverted C. Virtual and erect D. Real and inverted 29. Name the phenomena on which the working of lens is based. A. Reflection of air B. Refraction of air C. Reflection of light D. Refraction of light 30. A convex lens produces an inverted image magnified three times of an object placed at a distance of 15 cm from it. Calculate focal length of the lens. A. 9 cm B. 22 cm C. 11.25 cm ********** Refraction 1.A ray of white light is incident on a glass prism. Which ray diagram shows the ray as it passes through the prism and emerges from the opposite side? Ans: C 2. The optical phenomena, twinkling of stars, is due to A. Atmospheric reflection B. Total reflection C Atmospheric refraction D. Total refraction Ans: C 3. In optics an object which has higher refractive index is called a. Optically rarer b. Optically denser c. Optical density d. Refractive index Ans: B 4. Four students A, B, C and D traced the paths of incident ray and the emergent ray by fixing pins P and Q for incident ray and pins R and S for emergent ray for a ray of light passing through a glass slab. The correct emergent ray was traced by the student: (A) A (B) B (C) C (D) D Ans: B 5. A ray of light enters air from water and experiences refraction, then (A) i = r (B) i < r (C) i > r (D) i / r = 0 . Ans: B 6. The path of a ray of light passing through a rectangular glass slab was traced and angles measured. Which one out of the following is the correct representation of an angle of incidence (i), angle of refraction (r) and angle of emergence (e) as shown in the diagrams: (A) I (B) II (C) III (D) IV Ans: D 7. A student performs the experiment on tracing the path of a ray of light passing through a rectangular glass slab for different angles of incidence. He measures the angle of incidence i, angle of refraction r and angle of emergence e for all his observations. He would find that in all cases (A) i is more than r but (nearly) equal to e (B) i is less than r but (nearly) equal to e (C) i is more than e but (nearly) equal to r (D) i is less than e but (nearly) equal to r Ans :A 8. The diagram shows a ray of light incident on the edge of a piece of glass. The angle i is greater than the critical angle. Which arrow shows the direction of the ray after it leaves the edge of the glass? Ans: D 9. The diagram shows a ray of monochromatic light passing through a semi-circular glass block. What is the refractive index of the glass? A 0.64 B 0.77 C 1.31 D 1.56 Ans: D 10. The critical angle for glass-air interface is A. 240 D450 B.480 C.420 Ans: C 11.A totally reflecting equilateral prism can be used to deviate a ray of light through: A 30o B.60o C.75o 90o D Ans: B 12. The speed of light in glass is 2x105 km/s. What is the refractive index of glass? A. 1.5 B. 1 C.2 D.2.5 Ans: A 13. When a ray of light enters from denser medium to rare medium it bends A. towards normal B. away from normal C. perpendicular to normal D. parallel to normal Ans: B 14. The entire light is reflected into the denser medium, which is called total A. internal reflection of light B. external reflection of light C. internal refraction of light D. external refraction of light Ans: A 15.A totally reflecting right angled isosceles prism can be used to deviate a ray of light through : A 30o B.60o C.75o D.90o Ans: D 16.A small air bubble in a glass block when seen from above appears to be raised because of A, Refraction of light B. Reflection of light C. Reflection and Refraction of light D. None of above Ans :A 17.An object in a denser medium when viewed from a rarer medium appears to be raised .The shift is maximum for A, Red light B. Violet Light C. Yellow Light D.. Green Light Ans: B 18.What is the angle of incidence on the first face of the prism if a ray of light is incident normally on one face of an equilateral prism. A 0o B 60o C.90 0 D. None of the above Ans A 19. What is the angle of refraction from the first face of the prism if a ray of light is incident normally on one face of an equilateral prism. A 0o Ans A B 60o C.90 0 D. None of the above 20. What is the angle of incidence at the second face of the prism if a ray of light is incident normally on one face of an equilateral prism. A 0o B 60o C.90 0 D. None of the above Ans:B 21.Which of the following quantity does not change on refraction? A. Frequency B. Velocity C. Wavelength D. .None of the above Ans: Frequency 22.What will be the angle of refraction if a ray of light is incident normally on a plane glass slab? A.0o B.90o C.45o D. None of the above Ans: A 23. What will be the angle of deviation if a ray of light is incident normally on a plane glass slab? A.0o B.90o C.45o D. None of the above Ans: A 24. How does refractive index of a medium depend on its temperature. A. Refractive index decreases with increase in temperature of the medium B. Refractive index increases with increase in temperature of the medium C. Refractive index decreases with decrease in temperature of the medium D. None of the above Ans: A 25. How does refractive index of a medium depend on the wavelength of light used? A. Refractive index of a medium decreases with increase in wavelength of light. B. Refractive index of a medium decreases with decrease in wavelength of light. C. Refractive index of a medium increases with increase in wavelength of light. D. None of the above Ans: A 26. The highest refractive index is of: A. Glass B. Water C. Diamond D. Ruby Ans: C 27. State the approximate value of the critical angle for water-air surface A.42o B.49o C.70o D.20o Ans: B 28. Total internal reflection occurs only when a ray of light passes from a ..medium to a .medium A. Denser, Rarer B. Rarer, Rarer C, Denser, Denser E. Rarer, Denser Ans: A 29. Critical angle is the angle of .in denser medium A. Incidence B. Refraction C. Reflection D. None of the above Ans: A 30. The apparent depth of an object lying in a denser medium is always its real depth when viewed from any direction in the rarer medium. A. Less than B. Greater than C. Equal to D. None of the above Ans: A REFRACTION 1) A ray of light is incident normally on a pair of media then angle of incidence is degrees a) Zero ( b) 90 (c) 60 Ans: A 2) Choose the correct statements a) During refraction there is no reflection of light. b) During refraction partial reflection takes place. c) There is no change in speed of light with change in media. Ans: B 3) Name the phenomenon responsible for twinkling of stars a) Reflection b) refraction c) total internal reflection. Ans: B 4) During refraction the physical quantity which is fundamental is a) Wavelength. b) Speed. C) Frequency d) Amplitude. Ans: C 5) Light ray travels from denser to rarer medium then a) Wavelength increases b) wavelength decreases. C) remains same. Ans: B 6) Refractive index is ----proportional to a) Directly proportional to wavelength b) Inversely proportional to wavelength. c) Directly proportional to temperature Ans: B 7) Speed of light is same in two mediums then ray of light a) Passes without deviation b) Ray of light suffers deviation c) Refractive indices r same d) Refractive index in first medium is more than second. Ans: A 8) Speed of light ----with temperature and refractive index ----with temperature a) Increases. , increases b) Decreases. , increases c) Increases. , decreases. Ans: C 9) Lateral displacement is inversely proportional to a) Thickness of medium b) Refractive index c) Wavelength. Ans: A 10) A ray of light is incident on a glass slab then relation between angle of incidence and angle of emergence is (select the incorrect statement) a) Both are directly proportional b) Both are inversely proportional c) Both are equal Ans: B 11) A ray of light from liquid to glass pass straight with out bending if a) Incidence angle is zero b) Refractive indices for a pair of media is different c) Refractive index of liquid and glass is same I) a. ii) A and c. iii) B and c Ans: ii 12) A ray of light while passing from medium A to medium B speeds up because refractive index of A) A is more than B b) B is more than A c) Wavelength of B is more than wavelength of A d) Refractive index of B is smaller than A. i) A. ii) b, d. iii) c, d. iv) a, d. Ans: A 13) Speed of all colours of light in air or vaccum is a) Different, (b) same. C. Depends upon temperature. Ans: A 14) A prism has ----- plane surfaces. a) 1. b) 2. C) 5. D.3 Ans: C 15) In a prism refraction of light takes place at two inclined faces so a) Emergent ray is parallel to incident ray. b) Emergent ray is not parallel to incident ray c) Emergent ray bends towards the normal. Ans: B Refraction through lens 1. The first and second focal lengths are equal i.e. f1 = f2 (numerically) when (a) When the lens is placed on the surface of water (b) When the lens is placed on the surface of oil (c) When the lens is placed inside water (d) None of the above Ans: c. when the lens is placed inside water. Reason: when the medium on both the sides of a lens is same, its first and second focal lengths are equal. 2. Which of the following lens has virtual focus? (a) Short focal length lens(b) Long focal length lens (b) Bi-convex lens (d) Bi-concave lens Ans: d. Bi-concave lens 3. A convex lens is known as Equi-convex lens when (a) The Optical centre is in the middle of the line joining C1 and C2 (b) The Optical centre of the lens is closer to C1 (c) The Optical centre of the lens is closer to C2 (d) The optical centre of the lens coincides with C1 Ans: a. The Optical centre is in the middle of the line joining C1 and C2 4. A double convex lens of glass has a focal length of 10cm in air. When immersed in water, the focal length will be: (a) 7.5 cm (b) 10.0 cm (c) 9.8 cm (d) 40 cm Ans: d. 40cm Reason: when a lens is placed in water, instead of air its focal length Increases. 5. The focal length of a thick convex lens is _______ that of a thin convex lens. (a) More than (b) less than (c) equal to (d) double of Ans: b. less than 6. An object is placed at the focus of a concave lens. Where will be the image? (a) At infinity (b) Away from 2F (c) Between 2F and F (d) Between F and O Ans: d. between F and O 7. A convex lens forms (a) Only real images (b) only virtual images (c) Both real and virtual images (d) only magnified images Ans: b. both real and virtual images 8. A concave lens forms (a) Only real images (b) only virtual images (c) both real and virtual images (d) only magnified images Ans: b. only virtual images. 9. The magnification of ____________ lens is always less than 1. (a) Short focal length lens(b) Long focal length lens (b) Bi-convex lens (d) Bi-concave lens Ans: d. Bi-concave lens 10. A beam of parallel light rays incident obliquely converges at ____________ after refraction through a convex lens. (a) At the second focal length (b) at some point on the second focal plane (c) at some point on the principal axis (d) At some point on the first focal plane Ans: b. at some point on the second focal plane. 11. A light ray passes through _________of a convex lens emerges parallel to the principal axis after refraction. (a) F1 (b) F2 (c) C1 (d) C2 Ans: a. F1 12. A real, inverted and highly diminished image is formed when the object is placed (a) At the first focal point of a convex lens (b) At the second focal point of a convex lens (c) At a point which is very far from a convex lens (d) At the first focal length of a concave lens Ans: c. At a point which is very far from a convex lens 13. A virtual, erect and highly diminished image is formed when the object is placed (a) At the first focal point of a convex lens (b) At the second focal point of a convex lens (c) At the first focal point of a concave lens (d) At the second focal length of a concave lens Ans: d. at the second focal length of a concave lens 14. When the object moves from a large distance towards a concave lens, the image shifts from focus towards the ____________. (a) Optical centre (b) Centre of curvature C1 (c) Centre of curvature C2 (d) Infinity Ans: a. optical centre 15. When the object moves from a large distance towards a concave lens, the size of the image (a) Increases (b) decreases (c) Remains the same (d) may increase or decrease Ans: a. increases 16. When the object moves from a large distance towards a convex lens, the size of the image (a) Increases (b) decreases (c) Remains the same (d) may increase or decrease Ans: a. increases 17. The image produced by a ________ lens is always diminished. (a) Diverging lens (b) converging lens (c) thin lens (d) thick lens Ans: Diverging lens 18. How is the power of a lens related to its focal length? (a) Power increases with the increase in the focal length (b) Power increases with the decrease in the focal length (c) Power remains the same when the focal length changes (d) Power increases or decreases with the increase in the focal length. Ans: b. Power increases with the decrease in the focal length 19. Lens formula for a concave lens is 1 1 1 1 1 1 1 1 1 1 1 1 (a) + = (b) + = (c) - = (d) + = Ans: b. 1 + 1 = 1 20. If a lens deviates the ray towards its centre, the power is __________. (a) Positive (b) Negative (c) infinity (d) zero Ans: a. Positive 21. If a lens deviates a ray away from its centre, the power is ________. (a) Positive (b) Negative (c) infinity (d) zero Ans: b. Negative 22. Look at the diagram given below and answer: The magnification of the given lens is _____________. (a) +2.0 (b)-2.0 (c) +0.5 (d)-0.5 Ans: b. -2.0 23. Look at the diagram given below and answer. The power of the given lens is P Q S (a) Positive (b) negative (c) zero (d) infinity R Ans: Positive 24. Look at the diagram given below and answer. The power of the given lens combination is ___________. (Focal length of both the lenses = 50cm) (a) +4.0D (b) -4.0D (c) 0 (d) -2.0 D Ans: c. 0 Reason: The power of convex lens is +2 D and the power of concave lens is -2D. So, the power of combination is +2-2 = 0. 25. Look at the diagram given below and answer. The nature of the combination is ___________. (Focal length of both the lenses = 50cm) (a) Convex lens (b) concave lens (c) glass plate (d) plane mirror Ans: c. glass plate. Reason: since the power of this lens combination is zero, it behaves like a glass plate. 26. Look at the diagram given below and answer. Here, the magnification of the lens is ___________. L P Q (a) +2.5 (b) -2.5(c) +5.0 (d) -5.0 Ans: a. +2.5. 27. Human eye is a ____________ lens. R S (a) Convex lens (c) Plano convex lens Ans: a. convex lens. (b) concave lens (d) Plano concave lens 28. A person suffering from long sightedness or Hypermetropia wears spectacles having _________. (a) Convex lens (b) concave lens (c) plane mirror (d)glass plate Ans: a. convex lens. 29. A person suffering from short sightedness or myopia wears spectacles having _________. (b) Convex lens (b) concave lens (c) plane mirror (d)glass plate Ans: a. concave lens. 30. If the image formed by a lens is magnified, virtual and erect, the lens is a __________. (a) Concave lens (b) convex lens (c) Either convex or concave (d) neither convex nor concave Ans: b. convex lens. Refraction through a lens 1. Light from the Sun falling on a convex lens will converge at a Point called (a) centre of curvature (b) focus (c) radius of curvature (d) optical centre Answer: b 2. A divergent lens will produce (a) always real and magnified image (b) always virtual and magnified image (c) always real and diminished image (d) always virtual and diminished image Answer: d 3. When object moves closer to convex lens, the image formed by it shift (a) away from the lens (b) towards the lens (c) first towards and then away from the lens (d) first away and then towards the lens Answer: a 4. A magnified virtual image is formed by a convex lens when the object is at (a) F (b) between F and 2F (c) 2F (d) between F and O Answer: d 5. Which of the following statements is true? (a) A convex lens has 4 diopter power having a focal length 0.25 m (b) A convex lens has -4 diopter power having a focal length 0.25 m (c) A concave lens has 4 diopter power having a focal length -0.25 m (d) A concave lens has 4 diopter having a focal 0.25 m Answer: a 6. Magnifying power of a concave lens is (a) always > 1 (b) always < 1 (c) always = 1 (d) can have any value Answer: b 7. The image formed by a convex lens can be (a) virtual and magnified (b) virtual and diminished (c) virtual and of same size (d) virtual image is not formed Answer: a 8. If the power of a lens is 2 D, what is its focal length? (a) +50 cm (b) -100 cm (c) -50 cm (d) +100 cm Answer: c 9. If the magnification produced by a lens has a negative value, the image will be (a) virtual and inverted (b) virtual and erect (c) real and erect (d) real and inverted Answer: d 10. For the above diagram the image formed is (a) at F2 (b) at 2F2 (c) beyond 2F2 (d) between O and F2 Answer: c 11. Choose the diagram depicting the correct path of a light ray for the below figure (a) b) Answer: a 12. From the given diagram answer the following questions c) (i) The focal length of the given convex lens is (a) 30 cm (b) -20 cm (c) 20 cm (d) -30 cm Answer: c (ii) The object distance is (a) 30 cm (b) -20 cm (c) 20 cm (d) -30 cm Answer: d (iii) The nature of the image formed is (a) Virtual and inverted (b) virtual and erect (c) real and erect (d) real and inverted Answer: d (iv) The image distance is (a) 60 cm (b) -60 cm (c) 50 cm (d) -50 cm Answer: a 16. Which of the following lenses would you prefer to use while reading small letters found in a dictionary? (a) A convex lens of focal length 50 cm (b) A concave lens of focal length 50 cm (c) A convex lens of focal length 5 cm (d) A concave lens of focal length 5 cm Answer: c 17. An object is placed at a distance of 8cm in front of a converging lens of focal length 10 cm. Find (i) the position of image (ii) Magnification (iii) Nature of the image (i) The position of image (a) 40 cm (b) -40 cm (c) 50 cm (d) -50 cm Answer: b (ii) Magnification (a) 0.5 (b) 5 (c) -5 (d) -0.5 Answer: b (iii) The nature of the image formed is (a) Virtual and inverted (b) virtual and erect (c) real and erect (d) real and inverted Answer: b 20. If the magnification produced by a lens has a negative value, the image will be (a) Virtual and inverted (b) virtual and erect (c) real and erect (d) real and inverted Answer: c Multiple choice questions Physics for ICSE Class 10 Topic: Spectrum 1) Which of the colours of the spectrum of white light undergoes maximum deviation when passed through a glass prism? a) b) c) d) Red because the wavelength is maximum. Violet because of the least wavelength. Red because it has least velocity. Violet because it has maximum velocity. Ans: b: Violet because of the least wavelength. 2) Angle of deviation of a monochromatic ray of light does not depend on a) b) c) d) Angle of incidence at the first surface. Angle of incidence at the second surface. Angle of the prism. The refractive index of the material of the prism. Ans: b: Angle of incidence at the second surface. 3) Name the objective property of a given colour when it undergoes refraction. a) b) c) d) Wavelength. Refractive index. Frequency. Velocity. Ans: c: Frequency. 4) The wavelength range of the electromagnetic radiation, by which vision is rendered possible is a) b) c) d) 400 - 800 450 - 750 4000 8000 4000 - 8000 nm Ans: c: 4000 8000 5) One of the common properties of electromagnetic radiations are a) b) c) d) All of None All of All of them are deflected by electric and magnetic field. of them are deflected by electric and magnetic fields. them are deflected by electric fields and not by magnetic fields. them are deflected by magnetic fields and not by electric fields. Ans: b None of them are deflected by electric and magnetic fields 6) When a ray of white light falls on the side of a glass prism, it suffers dispersion, a) b) c) d) At the first surface. After entering the prism. At the second surface, inside the prism. On leaving the second surface. Ans : a: At the first surface. 7) What is the frequency of a ray of light which has a wavelength 4000 in vacuum? a) b) c) d) 7.5 7.5 1.3 1.3 X X X X 1014 1014 1014 1014 Hz Hz Hz Hz Ans: a: 7.5 X 1014 Hz 8) What is the cause of dispersion of white light when passed through a prism? a) b) c) d) Different Different Different Different deviation of the colours. frequencies of colours. speed of colours in a medium. speeds of colours in vacuum. Ans: c: Different speed of colours in a medium. 9) Name electromagnetic radiation that can pass through a quartz prism a) b) c) d) Visible light. Gamma rays. UV rays. Infra red rays. Ans: c: UV rays. 10)The critical angle of all the colours of white light, at a glass-air interface is a) b) c) d) 45o 42o 60o Different values for each colour. Ans: b: 42o 11)The correct sequence of colours from top to bottom in the figure given below is a) b) c) d) VIBGYOR ROYGBIV No particular order White light Ans: b: ROYGBIV 12) The electromagnetic radiation used for detecting the purity of ghee is a) b) c) d) Visible light X rays Infra red rays Ultraviolet Ans: d: Ultraviolet 13) Which among the following is an application of Infra red rays a) b) c) d) To produce vitamin D in plants In a radar For studying the atomic arrangement of crystals As signals during wars. Ans: d: As signals during wars. 14) The electromagnetic radiation which doesn t not affect a photographic plate is a) b) c) d) UV rays X rays IR rays Gamma rays Ans: c : IR rays 15) The method of detection of an electromagnetic radiation of wavelength less than 0.01 nm is a) b) c) d) It can cause fluorescence in some materials. Silver chloride solution turns dark brown when exposed to it. A photographic plate is affected. Can penetrate a thick iron sheet. Ans: d: Can penetrate a thick iron sheet. 16) X rays are generated by a) b) c) d) an electric circuit Heating an object to a very high temperature Slowing down high energy electrons by colliding with an object Nuclear fission Ans: c : Slowing down high energy electrons by colliding with an object 17) The production of an electromagnetic wave by an oscillating charge was predicted by a) b) c) d) Hertz Maxwell Marconi JC Bose Ans: a: Hertz 18) Speed of gamma ray, x-rays and microwaves in free space are vg , vx and vm respectively, then the correct option a)vg> vx>vm b) vg= Vx= v c) vg< Vx< Vm d) vg> Vx> Vm Ans: b: vg= Vx= v 19) Ozone layer absorbs a) b) c) d) Visible radiations Infrared radiations Ultraviolet radiation All electromagnetic waves, to the same extent Ans: c: Ultraviolet radiation 20) Green house effect is mainly due to a) b) c) d) Visible radiation Ultraviolet radiation Infrared radiation X rays Ans: c: Infrared radiation 21) A short ray of white light is incident from air to a glass slab at an angle of 90 . After traversing through the glass slab, the first color that is bound to emerge is a) b) c) d) Blue Green Violet Red Ans: d: Red 22) If a glass prism is dipped in water, the dispersive power will a) b) c) d) Increase Remain unchanged Decrease May increase or decrease Ans: c : Decrease 23) A narrow beam of white light goes through a slab having parallel faces, then a) The light [white] never splits into different colours. b) The emergent beam will be a spectrum c) The light inside the slab splits into different colours and reunites to form the white beam d) The light inside the slab remains white Ans: c : The light inside the slab splits into different colours and reunites to form the white beam 24) A prism can produce a minimum deviation delta in a light beam. If three such prisms are combined, the minimum deviation that can be produced is a) b) c) d) 0 Delta 2 3 Ans: b: Delta 25) A ray of white light is passed through a hollow prism, then the phenomenon observed is a) b) c) d) Dispersion Angular deviation Lateral displacement Total internal reflection Ans: c: Lateral displacement 26) The angle of deviation produced in the path of colours when passed through a prism a) b) c) d) Increases from red to violet Decreases from red to violet Angle of deviation will be the same for all colours. None of the above. Ans: a: Increases from red to violet 27) The type of prism used for the study of infrared rays a) b) c) d) Glass prism Crystal prism Quartz prism Rock salt prism Ans: d: Rock salt prism 28) Refractive index of glass is a) b) c) d) Greatest for violet colour Least for violet colour Greatest for red colour Refractive index remains the same for all colours. Ans: a: Greatest for violet colour 29) The formation of rainbows is an example of a) b) c) d) Interference of light Diffraction of light Dispersion of light Polarization of light Ans: c: Dispersion of light 30) Name the phenomenon observed in the path of a LASER light, when passed through a prism a) b) c) d) Refraction Total internal reflection Dispersion Reflection Ans: a: Refraction 1. The refractive index of glass, when a ray of light travels from air to glass is 1.5. Calculate the refractive index when light travels from glass to air. (a) 0.67 (b) 0.38 (c) 0.50 (d) 0.69 2. The ratio between the sines of angle of incidence in water to the sine of angle of incidence in air is 0.75. Calculate a w. (a) [1.33] (b) 1.38 (c) 2.25 (d)1.31 3. The refractive index of a material is 1.33. If the velocity of light in vacuum is 3 10 ms , find the velocity of light in the material. (a) 2.25 10 ms . (b) 2.25 10 ms . (c) 3.25 10 ms (d) 3.50 10 ms 4. The velocity of light in air is 3 10 ms and in glass is 2 10 ms , Find the refractive index of glass. (a) 1.5 (b) 2.5 c) 1.25 d) 2.25 5. The velocity of light in air is 3 10 ms . Calculate the velocity of light in diamond of refractive index 2.5. (a) 1.2 10 ms (b) 1 10 ms (c) 2.2 10 ms (d) 2.5 10 ms 6. A glass block 3.0 cm thick is placed over a stamp. Calculate the height through which the image of the stamp is raised. Refractive index of glass is 1.54. (a) 1.06 cm (b) 1.30 cm (c) 1.54 cm (d) 1.36 cm 7. A coin is placed at a depth of 15 cm in a beaker containing water. The refractive index of water is 4/3, calculate height through which the image of the coin is raised. (a) 3.75 cm (b) 3.25 cm (c) 3.06 cm (d) 3.50 cm 8. The floor of a water tank appears at a depth of 2.5 m. If the refractive index of water is 1.33, find the actual depth of water. (a) 3.325 m (b) 2.235 m (c) 3.235 m (d) 2.325 m 9. A postage stamp placed under a glass, appears raised by 8mm. If refractive index of glass is 1.5, calculate the actual thickness of the glass slab. (a) 24 mm (b) 12 mm (c) 16 mm (d) 28 mm 10. A stone placed at the bottom of a water tank appears raised by 80 cm. If the refractive index of water is 4/3, find the actual depth of water in the tank. (a) 320 cm (b) 380 cm (c) 240 cm (d) 220 cm 11. An object is placed at a distance of X from a convex lens, when a real image is formed at a distance of 15 cm from the lens. If the focal length of the lens is 10 cm, calculate (a) value of X (b) the magnification produced. State the characteristics of the image. (a) -30 cm, 0.5 and the image is real, inverted and diminished (b) -20 cm; 0.2 and the image is real, inverted and enlarged (c) -30 cm; 0.8 and the image is real, erect and diminished (d) -20 cm; 0.5 and the image is virtual, inverted and diminished 12. A convex lens of focal length 10 cm is placed at a distance of 60 cm from a screen. How far from the lens should be placed an object so as to obtain a real image on the screen? Calculate the magnification of the image and its characteristics. (a) u = -12 cm ; m = 5; Real, inverted and enlarged (b) u = -10 cm ; m = 6; virtual, erect and diminished (c) u = -12 cm ; m = 5; real, inverted and enlarged (d) u = -10 cm ; m = 6; virtual, inverted and diminished 13. An object of height 3 cm is placed at a distance of 24 cm from a convex lens of focal length 10 cm, when an image is formed on the screen on the other side of the lens. Calculate (a) the distance of the screen from the lens (b) The size of image (c) the characteristics of image. (a) 17.14 cm; 2.14 cm; Real, inverted and diminished (b) 16.14 cm; 3.14 cm; Real, inverted and enlarged (c) 16.30 cm; 1.14 cm; virtual, inverted and diminished (d) 17.14 cm; 2.14 cm; Real, erect and diminished 14. A convex lens produces a real and inverted image 2.5 times magnified at a distance of 25 cm from the lens. Calculate focal length of the lens (a) 7.14 cm (b) 14.7 cm (c) 2.14 cm (d) 17.14 cm 15. An object when placed in front of a convex lens forms a real image of 0.5 magnification. If the distance of the image from the lens is 24 cm, calculate focal length of the lens. (a) 8 cm (b) 6 cm (c) 9 cm (d) 7 cm 16. A convex lens forms a real image 4 times magnified when placed at a distance of 6 cm from the lens. Calculate the focal length of the lens. (a) 4.8cm (b) 3.8 cm (c) 4.3 cm (d) 3.3 cm 17. An object of height 2 cm is placed at a distance of 8 cm from a convex lens of focal length 10 cm. Calculate (a) position of the image (b) the size of the image. State the characteristics of the image. (a) -40 cm; 10 cm ; the image is virtual, erect and enlarged (b) -20 cm; 10 cm ; the image is virtual, inverted and enlarged (c) -20 cm; 10 cm ; the image is real, erect and enlarged (d) -40 cm; 10 cm ; the image is real, erect and diminished 18. An object 1.4 cm high when placed in front of a convex lens at a distance of 6 cm, forms a virtual image at a distance of 24 cm from the lens. Calculate (a) the focal length of the lens (b) the size of the image. (a) 8 cm ; 5.6 cm (b) 7 cm ; 3.6 cm (c) 6 cm ; 4.6 cm (d) 5 cm ; 5.6 cm 19. A convex lens forms a 2.5 times magnified virtual image when an object is placed at a distance of 8 cm from the lens. Calculate (a) the distance of the image from the lens (b) the focal length of lens. (a) 20cm; 13.3cm (b) 20 cm; 12.5cm (c) 10cm ; 13.3cm (d) 10cm ; 12.3cm 20. An object 1 cm high is placed at a distance of 4 cm from a convex lens of focal length 6 cm. Calculate (a) the position of the image (b) size of a image. State the characteristics of the image (a) 12 cm ; 3 cm (b) 10 cm ; 5 cm (c) 12 cm ; 6 cm (d) 10 cm ; 3 cm 21. An object 4 cm high is placed at a distance of 40 cm from the optical centre of a concave lens of focal length 20 cm. Calculate (a) the position of the image (b) the size of the image, Also state the characteristics of the image. (a) -13.33 cm ; 1.33 cm ; the image is virtual, erect and diminished. (b) -12.33 cm ; 2.33 cm ; the image is virtual, erect and enlarged (c) -13.33 cm ; 1.33 cm ; the image is real, erect and diminished (d) -12.33 cm ; 2.33 cm ; the image is virtual, erect and diminished 22. An object 2 cm high is placed at a distance of 25 cm from the optical centre of a concave lens of focal length 15 cm. Calculate (a) the position of the image (b) the size of the image. (a) -9.37 cm ; 0.75 cm (b) -6.38 cm ; 0.25 cm (c) -8.37 cm ; 0.65 cm (d) -7.37=8 cm ; 0.25 cm 23. A concave lens forms 4 times diminished and virtual image when an object is placed at a distance of 80 cm. calculate (a) the position of the image (b) the focal length of the lens. (a) 20 cm ; -26.67 cm (b) 15 cm ; -28.62 cm (c) 10 cm ; -20.67 cm (d) 18 cm ; -28.62 cm 24. A concave lens has focal length 15 cm. At what distance should the object from the lens be placed, so as to form an image at 10 cm from the lens. Also find magnification of the lens. (a) -30 cm ; 0.33 (b) 20 cm ; 0.33 (c) 30 cm ; -0.33 (d) -20 cm ; 0.33 25. Calculate the power of a convex lens of focal length 12.5 cm (a) +8D (b) +5D (c) +6D (d) +7 26. A converging lens has a focal length 40 cm. Calculate its power. (a) +2.5 D (b) +7D (c) +3.5D (d) 5D 27. A lens which forms a real image has a focal length 8 cm. Calculate its power. (a) +12.5 D (b) +14.5D (c) +15D (d) 13.5D 28. An eye specialist prescribes a number +4.5 D to a person for his glasses. What is the nature of the lens? What is the focal length of the lens? (a) +22.22 cm (b) +12.22 cm (c) +22.12 cm (d) +23.22 cm 29. State the nature of the lens and the focal length of its power is +4D. (a) convex ; 25 cm (b) concave ; 25 cm (c) convex ; 23 cm (d) concave ; 23 cm 30. The number of the glasses of a person is +0.75 D. What is the nature of the lens and what is its focal length? (a) convex ; 133.33 cm (b) concave ; 133.33 cm (c) convex ; 132.32 cm (d) concave ; 132.32 cm 31. The focal length of the glasses of a short sighted person is 37.5 cm. Calculate the power of the glasses and their nature. (a) -2.67 D, minus sign indicates that the lens is concave in nature (b) -2.67 D, minus sign indicates that the lens is convex in nature 32. The focal length of a concave lens is 10 cm. Calculate its power. (a) -10 D (b) 10 D (c) -20 D (d) 20 D 33. The focal length of the lens of a myopic person is 40 cm. What is the power of the lens? (a) -2.5 D (b) 2.5 D (c) 3.5 D (d) -3.5 D 34. The power of the lens of a myopic person is -3.75 D. Calculate the focal length of the lens. (a) -26.67 cm (b) -36.36 cm (c) 26.67 cm (d) 36.36cm 35. Calculate the focal length of a lens of power -2.75 D. (a) -36.36 cm (b) 26.67 cm (c) -26.67 cm (d) 36.36 cm 36. The power of a concave lens is -12.5 D. What is the focal length of the lens? (a) -8 cm (b) 8 cm (c) -6 cm (d) 6 cm SCIENCE PAPER I Maximum marks: 40 Time allowed: ONE HOUR (inclusive of reading time ALL THE QUESTIONS ARE COMPULSORY The intended marks for questions or parts of the questions are given in brackets [ ] Question 1: a) The phenomenon of return of light in the same medium after striking a surface [is called ____________________________. [1] 1. Reflection 2. Refraction 3. Diffraction 4. Polarization b) When a light passing from one rare medium to a denser medium then the velocity of light ________________. [1] 1. Increase 2. Decrease 3. No change 4. None of these. c) 1. 2. 3. 4. Which of the following not changes during refraction? Wavelength Velocity Frequency None of these. [1] d) The angle of reflection for perpendicularly incident ray 1. 00 2. 450 3. 1800 4. 900 e) In the following diagram shown below: [1] [1] 1. EF is the incident ray and GH is the refracted ray. 2. EF is the incident ray and OOI is the refracted ray. 3. GH is the incident ray and EF is the refracted ray. 4. OOI is the emergent ray and GH is the incident ray. f) The focal length of a lens depends on the [1] 1 The refractive index of the material of the prism 2. The radius of curvature of the two surfaces of lens 3. Both (a) and (b) 4. None of these g) The refractive index of medium B with respect to medium A is [1] h) The path of the [1] diagrams showing the correct ray after passing through the 1. II and III only 2. I and II only 3. I, II and III 4. I, II and IV i) From the following diagram, identify the characteristics of the image formed by concave lens: [1] object 1. 2. 3. 4. Real, diminished and inverted Virtual, diminished and erect Real enlarge and inverted Virtual, enlarged and erect. j) The frequency of ____ colour of light is maximum and ____ colour of light is minimum. [2] 1. Violet, red 2. Blue, red 3. Green, blue 4. Red, violet Question 2: a) A girl lifts a doll from the floor and places it on a table. If the weight of the doll is known, then ____ is required to calculate the work done by the girl on the doll .[1] 1. Time taken to lift the doll 2. Height of the table 3. Mass of the doll 4. Shape of the doll b) A body is acted upon by two unequal forces in the opposite direction, but not in the same line. The effect is [1] 1. The body will have only translational motion 2. The body will have rotational motion 3. Both 1 and 2 4. None of the above. c) The diagram shows a uniform meter rule: [4] i) The total anticlockwise moment about O 1.1500gf cm 2.4000gf cm 3.1900gf cm 4. 6000gf cm ii) The total clockwise moment about O is 1.2500 gf cm 2. 2000 gf cm 3. 5000 gf cm [1] 4. 4000 gf cm iii) The resultant moment of force is 1.1000 gf cm 2.2000 gf cm 3. 3000 gf cm 4.none of the above iv) The distance from O where 100gf weight should be placed is 1 20 cm from the right hand side of O 2.10 cm from the right hand side of O. 3. 20 cm from the left hand side of O 4. 10 cm from the left hand side of O. d) When the displacement along the opposite direction of the force. Then the work is said to be__________ [1] 1. 2. 3. 4. Zero Negative Positive Infinitive e) 1. 2. 3. 4. KWh is the unit of: Power Force Energy None of these [1] f) A block A, whose weight is 100N, is pulled up a slope of length 5m by means of a constant force F (=100N) as illustrated. [2] I) what is the work done by the force F in moving the block A, 5m along the slope? 1.500J 2.300J 3.200J 4.100J ii) What is the increase in potential energy of the block A? 1.500J 2.300J 3.200J 4.100J QUESTION 03: a) Single fixed pulley is used because it: [1] 1.. Has a mechanical advantage greater than 5 2. Has a velocity ratio less than 2 3. Gives 100% efficiency 4. Helps to apply the effort in a convenient direction b. A block and tackle system has 5 pulleys. If an effort of 1000 N is needed in the downward direction to raise a load of 4500 N, calculate the mechanical advantage, [1] A. 4.5 B. 5 C. 5.5 D. 5.8 c) 150 N raised by a system of 3 pulleys on the application of force 50N, what is the efficiency? [1] 1) 50 % 2. 75 % 3. 33.3 % 4. 100 % d) When we want to use a machine as a speed multiplier then 1. Effort > load 2. Effort < load 3. Effort = load 4. None of these [1] e) Identify the conditions required to hear a clear and distinct echo by humans in air [2] 1. The reflecting surface should be rough 2. The size of the reflecting surface should be smaller than the wavelength of sound. 3. The sound should not be reflected back within 0.1 s. 4. The incident should have the frequency more than 25000Hz. 5. The size of the reflecting surface should be larger than the wavelength of the sound. f) A person standing in front of a vertical cliff fires a gun and hears its echo in 3s. The speed of sound in air is 340ms-1. [4] cliff I) Calculate distance at which the person is standing in front of the cliff?Steps are given below to calculate the distance .Select the correct sequence of the steps from the given sequence: i)340 = 2d/3 ii) 340 = d/3 iii)d = 170 x 3 =510m iv) d = 340 x 3 = 1020m 1. ii) then iv. 2. iii) then iv. 3 .i) and IV. 4. i) and iii) 5. iii) then i) II)If the speed of the sound changes to 350m/s then how much distance should the person move towards or away from the cliff in order to hear the echo in the same time .Steps are given to calculate the distance .Select the correct sequence of the steps from the given option. i) 350 340 = 2d/3 ii) 340d + 350 = 2d/3 iii) d = 345 x 3 /2 = 517.5m iv) d = 30/2 = 15 m QUESTION 04: a) A ray of light passes through a right angled isosceles prism. i)what is the angle of deviation? 1.45 degrees 2.90 degrees [3] 3.180 degrees 4. Zero degrees ii) The instrument where this action of the prism is put to use 1. Binocular 2. Periscope 3 .camera 4. Telescope iii) Which prism surface behaves like a mirror? 1) AC 2) BC 3) AB 4) None of the above b) The most energetic electromagnetic radiations are : 1) Microwaves 2) ultraviolet waves 3) X rays [1] 4) gamma rays c) The radiation P is focused by a proper device on the bulb of a thermometer. Mercury in the thermometer shows a rapid rise. The radiation is [1] 1) Infrared radiation 2) Visible light 3) Ultraviolet radiation 4) X rays d) The phenomenon of splitting of white light into its constituent colours, on passing through a prism is called ____. [1] 1. Diffraction 2. Interference 3. Propagation 4. Dispersion e) Torque is depending on [1] 1. The magnitude of force applied (F) 2. The perpendicular distance of line of action of the force from the axis of rotation (d) 3. Pressure on the substance 4. Both (a) and (b) f) Two bodies of equal masses are placed at height h and 2h, find the ratio of potential energy. [1] 1. 1:2 2. 2:1 3. 2:3 4. 3:2 g) When a body falls its potential energy changes from U1 to U2. Find the relation between them 1. U1=U2 2. U1 3. U1>U2 4. None of these h) What is the relation among Mechanical advantage (MA), load (L) and effort (E)? A. MA = L x E B. MA x E = L C. E = MA x L D. none of these 37. The refractive index of glass, when a ray of light travels from air to glass is 1.5. Calculate the refractive index when light travels from glass to air. (a) 0.67 (b) 0.38 (c) 0.50 (d) 0.69 38. The ratio between the sines of angle of incidence in water to the sine of angle of incidence in air is 0.75. Calculate a w. (a) [1.33] (b) 1.38 (c) 2.25 (d)1.31 39. The refractive index of a material is 1.33. If the velocity of light in vacuum is 3 10 ms , find the velocity of light in the material. (a) 2.25 10 ms . (b) 2.25 10 ms . (c) 3.25 10 ms (d) 3.50 10 ms 40. The velocity of light in air is 3 10 ms and in glass is 2 10 ms , Find the refractive index of glass. (a) 1.5 (b) 2.5 c) 1.25 d) 2.25 41. The velocity of light in air is 3 10 ms . Calculate the velocity of light in diamond of refractive index 2.5. (a) 1.2 10 ms (b) 1 10 ms (c) 2.2 10 ms (d) 2.5 10 ms 42. A glass block 3.0 cm thick is placed over a stamp. Calculate the height through which the image of the stamp is raised. Refractive index of glass is 1.54. (a) 1.06 cm (b) 1.30 cm (c) 1.54 cm (d) 1.36 cm 43. A coin is placed at a depth of 15 cm in a beaker containing water. The refractive index of water is 4/3, calculate height through which the image of the coin is raised. (a) 3.75 cm (b) 3.25 cm (c) 3.06 cm (d) 3.50 cm 44. The floor of a water tank appears at a depth of 2.5 m. If the refractive index of water is 1.33, find the actual depth of water. (a) 3.325 m (b) 2.235 m (c) 3.235 m (d) 2.325 m 45. A postage stamp placed under a glass, appears raised by 8mm. If refractive index of glass is 1.5, calculate the actual thickness of the glass slab. (a) 24 mm (b) 12 mm (c) 16 mm (d) 28 mm 46. A stone placed at the bottom of a water tank appears raised by 80 cm. If the refractive index of water is 4/3, find the actual depth of water in the tank. (a) 320 cm (b) 380 cm (c) 240 cm (d) 220 cm 47. An object is placed at a distance of X from a convex lens, when a real image is formed at a distance of 15 cm from the lens. If the focal length of the lens is 10 cm, calculate (a) value of X (b) the magnification produced. State the characteristics of the image. (a) -30 cm, 0.5 and the image is real, inverted and diminished (b) -20 cm; 0.2 and the image is real, inverted and enlarged (c) -30 cm; 0.8 and the image is real, erect and diminished (d) -20 cm; 0.5 and the image is virtual, inverted and diminished 48. A convex lens of focal length 10 cm is placed at a distance of 60 cm from a screen. How far from the lens should be placed an object so as to obtain a real image on the screen? Calculate the magnification of the image and its characteristics. (a) u = -12 cm ; m = 5; Real, inverted and enlarged (b) u = -10 cm ; m = 6; virtual, erect and diminished (c) u = -12 cm ; m = 5; real, inverted and enlarged (d) u = -10 cm ; m = 6; virtual, inverted and diminished 49. An object of height 3 cm is placed at a distance of 24 cm from a convex lens of focal length 10 cm, when an image is formed on the screen on the other side of the lens. Calculate (a) the distance of the screen from the lens (b) the size of image (c) the characteristics of image. (e) 17.14 cm; 2.14 cm; Real, inverted and diminished (f) 16.14 cm; 3.14 cm; Real, inverted and enlarged (g) 16.30 cm; 1.14 cm; virtual, inverted and diminished (h) 17.14 cm; 2.14 cm; Real, erect and diminished 50. A convex lens produces a real and inverted image 2.5 times magnified at a distance of 25 cm from the lens. Calculate focal length of the lens (a) 7.14 cm (b) 14.7 cm (c) 2.14 cm (d) 17.14 cm 51. An object when placed in front of a convex lens forms a real image of 0.5 magnification. If the distance of the image from the lens is 24 cm, calculate focal length of the lens. (a) 8 cm (b) 6 cm (c) 9 cm (d) 7 cm 52. A convex lens forms a real image 4 times magnified when placed at a distance of 6 cm from the lens. Calculate the focal length of the lens. (a) 4.8cm (b) 3.8 cm (c) 4.3 cm (d) 3.3 cm 53. An object of height 2 cm is placed at a distance of 8 cm from a convex lens of focal length 10 cm. Calculate (a) position of the image (b) the size of the image. State the characteristics of the image. (a) -40 cm; 10 cm ; the image is virtual, erect and enlarged (b) -20 cm; 10 cm ; the image is virtual, inverted and enlarged (c) -20 cm; 10 cm ; the image is real, erect and enlarged (d) -40 cm; 10 cm ; the image is real, erect and diminished 54. An object 1.4 cm high when placed in front of a convex lens at a distance of 6 cm, forms a virtual image at a distance of 24 cm from the lens. Calculate (a) the focal length of the lens (b) the size of the image. (a) 8 cm ; 5.6 cm (b) 7 cm ; 3.6 cm (c) 6 cm ; 4.6 cm (d) 5 cm ; 5.6 cm 55. A convex lens forms a 2.5 times magnified virtual image when an object is placed at a distance of 8 cm from the lens. Calculate (a) the distance of the image from the lens (b) the focal length of lens. (a) 20cm ; 13.3cm (b) 20cm ; 12.5cm (c) 10cm ; 13.3cm (d) 10cm ; 12.3cm 56. An object 1 cm high is placed at a distance of 4 cm from a convex lens of focal length 6 cm. Calculate (a) the position of the image (b) size of a image. State the characteristics of the image (a) 12 cm ; 3 cm (b) 10 cm ; 5 cm (c) 12 cm ; 6 cm (d) 10 cm ; 3 cm 57. An object 4 cm high is placed at a distance of 40 cm from the optical centre of a concave lens of focal length 20 cm. Calculate (a) the position of the image (b) the size of the image, Also state the characteristics of the image. (e) -13.33 cm ; 1.33 cm ; the image is virtual, erect and diminished. (f) -12.33 cm ; 2.33 cm ; the image is virtual, erect and enlarged (g) -13.33 cm ; 1.33 cm ; the image is real, erect and diminished (h) -12.33 cm ; 2.33 cm ; the image is virtual, erect and diminished 58. An object 2 cm high is placed at a distance of 25 cm from the optical centre of a concave lens of focal length 15 cm. Calculate (a) the position of the image (b) the size of the image. (a) -9.37 cm ; 0.75 cm (b) -6.38 cm ; 0.25 cm (c) -8.37 cm ; 0.65 cm (d) -7.37=8 cm ; 0.25 cm 59. A concave lens forms 4 times diminished and virtual image when an object is placed at a distance of 80 cm. Calculate (a) the position of the image (b) the focal length of the lens. (a) 20 cm ; -26.67 cm (b) 15 cm ; -28.62 cm (c) 10 cm ; -20.67 cm (d) 18 cm ; -28.62 cm 60. A concave lens has focal length 15 cm. At what distance should the object from the lens be placed, so as to form an image at 10 cm from the lens. Also find magnification of the lens. (a) -30 cm ; 0.33 (b) 20 cm ; 0.33 (c) 30 cm ; -0.33 (d) -20 cm ; 0.33 61. Calculate the power of a convex lens of focal length 12.5 cm (a) +8D (b) +5D (c) +6D (d) +7D 62. A converging lens has a focal length 40 cm. Calculate its power. (a) +2.5 D (b) +7D (c) +3.5D (d) 5D 63. A lens which forms a real image has a focal length 8 cm. Calculate its power. (a) +12.5 D (b) +14.5D (c) +15D (d) 13.5D 64. An eye specialist prescribes a number +4.5 D to a person for his glasses. What is the nature of the lens? What is the focal length of the lens? (a) +22.22 cm (b) +12.22 cm (c) +22.12 cm (d) +23.22 cm 65. State the nature of the lens and the focal length of its power is +4D. (a) convex ; 25 cm (b) concave ; 25 cm (c) convex ; 23 cm (d) concave ; 23 cm 66. The number of the glasses of a person is +0.75 D. What is the nature of the lens and what is its focal length? (a) convex ; 133.33 cm (b) concave ; 133.33 cm (c) convex ; 132.32 cm (d) concave ; 132.32 cm 67. The focal length of the glasses of a short sighted person is 37.5 cm. Calculate the power of the glasses and their nature. (a) -2.67 D, minus sign indicates that the lens is concave in nature (b) -2.67 D, minus sign indicates that the lens is convex in nature 68. The focal length of a concave lens is 10 cm. Calculate its power. (a) -10 D (b) 10 D (c) -20 D (d) 20 D 69. The focal length of the lens of a myopic person is 40 cm. What is the power of the lens? (a) -2.5 D (b) 2.5 D (c) 3.5 D (d) -3.5 D 70. The power of the lens of a myopic person is -3.75 D. Calculate the focal length of the lens. (a) -26.67 cm (b) -36.36 cm (c) 26.67 cm (d) 36.36cm 71. Calculate the focal length of a lens of power -2.75 D. (a) -36.36 cm (b) 26.67 cm (c) -26.67 cm (d) 36.36 cm 72. The power of a concave lens is -12.5 D. What is the focal length of the lens? (a) -8 cm (b) 8 cm (c) -6 cm (d) 6 cm

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Additional Info : ICSE Class X Question Bank 2024 : Physics MCQs with Answers (Force, Work, Energy, Power, Machines, Refraction, Spectrum)
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