Grade X 10 Light : Reflection and Refraction Subject ...

1 [1] Grade X 10 Light : Reflection and Refraction Subject Science(Physics) 1. You are given three media A, B and C of refractive index , and The medium in which the Light will travel fastest is (a) A (b) B (c) C (d) equal in all three media 2. When white Light moves through vacuum : (a) Violet has greater speed than red (b) Red has greater speed than violet (c) All colours have the same speed (d) Different colours have different random speeds 3. A lens has a power of + It is: (a) A concave lens of local length 5 m (b) A convex lens of focal length 2 m (c) A convex lens of focal length 5 m (d) A concave lens of focal length 2 m 4. Morning sun is not so hot as the mid day sun because (a) Sun is cooler in the morning (b) Heat rays travel slowly is the morning (c) It is God gift (d) The sun s rays travel a longer distance through atmosphere in the morning 5. Where should an object be placed in front of a convex lens to get a real image of the size of the object?

2 (a) At the principal focus of the lens (b) At twice the focal length (c) At infinity (d) Between the optical centre of the lens and its principal focus. 6. An object is placed 60 cm in front of a concave mirror. The real image formed by the mirror is located 30 cm in front of the mirror. What is the object s magnification? (a) +2 (b) -2 (c) + (d) [2] 7. The image of an object placed in front of a convex mirror is formed at (a) the object itself (b) twice the distance of the object in front of the mirror (c) half the distance of the object in front of the mirror (d) behind the mirror 8. Light waves (a) Require air or another gas to travel through (b) Require an electric field to travel through (c) Require a magnetic field to travel through (d) Can travel through perfect vacuum 9. An object is placed cm in front of a convex mirror. The image appears 15 cm behind the mirror. What is the focal length of the mirror?

3 (a) +24 cm (b) +11 cm (c) -11 cm (d) -24 cm 10. Find the angle of incidence and angle of Reflection from the diagram. (a) 450, 400 (b) 550, 550 (c) 600, 600 (d) 300, 300 11. Velocity of Light in air is 3x108 m/s. While its velocity in a medium is m/s. Then, refractive index of this medium is (a) 3 (b) 5 (c) (d) 2 12. Focal length of a plane mirror is (a) zero (b) infinite (c) 25 cm (d) -25 13. An object is placed at a distance of 10 cm in front of a plane mirror, then the distance of image from mirror will be (a) 5 cm (b) 10 cm (c) 20 cm (d) 0 14. The radius of curvature of concave mirror is 12 cm. Then, the focal length will be [3] (a) 12 cm (b) 6 cm (c) -24 cm (d) -6 cm 15. A man is ft tall. What is the smallest size plane mirror he can use to see his entire image (a) ft (b) ft (c) 12 ft (d) 24 ft 16. A spherical mirror and a thin spherical lens have each a focal length of -15 cm.

4 The mirror and the lens are likely to be (a) both concave (b) both convex (c) the mirror is concave and the lens is convex. (d) the mirror is convex, but the lens is concave. 17. 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. 18. An object is situated at a distance of f/2 from a convex lens of focal length f . Distance of image will be (a) +(f/2) (b) +(f/3) (c) +(f/4) (d) -f 19. Two plane mirrors are set at right angle and a flower is placed in between the mirrors. The number of images of the flower which will be seen is (a) One (b) Two (c) Three (d) Four 20. An object is placed 20 cm from the concave mirror of focal length 10 cm, then image is formed at (a) behind the mirror (b) between the mirror and focus (c) at focus (d) centre of curvature of mirror 21.

5 The refractive index of dense flint glass is and for alcohol, it is with respect to air, then the refractive index of the lens flint glass with respect to alcohol is (a) (b) (c) (d) 22. A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature 36 cm. The distance of the object from the mirror is [4] (a) 20 cm (b) 10 cm (c) 12 cm (d) 5 cm 23. An object is placed at the centre of curvature of a concave mirror. The distance between its image and the pole is (a) equal to f (b) between f and 2f (c) equal to 2f (d) greater than 2f 24. A perfectly reflecting mirror has an area of 1 cm2. Light energy is allowed to fall on it for an hour at the rate of 10W cm-2. The force that acts on the mirror is (a) x 10-7 N (b) x 10-7 N (c) x 10-8 N (d) 10-8 N 25. Refractive index of diamond with respect to glass is If the absolute refractive index of glass is , then the absolute refractive index of diamond is (a) (b) (c) (d) 26.

6 A convex lens A of focal length 20 cm and a concave lens B of focal length 5 cm are kept along the same axis with a distance d between them. If a parallel beam of Light falling on A leaves B as a parallel beam, then the distance d in cm will be (a) 25 (b) 15 (c) 30 (d) 50 27. A thick plane convex lens made of crown glass (refractive index ) has thickness of 3 cm at its centre. An ink mark made at the centre of its plane face, when viewed normal through the curved face, appears to be a distance x from the curved face. Then, x is equal to (a) 2 cm (b) cm (c) cm (d) cm 28. If the refractive indices for water and diamond relative to air are and respectively, then the refractive index of diamond relative to water is- (a) (b) (c) (d) None of these 29. There is an equiconvex lens of focal length of 20cm. If the lens is cut into two equal parts perpendicular to the principle axis, the focal lengths of each part will be (a) 20 cm (b) 10 cm (c) 40 cm (d) 15 cm 30.

7 An object is placed in front of a screen and a convex lens is placed at a position such that the size of the image formed is 9 cm. When the lens is shifted through a [5] distance of 20 cm. the size of the image becomes 1 cm. The focal length of the lens and the size of the object are respectively. (a) cm and cm (b) cm and cm (c) 6 cm and 3 cm (d) cm and 3 cm 31. An object is placed 60 cm in front of a convex mirror. The virtual image formed by the mirror is located 30 cm behind the mirror. What is the object s Magnification (a) +2 (b) -2 (c) + (d) 32. Light rays A and B fall on optical component X and come out as C and D. The optical component is a (a) concave lens (b) convex lens (c) convex mirror (d) prism 33. An object is placed cm in front of a concave mirror whose focal length is cm. What is the magnification of the object? (a) + (b) (c) + (d) 34. An object is placed at the radius of curvature of a concave spherical mirror.

8 The image formed by the mirror is (a) located at the focal point of the mirror. (b) located between the focal point and the radius of curvature of the Mirror. (c) located at the center of curvature of the mirror. (d) located out beyond the center of curvature of the mirror. 35. An object is placed cm in front of a concave mirror whose focal length is cm. Where is the image located? (a) x 102 cm in front of the mirror (b) x 102 cm behind the mirror (c) x 101 cm in front of the mirror (d) x 101 cm behind the mirror 36. Which statement best describes the property of Light waves illustrated in the diagram below? [6] (a) some materials absorb Light waves. (b) Some materials are refracted by some materials. (c) Light waves are refracted by some materials. (d) Light waves are emitted by some materials. 37. Which of the following can make a parallel beam of Light when Light from a point source is incident on it?

9 (a) Concave mirror as well as convex lens (b) Convex mirror as well as concave lens (c) Two plane mirrors placed at 90 to each other (d) Concave mirror as well as concave lens 38. A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is (a) 30 cm (b) 20 cm (c) 40 cm (d) 60 cm 39. Under which of the following conditions a concave mirror can form an image larger than the actual object? (a) When the object is kept at a distance equal to its radius of curvature (b) When object is kept at a distance less than its focal length (c) When object is placed between the focus and centre of curvature (d) When object is kept at a distance greater than its radius of curvature 40. Which of the following statements is true? (a) A convex lens has 4 dioptre power having a focal length m (b) A convex lens has 4 dioptre power having a focal length m (c) A concave lens has 4 dioptre power having a focal length m (d) A concave lens has 4 dioptre power having a focal length m 41.

10 Magnification produced by a rear view mirror fitted in vehicles [7] (a) is less than one (b) is more than one (c) is equal to one (d) can be more than or less than one depending upon the position of the object in front of it 42. Rays from the Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object? (a) 15 cm in front of the mirror (b) 30 cm in front of the mirror (c) between 15 cm and 30 cm in front of the mirror (d) more than 30 cm in front of the mirror 43. In torches, search lights and headlights of vehicles the bulb is placed (a) between the pole and the focus of the reflector (b) very near to the focus of the reflector (c) between the focus and centre of curvature of the reflector (d) at the centre of curvature of the reflector 44. The laws of Reflection hold good for (a) plane mirror only (b) concave mirror only (c) convex mirror only (d) all mirrors irrespective of their shape 45.