Tiêu đề 28. Ray Optics Easy.pdf ✅

1. A T.V. tower has a height of 100 m. How much population is covered by T.V. broadcast, if the average population density around the tower is 1000/ km2 ? (a) 39.5 × 105 (b) 19.5 × 106 (c) 29.5 × 107 (d) 9 × 104 2. The given figure shows the waveforms for two inputs A and B and that for the output Y of a logic circuit. The logic circuit is – t O T1 T2 T3 T4 A t O T1 T2 T3 T4 B t O T1 T2 T3 T4 Y (a) An AND gate (b) An OR gate (c) A NAND gate (d) A NOT gate 3. Two vertical plane mirrors are inclined at an angle of 60 with each other. A ray of light travelling horizontally is reflected first from one mirror and then from the other. The resultant deviation is (a) 60 (b) 120 (c) 180 (d) 240 4. A plane mirror reflects a pencil of light to form a real image. Then the pencil of light incident on the mirror is (a) Parallel (b) Convergent (c) Divergent (d) None of the above 5. What should be the angle between two plane mirrors so that whatever be the angle of incidence, the incident ray and the reflected ray from the two mirrors be parallel to each other (a) 60 (b) 90 (c) 120 (d) 175 6. A plane mirror reflecting a ray of incident light is rotated through an angle  about an axis through the point of incidence in the plane of the mirror perpendicular to the plane of incidence, then (b) The reflected ray rotates through an angle  (c) The reflected ray rotates through an angle 2 (d) The incident ray is fixed 7. A plane mirror is approaching you at a speed of 10cm/ sec You can see your image in it. At what speed will your image approach you (a) 10cm/ sec (b) 5cm/ sec (c) 20cm/ sec (d) 15cm/ sec 8. A light bulb is placed between two plane mirrors inclined at an angle of 60 . The number of images formed are (a) 6 (b) 2 (c) 5 (d) 4 9. It is desired to photograph the image of an object placed at a distance of 3m from the plane mirror. The camera which is at a distance of 4.5m from the mirror should be focussed for a distance of (a) 3m (b) 4.5m (c) 6m (d) 7.5m 10. A thick plane mirror shows a number of images of the filament of an electric bulb. Of these, the brightest image is the (a) First (b) Second (c) Fourth (d) Last 11. A man is 180cm tall and his eyes are 10cm below the top of his head. In order to see his entire height right from toe to head, he uses a plane mirror kept at a distance of 1m from him. The minimum length of the plane mirror required is (a) 180cm (b) 90cm (c) 85cm (d) 170cm 12. A person is in a room whose ceiling and two adjacent walls are mirrors. How many images are formed (a) 5 (b) 6 (c) 7 (d) 8 13. When a plane mirror is placed horizontally on a level ground at a distance of 60m from the foot of a tower, the top of the tower and its image in the mirror subtend an angle of 90 at the eye. The height of the tower will be (a) 30m (b) 60m (c) 90m (d) 120m 14. A ray of light incidents on a plane mirror at an angle of 30 . The deviation produced in the ray is (a) 30 (b) 60 (c) 90 (d) 120 15. A ray of light is incidenting normally on a plane mirror. The angle of reflection will be (a) 0 (b) 90 (c) Will not be reflected (d) None of the above
16. When light wave suffers reflection at the interface from air to glass, the change in phase of the reflected wave is equal to (a) 0 (b) 2  (c)  (d) 2 17. A ray is reflected in turn by three plain mirrors mutually at right angles to each other. The angle between the incident and the reflected rays is (a) 90 (b) 60 (c) 180 (d) None of these 18. Two plane mirrors are at right angles to each other. A man stands between them and combs his hair with his right hand. In how many of the images will he be seen using his right hand (a) None (b) 1 (c) 2 (d) 3 19. When a plane mirror is rotated through an angle  then the reflected ray turns through the angle 2 then the size of the image (a) Is doubled (b) Is halved (c) Remains the same (d) Becomes infinite 20. A plane mirror produces a magnification of (a) −1 (b) +1 (c) Zero (d) Between 0 and +  21. A plane mirror makes an angle of 30 with horizontal. If a vertical ray strikes the mirror, find the angle between mirror and reflected ray (a) 30 (b) 45 (c) 60 (d) 90 22. A watch shows time as 3 : 25 when seen through a mirror, time appeared will be (a) 8 : 35 (b) 9 : 35 (c) 7 : 35 (d) 8 : 25 23. If an observer is walking away from the plane mirror with 6m/ sec. Then the velocity of the image with respect to observer will be (a) 6m/sec (b) − 6m / sec (c) 12m/ sec (d) 3m/sec 24. A man runs towards mirror at a speed of 15m/ s. What is the speed of his image (a) 7.5 m/s (b) 15 m/s (c) 30 m/s (d) 45 m/s 25. A small object is placed 10 cm infront of a plane mirror. If you stand behind the object 30 cm from the mirror and look at its image, the distance focused for your eye will be (a) 60 cm (b) 20 cm (c) 40 cm (d) 80 cm 26. An object is at a distance of 0.5 m in front of a plane mirror. Distance between the object and image is (a) 0.5 m (b) 1 m (c) 0.25 m (d) 1.5 m 27. A man runs towards a mirror at a speed 15 m/s The speed of the image relative to the man is (a) 15 −1 ms (b) 30 −1 ms (c) 35 −1 ms (d) 20 −1 ms 28. The light reflected by a plane mirror may form a real image (a) If the rays incident on the mirror are diverging (b) If the rays incident on the mirror are converging (c) If the object is placed very close to the mirror (d) Under no circumstances 29. Two plane mirrors are inclined at an angle of 0 72 . The number of images of a point object placed between them will be (a) 2 (b) 3 (c) 4 (d) 5 30. To get three images of a single object, one should have two plane mirrors at an angle of (a) 30° (b) 60° (c) 90° (d) 150° 31. A man of length h requires a mirror, to see his own complete image of length at least equal to (a) 4 h (b) 3 h (c) 2 h (d) h 32. Two plane mirrors are at 45 to each other. If an object is placed between them, then the number of images will be (a) 5 (b) 9 (c) 7 (d) 8 33. A man having height 6 m. He observes image of 2 m height erect, then mirror used is (a) Concave (b) Convex (c) Plane (d) None of these
34. A light beam is being reflected by using two mirrors, as in a periscope used in submarines. If one of the mirrors rotates by an angle , the reflected light will deviate from its original path by the angle (a) 2 (b) o 0 (c)  (d) 4 35. Focal length of a plane mirror is (a) Zero (b) Infinite (c) Very less (d) Indefinite 36. A ray of light is incident at 50° on the middle of one of the two mirrors arranged at an angle of 60° between them. The ray then touches the second mirror, get reflected back to the first mirror, making an angle of incidence of (a) 50° (b) 60° (c) 70° (d) 80° 37. A convex mirror of focal length f forms an image which is n 1 times the object. The distance of the object from the mirror is (a) (n − 1)f (b) f n n       −1 (c) f n n       +1 (d) (n + 1)f 38. A diminished virtual image can be formed only in (a) Plane mirror (b) A concave mirror (c) A convex mirror (d) Concave-parabolic mirror 39. Which of the following could not produce a virtual image (a) Plane mirror (b) Convex mirror (c) Concave mirror (d) All the above can produce a virtual image 40. An object 5cm tall is placed 1m from a concave spherical mirror which has a radius of curvature of 20cm The size of the image is (a) 0.11cm (b) 0.50cm (c) 0.55cm (d) 0.60cm 41. The focal length of a concave mirror is 50cm. Where an object be placed so that its image is two times and inverted (a) 75 cm (b) 72 cm (c) 63 cm (d) 50 cm 42. An object of size 7.5cm is placed in front of a convex mirror of radius of curvature 25cm at a distance of 40cm. The size of the image should be (a) 2.3cm (b) 1.78cm (c) 1cm (d) 0.8cm 43. The field of view is maximum for (a) Plane mirror (b) Concave mirror (c) Convex mirror (d) Cylindrical mirror 44. The focal length of a concave mirror is f and the distance from the object to the principle focus is x. The ratio of the size of the image to the size of the object is (a) f f + x (b) x f (c) x f (d) 2 2 x f 45. Image formed by a convex mirror is (a) Virtual (b) Real (c) Enlarged (d) Inverted 46. In a concave mirror experiment, an object is placed at a distance 1 x from the focus and the image is formed at a distance 2 x from the focus. The focal length of the mirror would be (a) x1 x2 (b) 1 2 x x (c) 2 1 2 x + x (d) 2 1 x x 47. A convex mirror is used to form the image of an object. Then which of the following statements is wrong (a) The image lies between the pole and the focus (b) The image is diminished in size (c) The image is erect (d) The image is real 48. Given a point source of light, which of the following can produce a parallel beam of light (a) Convex mirror (b) Concave mirror (c) Concave lens (d) Two plane mirrors inclined at an angle of 90 49. The image formed by a convex mirror of focal length 30cm is a quarter of the size of the object. The distance of the object from the mirror is (a) 30cm (b) 90cm (c) 120cm (d) 60cm
50. A boy stands straight infront of a mirror at a distance of 30cm away from it. He sees his erect image whose height is th 5 1 of his real height. The mirror he is using is (a) Plane mirror (b) Convex mirror (c) Concave mirror (d) Plano-convex mirror 51. A person sees his virtual image by holding a mirror very close to the face. When he moves the mirror away from his face, the image becomes inverted. What type of mirror he is using (a) Plane mirror (b) Convex mirror (c) Concave mirror (d) None of these 52. Which one of the following statements is true (a) An object situated at the principle focus of a concave lens will have its image formed at infinity (b) Concave mirror can give diminished virtual image (c) Given a point source of light, a convex mirror can produce a parallel beam of light (d) The virtual image formed in a plane mirror can be photographed 53. The relation between the linear magnification m, the object distance u and the focal length f is (a) f f u m − = (b) f u f m − = (c) f f u m + = (d) f u f m + = 54. While using an electric bulb, the reflection for street lighting should be from (a) Concave mirror (b) Convex mirror (c) Cylindrical mirror (d) Parabolic mirror 55. A concave mirror is used to focus the image of a flower on a nearby well 120cm from the flower. If a lateral magnification of 16 is desired, the distance of the flower from the mirror should be (a) 8cm (b) 12cm (c) 80cm (d) 120cm 56. A virtual image larger than the object can be obtained by (a) Concave mirror (b) Convex mirror (c) Plane mirror (d) Concave lens 57. An object is placed 40cm from a concave mirror of focal length 20cm. The image formed is (a) Real, inverted and same in size (b) Real, inverted and smaller (c) Virtual, erect and larger (d) Virtual, erect and smaller 58. A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature 36cm. The distance of the object from the mirror is (a) 5cm (b) 12cm (c) 10cm (d) 20cm 59. Radius of curvature of concave mirror is 40cm and the size of image is twice as that of object, then the object distance is (a) 60cm (b) 20cm (c) 40cm (d) 30cm 60. All of the following statements are correct except (a) The magnification produced by a convex mirror is always less than one (b) A virtual, erect, same-sized image can be obtained using a plane mirror (c) A virtual, erect, magnified image can be formed using a concave mirror (d) A real, inverted, same-sized image can be formed using a convex mirror 61. If an object is placed 10cm infront of a concave mirror of focal length 20cm, the image will be (a) Diminished, upright, virtual (b) Enlarged, upright, virtual (c) Diminished, inverted, real (d) Enlarged, upright, real 62. Which of the following form(s) a virtual and erect image for all positions of the object (a) Convex lens (b) Concave lens (c) Convex mirror (d) Concave mirror 63. A convex mirror has a focal length f. A real object is placed at a distance f in front of it from the pole produces an image at (a) Infinity (b) f (c) f / 2 (d) 2f 64. An object 1cm tall is placed 4cm infront of a mirror. In order to produce an upright image of 3cm height one needs a (a) Convex mirror of radius of curvature 12cm (b) Concave mirror of radius of curvature 12cm (c) Concave mirror of radius of curvature 4cm (d) Plane mirror of height 12cm 65. Match List I with List II and select the correct answer using the codes given below the lists :