genius PHYSICS Test class XII Ray Optics by Pradeep Kshetrapal 1. Time 1.5 hours 2. Correct answers +3 marks No answer 0 marks, Wrong answer -1 mark 3. Use blank space for calculations. 4. Return complete answer sheet Name of Student 1. A plane mirror is placed at the bottom of the tank containing a liquid of refractive index . P is a small object at a height h above the mirror. An observer O-vertically above P outside the liquid see P and its image in the mirror. The apparent distance between these two will be 2 h (a) O 2h (b) 2. P (c) 2h 1 (d) 1 h 1 h In an experiment of find the focal length of a concave mirror a graph is drawn between the magnitudes of u and v. The graph looks like v v (a) (b) u u (c) (d) v v u u 3. Centre: genius Academy Jamanipali . . . . . . . . . . . . . . . . . . . . . . A point object is placed at a distance of 10 cm and its real image is formed at a distance of 20cm from a concave mirror. If the object is moved by 0.1cm towards the mirror, the image will shift by about (a) 0.4 cm away from the mirror (b) 0.4 cm towards the mirror (c) 0.8 cm away from the mirror mirror (d)0.8 cm towards the 4. The minimum distance between the object and its real image for concave mirror is (a) f (b) 2f (c) 4f (d) Zero 5. In a concave mirror experiment, an object is placed at a distance x1 from the focus and the image is formed at a distance x 2 from the focus. The focal length of the mirror would be (a) 6. x1 x 2 (b) x1 x 2 (c) x1 x 2 2 (d) x1 x2 Radius of curvature of convex mirror is 40 cm and the size of object is twice as that of image, then the image distance is (a) 10 cm (b) 20 cm (c) 40 cm (d) 30 cm 7. A short linear object of length l lies along the axis of a concave mirror of focal length f at a distance u form the pole of the mirror. The size of the image is approximately equal to (a) u l f f l u 1/2 f (b) 1/2 f (d) u l f f f l u 2 (c) f 2 8. A rectangular slab of refractive index is placed over another slab of refractive index 3, both slabs being identical in dimensions. If a coin is placed below the lower slab, for what value of will the coin appear to be placed at the interface between the slabs when viewed from the top (a) 1.8 (b) 2 (c) 1.5 (d) 2.5 9. A glass prism of refractive index 1.5 is immersed in water ( 4 / 3) . A light beam incident normally on the face AB is totally reflected to reach the face BC if B A C (a) (c) sin 8 / 9 sin 2 / 3 (b) 2 / 3 sin 8 / 9 (d) cos 8 / 9 10. In a thin spherical fish bowl of radius 10 cm filled with water of refractive index 4/3 there is a small fish at a distance of 4 cm from the centre C as shown in figure. Where will the image of fish appears, if seen from E E C 4 cm (a) 5.2 cm (b) 7.2 cm (c) 4.2 cm (d) 3.2 cm 11. A thin lens focal length f1 and its aperture has diameter d. It forms an image of intensity I. Now the central part of the aperture upto diameter d/2 is blocked by an opaque paper. The focal length and image intensity will change to (a) f I and 2 2 (b) f and I 4 (c) I 3f and 4 2 (d)f and 3I 4 12. Figure given below shows a beam of light converging at point P. When a concave lens of focal length 16 cm is introduced in the path of the beam at a place O shown by dotted line, the beam converges at a distance x from the lens. The value x will be equal to (a) 12 cm (b) 24 cm (c) 36 cm (d) 48 cm P 12 cm O 13. A thin double convex lens has radii of curvature each of magnitude 40 cm and is made of glass with refractive index 1.65. Its focal length is nearly (a) 20 cm (b) 31 cm (c) 35 cm (d) 50 cm 14. Two point light sources are 24 cm apart. Where should a convex lens of focal length 9 cm be put in between them from one source so that the images of both the sources are formed at the same place (a) 6 cm (b) 9 cm (c) 12 cm (d) 15 cm 15. A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3/4 of the angle of the prism. The angle of deviation is (a) 45o (b) 39o (c) 20o (d) 30o 16. A prism having an apex angle 4o and refraction index 1.5 is located in front of a vertical plane mirror as shown in figure. Through what total angle is the ray deviated after reflection from the mirror 4° (a) (c) 176o 178o (b) (d) 4o 2o 17. The focal lengths of the objective and the eye-piece of a compound microscope are 2.0 cm and 3.0 cm respectively. The distance between the objective and the eye-piece is 15.0 cm. The final image formed by the eyepiece is at infinity. The two lenses are thin. The distances in cm of the object and the image produced by the objective measured from the objective lens are respectively (a) 2.4 and 12.0 (b) 2.4 and 15.0 (c) 2.3 and 12.0 (d) 2.3 and 3.0 18. The magnifying power of an astronomical telescope is 8 and the distance between the two lenses is 54cm. The focal length of eye lens and objective lens will be respectively (a) 6 cm and 48 cm (b) 48 cm and 6 cm (c) 8 cm and 64 cm (d) 64 cm and 8 cm 19. A person wears glasses of power –2.0 D. The defect of the eye and the far point of the person without the glasses will be (a) Nearsighted, 50 cm (b) Farsighted, 50 cm (c) Nearsighted, 250 cm (d) Astigmatism, 50 cm 20. A telescope consisting of object glass of power + 2 D and eye-glass of power + 20 D is focussed on an object 1m from the object glass. The final image is seen with completely relaxed eye. The magnifying power of the telescope is (a) 20 (b) 41 (c) 24 (d) 49.2 MARK YOUR ANSWERS HERE Qn.No. a b c d Qn. No. a b c d 1 O O O O 11 O O O O 2 O O O O 12 O O O O 3 O O O O 13 O O O O 4 O O O O 14 O O O O 5 O O O O 15 O O O O 6 O O O O 16 O O O O 7 O O O O 17 O O O O 8 O O O O 18 O O O O 9 O O O O 19 O O O O 10 O O O O 20 O O O O

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