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Ray Optics, , PROBLEMS & OVERVIEW
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Single choice questions (Level 0), 1., , 2., , 3., , 4., , 5., , 6., , A ray of light incidents on a plane mirror at an, angle of 300.The deviation produced in the ray is, (a) 300, (b) 600, 0, (c) 90, (d) 1200, A ray of light is incidenting normally on a plane, mirror. The angle of reflection will be, (a) 00, (b) 900, (c) Will not be reflected (d) none of the above, 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 θ, the, reflected light will deviate from its original path by, the angle, (a) 2θ, (b) 00, (c) θ, (d) 4θ, 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, mirror be parallel to each other, Two plane mirrors. A and B are aligned parallel to, each other,, B, 2√3 m, as shown in, the figure., 0.2 m, A light ray, 300, is incident, at an angle, A, of 30 at a, point just inside one end of A. The plane of, incidence coincides with the plane of the figure., The maximum number of times the ray undergoes, reflections (including the first one) before it, emerges out is, (a) 30, (b) 31, (c) 32, (d) 34, A plane mirror rotating at an angular velocity of 3, radian/s a light beam. The angular velocity of the, reflection beam is:, (a) 3 rad/s (b) 6 rad/s (c) 9 rad/s (d) 12 rad/s, , 7. Two plane mirrors are arranged at right angles to, each other as shown in the figure. A ray of light is, incident on the, horizontal, , mirror at an angle . For, what value of the ray, emerges parallel to the, incoming ray after reflection, from the vertical mirror, (a) 60°, (c) 45°, (b)30° (d) all of the above, 8. Two plane mirrors are inclined at, A, angle as shown in the figure. If, a ray parallel to OB strikes the, P, other mirror at P and finally, emerges parallel to OA after two, reflections then is equal to, , B, (a) 90°, (b) 45°, O, (c)60°, (d) 30°, 9. To get three images of a single object, one should, have two plane mirrors at an angle, (a) 60°, (b) 90°, (c) 120°, (d) 30°, 10 A light bulb is placed between two plane mirrors, inclined at an angle of 600. The no. Of images, formed are, (a) 6, (b) 2, (c) 5, (d) 4, 11. A man runs towards a mirror at a speed 15 m/s The, speed of the image relative to the man is, (a)15 m/s (b)30 m/s, (c) 35 m/s (d)20 m/s, 12., , 13., , Two plane mirrors are inclined at an angle of 72 0 ., The number of images of a point object placed, between them will be, (a) 2, (b) 3, (c) 4, (d) 5, 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) 6 m/sec, (b) -6 m/sec, (c) 12 m/sec, (d) 3 m/sec
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d, , 14., , 15., , 16., , 17., , 18., , A small object is placed 10cm in front 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, 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, A man of length h requires a mirror, to see his own, complete image of length at least equal, (a) h/4, (b) h/3, (c) h/2, (d) h, Two vertical plane mirrors are inclined at an angle, of 600 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) 600, (b) 1200, (c) 1800, (d) 2400, When a plane mirror is rotated through an angle θ, then the reflected ray turns through the angle 2θ, then the size of the image, (a) Is doubled, (b) Is halved, (c) Remains the same, (d) Becomes infinite, , Single choice questions (Level 1), 19., , A point source of light B is placed at a distance L, in front of the centre of a mirror of width d hung, vertically on a wall. A man walks in front of the, mirror along a line parallel to the mirror at a, distance 2L from it as shown. The greatest distance, over which he can see the image of the light source, in the mirror is, (a) d/2, , B, , L, (b) d, A, 2L, (c) 2d, (d) 3d, 20. 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, 21. When a plane mirror is placed horizontally on a, level ground at a distance of 60 m from the foot of a, tower, the top of the tower and its image in the, mirror subtend an angle of 900 at the eye. The height, of the tower will be, (a) 30 m, (b) 60 m, (c) 90 m, (d) 120 m, , 22., , A motorcyclist approaches towards a bus 2with, speed u. At the back of the bus the plane mirrors. The, bus moves with speed v. what is the relative velocity, of the cyclist relative to his image in the mirror (u >, v), (a) u - 2v, (b) 2u - v, (c) 2(u – v), (d) none, 23. The minimum size of a plane mirror hung on a wall, of a room in which an observer standing at the centre, can see the total height of the wall behind him is, (take the height of the wall to be H)., (a) H/2, (b) H/3, (c) H/4, (d) H, 24. A point object O is placed between two plane mirrors, as shown in the figure. The distance of the first three, images formed by mirror M2 from it are:, (a) 2 mm, 8 mm, 18 mm, M1, M2, 10 mm, (b) 2 mm, 18 mm, 28 mm, (c) 2 mm, 18 mm, 22 mm, O, (d) 2 mm, 18 mm, 38 mm, , REFLECTION through SPHERICAL SURFACES, PROBLEMS & OVERVIEW, , 2 mm
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4., , 5., , 6., , Single choice, , 7., , questions (Level 0), 1., , 2., , 3., , 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, Focal length of a plane mirror is, (a) Zero, (b) infinite, (c) very less, (d) indefinite, Given a point source of light, which of the, following can produce a parallel beam of light, , 8., , (a) Convex mirror, (b) Concave mirror, (c) Concave lens, (d) Two plane mirrors inclined at an angle of 90, A virtual image larger than the object can be, obtained by, (a) Concave mirror, (b) Convex mirror, (c) Plane mirror, (c) Concave lens, 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, 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, A concave mirror gives an image three times as, large as the object placed at a distance of 20cm, from it. For the image to be real, the focal length, should be, (a) 10cm, (b) 15cm, (c) 20cm, (d) 30cm, Under which of the following condition will a, convex mirror of focal length f produce an image, that is erect, diminished and virtual, (a) Only when 2f > u > f, (b) Only when u = f, (c) Only when u < f
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9., , 10., , 11, , 12., , 13., , 14., , 15., , 16., , (d) Always, Convergence of concave mirror can be decreased, by dipping in, (a) Water, (b) Oil, (c) Both, (d) None of these, An object 5 cm 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, Image formed by a convex mirror is, (a) Virtual, (b) Real, (c) Enlarged, (d) Inverted, 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) 5 cm, (b) 12cm, (c) 10cm, (d) 20cm, An object 1cm tall is placed 4cm in front 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 a radius of curvature 4cm, (d) Plane mirror of height 12cm, An object 2.5cm high is placed at a distance of, 10cm from a concave mirror of radius of radius of, curvature 30cm. The size of image is, (a) 9.2 cm, (b) 10.5 cm, (c) 5.6 cm, (d) 7.5cm, An object of length 6 cm is placed on the principle, axis of a concave mirror of focal length f at a, distance of 4f. The length of the image will be, (a) 2 cm, (b) 12 cm, (c) 4 cm, (d) 1.2 cm, A concave mirror of focal length f (in air) is, immersed in water ( 4 / 3 ). The focal length of, the mirror in water will be, (a) f, (c), , 3, f, 4, , (b), , 4, f, 3, , (d), , 7, f, 3, , 19., , 20., , In a concave mirror experiment, an object is placed, at a distance x 1 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) x 1 x 2, (c), , 18., , x1 x 2, 2, , (b), , x1 x 2, , (d), , x1, x2, , A concave mirror is used to focus the image of a, flower on a nearby wall 120cm from the flower. If, , List I, , List II, , (Position of the object), , (Magnification), , (I) An object is placed at (A) Magnification is, focus before a convex , mirror, (II) An object is placed (B) Magnification is, at centre of curvature 0.5, before a concave mirror, (III) An object is placed (C) Magnification is, at focus before a 1, concave mirror, (IV) An object, placed at centre, curvature before, convex mirror, , is (D) Magnification is –, of 1, a, (E) Magnification is, 0.33, , 21., , 22., , Single choice questions (Level 1), 17., , 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, 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, uring a concave mirror, (d) A real, inverted, same-sized image can be, formed using a convex mirror, Match List I with List II and select correct answer, using the codes given below the lists:, , 23, , (a) I-B,II-D,III-A,IV-E (b) I-A,II-D,III-C,IV-B, (c) I-C,II-B,III-A,IV-E (d) I-B,II-E,III-D,IV-C, Under which of the following condition will a, convex mirror of focal length f produce an image, that is erect, diminished and virtual, (a) Only when 2f > u > f, (b) Only when u = f, (c) Only when u < f, (d) Always, For a real object, which of the following can, produced a real image, (a) Plane mirror, (b) Concave lens, (c) Convex mirror, (d) Concave mirror, A thin rod of length f / 3 lies along the axis of a, concave mirror of focal length f . One end of its, magnified image touches an end of the rod. The, length of the image is, (a) f, , (b), , 1, f, 2
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(c) 2 f, , (d), , v, , 1, f, 4, , 24. A concave mirror has a focal length 20 cm. The, distance between the two positions of the object for, which the image size is double of the object size is, (a) 20 cm (b) 40 cm (c) 30 cm, (d) 60 cm, 25. A luminous object is placed 20 cm from the surface, of a convex mirror and a plane mirror is set so that, the virtual images formed in the, two mirrors, coincide. If the plane mirror is at a distance of 12 cm, from the object, then the focal length of the convex, mirror, is, (a) 10 cm (b) 5 cm, (c) 20 cm, (d) 40 cm, 26. A short linear object of length b lies along the axis, of a concave mirror of focal length f at a distance u, from the pole of the mirror. The size of the image is, approximately equal to, , u f , , (a) b, f , , 1/ 2, , u f , , (c) b, f , , f , , (b) b, u f , f , , (d) b, u f , , 2, , f u, v0, f , , (c) , , u, , (a), , (c), , u, , (d), , u, , 29. The diagram shows a mirror system. If after two, reflections the image and the object coincide with, each other then the value of radius of curvature of the, concave mirror is equal to, 4a, O, a, , 2, , (a) 16a/3, (c) 8a/3, , (b) 4a/3, (d) None, , 2, , (d) N.O.T., , 28. As the position of an object (u) reflected from a, concave mirror is varied, the position of the image, (v) also varies. By letting the u changes from 0 to +, the graph between v versus u will be, , through, , u, , v, , f v, (b) , v0, f , , Refraction, , (b), , v, , 1/ 2, , 27. If an object is moving towards a spherical mirror, along its axis at a speed v0, find the speed at which, the image of this object is moving., , f v, (a) , v0, f , , v, , Plane surfaces, , PROBLEMS & OVERVIEW
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Snell’s Law, , 4., , 5., , Single choice questions (Level 0), 1.., , 2., , 3., , To an observer on the earth the stars appear to, twinkle. This can be ascribed to, (a) The fact that stars do not emit light, continuously, (b) Frequent absorption of star light by their own, atmosphere, (c) Frequent absorption of star light by the earth’s, atmosphere, (d) The refractive index fluctuations in the earth’s, atmosphere, The refractive index of a certain glass is 1.5 for, light whose wavelength in vacuum is 6000 Ǻ. The, wavelength of this light when it passes through, glass is, (a) 4000 Ǻ, (b) 6000 Ǻ, (c) 9000 Ǻ, (d) 15000 Ǻ, When light travels from one medium to the other, of which the refractive index is different, then, which of the following will change, (a) Frequency, wavelength and velocity, (b) Frequency and wavelength, (c) Frequency and velocity, (d) Wavelength and velocity, , 6., , 7., , 8., , 9., , 10., , A light wave has a frequency of 4×1014 Hz and a, wavelength of 5×10-7 meters in a medium. The, refractive index of the medium is, (a) 1.5, (b) 1.33, (c) 1.0, (d) 0.66, Light travels through a glass plate of thickness t, and having refractive index n. If c is the velocity, of light in vacuum, the time taken by the light to, travel this thickness of glass is, (a), , t, nc, , (b) tnc, , (c), , nt, c, , (d), , tc, n, , When a light wave goes from air water, the quality, that remains unchanged is its, (a) Speed, (b) Amplitude, (c) Frequency, (d) Wavelength, The refractive index of glass and water w.r.t. Air, are 3/2 and 4/3 respectively. The refractive index, of glass w.r.t. Water will be, (a) 8/9, (b) 9/8, (c) 7/6, (d) None of these, If the speed of light in vacuum is C m/s, then the, velocity of light in a medium of refractive index, 1.5 is, (a) 1.5×C (b) C, (c) C/1.5, (d) Can have any velocity, The refractive index of water is 1.33. What will be, the speed of light in water, (a) 3×108 m/s, (b) 2.25×108 m/s, (c) 4×108 m/s, (d) 1.33×108 m/s, The frequency of a light ray is 6×1014 Hz. Its, frequency when it propagates in a medium of, refractive index 1.5, will be, (a) 1.67×1014Hz, (b) 9.10×1014Hz
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(c) 6×1014Hz, 11., , 12., , (d) 4×1014H, , Refractive index of glass is 3/2 and refractive index, of water is 4/3. If the speed of light in glass is, 2.00×108 m/s, the speed in water will be, (a) 2.67×108 m/s, (b) 2.25×108 m/s, (c) 1.78×108 m/s, (d) 1.50×108 m/s, Monochromatic light of frequency 5×1014 Hz, travelling in vacuum inter a medium of refractive, index 1.5. Its wavelength in the medium is, (a) 4000 Ǻ, (b) 5000 Ǻ, (c) 6000 Ǻ, (d) 5500 Ǻ, , 18. The face PR of a prism PQR of, angle 30° is silvered. A ray is, incident on the face PQ at an, angle of 45° as shown in the, figure. The refracted ray, undergoes reflection on face PR, and retraces its path. The, refractive index of the prism is, (a) 2, (b) 3/2 (c) 1.5, , P, 45, °, R, Q, , (d) 1.33, , Total internal reflection, , Single choice questions (Level 1), 13., , On a glass plate a light wave is incident at an angle, of 600. If the reflected and the refracted waves are, mutually perpendicular, the refractive index of, material is, (a) 3/2, (b) under root 3, (c) 3/2, (d) 1/3, , 14., , What is the time taken (in seconds) to cross a glass, of thickness 4 mm and µ = 3 by light, (a) 4×10-11, (b) 2×10-11, -11, (c) 16×10, (d) 8×10-10, , 15. A ray of light from denser medium strikes a rarer, medium at an angle of, incident i as shown in the, figure. The reflected and Denser i, r, refracted rays make an angle medium, 90°, of 90° with each other. The, D, Rarer, angles of reflection and medium, r, refraction and r and r, respectively. The critical, angle is, (a) sin1 (cot r), (b) sin1 (tan r), (c) sin1 (tan i), (d) None of these, 16. One side of a glass slab is silvered as shown. A ray, of light is incident on, 450, the other side at angle, of incidence i = 45°., Refractive index of, μ = 1.5, glass is given as 1.5., The deviation of the ray, of light from its initial path when it comes out of the, slab is, (a) 90°, (b) 180°, (c) 120°, (d) 45°, 17. A diverging beam of light from a point source S, S, having divergence angle α ,, α, falls symmetrically on a glass, i, i, slab as shown. The angles of, incidence for the two extreme, n, rays are equal. If the thickness, of the slab of t and refractive is, n, then the divergence angle of the emergent beam is, (a) zero, (b) α, (c) sin-1(1/n) (d) 2 sin-1 (1/n), , Single choice questions (Level 0), 19., , A cut diamond sparkles because of its, (a) Hardness, (b) High refractive index, (c) Emission of light by the diamond, (d) Absorption of light by the diamond, , 20., , If the critical angle for total internal reflection from, a medium to vacuum is 30°, the velocity of light in, the medium is, (a) 3 10 8 m/s, (b) 1.5 10 8 m/s, (c) 6 10 8 m/s, (d) 3 10 8 m/s, , 21., , A diver at a depth of 12m in water ( 4 / 3) sees, the sky in a cone of semi-vertical angle, (a) sin1 (4 / 3), (b) tan 1 (4 / 3), , 22., , 23., , (c) sin1 (3 / 4 ), (d) 90°, 'Mirage' is a phenomenon due to, (a) Reflection of light, (b) Refraction of light, (c) Total internal reflection of light, (d) Diffraction of light, The phenomenon utilised in an optical fibre is, (a) Refraction, (b) Interference, (c) Polarization, (d), Total, internal, reflection
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24., , A ray of light propagates from glass (refractive, index = 3/2) to water (refractive index = 4/3). The, value of the critical angle, , 32., , Consider telecommunication through optical fibres., Which of the following statements is not true, (a) Optical fibres may have homogeneous core, with a suitable cladding, (b) Optical fibres can be of graded refractive index, (c) Optical fibres are subject to electromagnetic, interference from outside, (d) Optical fibres have extremely low transmission, loss, , 33., , The critical angle of a medium with respect to air is, 45 o . The refractive index of medium is, (a) 1.41, (b) 1.2, (c) 1.5, (d) 2, , 8, , sin1 , 9 , , , , (a) sin–1(1/2), , (b), , (c) sin1 (8 / 9), , (d) sin1 (5 / 7), , 25., , Relation between critical angles of water and glass, is, (a) Cw > Cg, (b) Cw < Cg, (c) Cw = Cg, (d) Cw = Cg = 0, , 26., , The refractive index of water is 1.33. The direction in, which a man under water should look to see the, setting sun is, (a) 49o to the horizontal, (b) 90o with the vertical, (c) 49o to the vertical, (d) Along the horizontal, , 27., , (d) The angle of incidence, , Single choice questions (Level 1), 34. If light travels a distance x in t1 sec in air and 10 x, distance in t2 sec in a medium, the critical angle of of, the medium will be, , t , , refractive index of water is, , 4, 3, , 28, , (c) 36 7, , (d) 36 / 7, , 1, , sin i, , (c) sin i , 29., , 30., , 31., , 35., , For total internal reflection to take place, the angle, of incidence i and the refractive index of the, medium must satisfy the inequality, (a), , (b), , 1, , sin i, , 36., , (d) sin i , , The critical angle for diamond (refractive index =, 2) is, (a) About 20°, (b) 60°, (c) 45°, (d) 30°, , (d) tan 1 , , The velocity of light in a medium is half its, velocity in air. If ray of light emerges from such a, medium into air, the angle of incidence, at which it, will be totally internally reflected, is, (a) 15o, (b) 30 o, o, (c) 45, (d) 60 o, A light ray from air is incident (as shown in figure), at one end of a glass fiber (refractive index = 1.5), making an incidence angle of 60o on the lateral, surface, so that it undergoes a total internal, reflection. How much time would it take to, traverse the straight fiber of length 1, Air, Air, , The reason for shining of air bubble in water is, (a) Diffraction of light, (b) Dispersion of light, (c) Scattering of light, (d) Total internal reflection of light, When a ray of light emerges from a block of glass,, the critical angle is, (a) Equal to the angle of reflection, (b) The angle between the refracted ray and the, normal, (c) The angle of incidence for which the refracted, ray travels along the glass-air boundary, , 10t1 , , t2 , , (c) sin 1 1 , t2 , , below the surface, the radius of this circle in cm is, (b) 4 5, , (b) sin 1 1 , t2 , , 10t , , and the fish is 12 cm, , (a) 36 5, , t , , (a) tan 1 1 , t2 , , A fish looking up through the water sees the, outside world contained in a circular horizon. If the, , 60o, , Glass, , km, (a) 3.33 sec, (b) 6.67 sec, (c) 5.77 sec, (d) 3.85 sec, 37., , Critical angle for light going from medium (i) to, (ii) is . The speed of light in medium (i) is v then, speed in medium (ii) is, (a) v(1 cos ), (b) v / sin, (c) v / cos , (d) v(1 sin )
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(b) 2/3 < sin < 8/9, 38., , 39., , A triangular prism of glass is shown in the figure., A ray incident normally to one face is totally, reflected, if 45 o . The index of refraction of, glass is, (a) Less than 1.41, (b) Equal to 1.41, , (c) Greater than 1.41, 45o, (d) None of the above, , (d) none of these, , Image formation through a parallel faced slab:, , A ray of light is incident at the glass–water, interface at an angle i, it emerges finally parallel to, the surface of water, then the value of g would be, (a) (4/3) sin i, (b) 1/sin i, (c) 4/3, (d) 1, , Single choice questions (Level 0), w = 4/3, , Water r, , r, Glass, , i, , 40. Critical angle of glass is 1 and that of water is 2., The critical angle for water and glass surface would, be (µg = 3/2, µw = 4/3), (a) less than 2, (b) between 1 and 2, (c) greater than 2, (d) less than 1, 41. Light is incident normally, liquid, on face AB of a prism as, shown in the figure. A A, C, 60°, 30°, liquid of refractive index, µ is placed on face AC of, 90°, the prism. The prism is, B, made, of, glass, of, refractive index 3/2. The limits of µ for which total, internal reflection takes place on face AC i s, (a) µ , , 3, 3 3, (b) µ , (c) µ 3, 2, 4, , (d) µ , , 3, 2, , 42., , A light ray is, A, incident normally, on the face AB of a, light angle prism, α, B, C, ABC (n = 1.5) as, shown. The, largest angle of α for which the light ray totally, reflected at the surface AC is, (a) cos-1 (3/2) (b) cos-1 (2/3)(c) sin-1 (2/3) (d) sin-1 (3/2), b, , 44. The image of point P when, viewed from top of the, slabs will be, µ=1.5, 1.5 cm, (a) 2.0 cm above P, 1.5 cm, (b) 1.5 cm above P, µ=1.5, 1.5 cm, (c) 2.0 cm below P, (d) 1 cm above P, 2 cm, P, 45. A fish at a depth of 12 cm, in water is viewed by an observer on the bank of, lake. To what height the image of the fish is raised, (a) 9 cm, (b) 12 cm, (c) 3.8 cm, (d) 3 cm, 46. A vessel of depth 2d cm is half filled with a liquid, of refractive index 1 and the upper half with a liquid of, refractive index 2 . The apparent depth of the vessel, seen perpendicularly is, , , 1, , 1 , , 1, , 1 , , (b) d , 1 2 , 1 , , , (c) 2d , (d) 2d , , 1 2 , 1 2 , 47. A beam of light is converging towards a point I on, a screen. A plane glass plate whose thickness in the, direction of the beam = t , refractive index = , is, introduced in the path of the beam. The, convergence point is shifted by, , , 1, , , , , , (a) t 1 away, , , , 1, , , , , , (c) t 1 nearer, , 48., , a, , 43. A glass prism of, , refractive index 1.5 is, immersed in water as, d, shown in the figure. A, beam of light incident, normally on the face ab is internally reflected from, the face ad. Given that refractive index of glass is 3/2, and that of water is 4/3, what is the value of ?, (a) sin > 8/9, (c) sin < 2/3, , , , (a) d 1 2 , 1 2 , , 49., , , , 1, , , , , , (b) t 1 away, , , , 1, , , , , , (d) t 1 nearer, , , The ratio of thickness of plates of two transparent, mediums A and B of 6:4. If light takes equal time, in passing through them. Then refractive index of, B with respect to A will be, (a) 1.4, (b) 1.5, (c) 1.75, (d) 1.33, Each quarter of a vessel of depth H is filled with, liquids of refractive indices n1,n2,n3 and n4 from the, bottom respectively. The apparent depth of the, vessel when looked normally is, (a), , (b)
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(c), , , , (d), , 50. A tank contains a slab of glass 8 cm thick and of, refractive index 1.6. Above this is a depth of 4.5 cm, of an oil and upon this floats a layer of water 6 cm, thick and of refractive index 4/3. To an observer, looking down from above, a mark at the bottom of, the glass slab appears to be raised up to position 6 cm, from the bottom of the slab. The refractive index of, oil is, (a) 0.8, (b) 1.2, (c) 1.5, (d) 1.8, , Single choice questions (Level 1), 51., , An under water swimmer is at a depth of 12m, below the surface of water. A bird is at a height of, 18m from the surface of water, directly above his, eyes. For the swimmer the bird appears to be at a, distance from the surface of water equal to, (Refractive Index of water is 4/3, (a) 24m, (b) 12m, (c) 18m, (d) 9m, 52. How much water should be filled in a container 21, cm in height, so that it appears half filled when, viewed from the top of the container ( given that, a = 4/3 ), (a) 8.0 cm, (b) 10.5 cm, (c) 12.0 cm, (d) None of the above, 53. Consider the situation shown in the figure. Water, (µw = 4/3) is fitted in a beaker, upto a height of 10 cm. A, 5 cm, plane mirror is fixed at a, height of 5 cm from the, surface of water. Distance of, 10 cm, image from the mirror after, reflection from it of an object, O, O at the bottom of the beaker, is, (a) 15 cm (b) 12.5 cm (c) 7.5 cm, (d) 10 cm, 54. A plane mirror is placed at the bottom of a tank, containing a liquid of, O, refractive index μ. P is a, small object at a height h, above the mirror. An, observer O-vertically above P,, P, outside the liquid-sees P and, h, its image in the mirror. The, apparent distance between, these two will be, (a) 2μh (b), , 2h, , , , (c), , 2h, 1, , , , (d) h1 , , , , 1, , , , 55. A stationary swimmer S, inside a liquid of refractive, index μ1 , is at a distance d from fixed point P inside, the liquid. A rectangular block of width t and, refractive index μ2 (μ2< μ1) is now placed between S, and P . S will observe P to be at a distance, , , , (a) d t 1 1, 2, , , , , , , (c) d t 1 2 , 1 , , , , , , , (b) d t 1 2 , 1 , , , , , , , (d) d t 1 1, 2, , , 56. A ball is dropped from a height of 20 m above the, surface of water in a lake. The refractive index of, water is 4.3. A fish inside the lake, in the line of fall, of the ball, is looking at the ball. At an instant,, when the ball is 12.8 m above the water surface, the, fish sees the speed of ball as [Take g = 10 m/s2.], (a) 9 m/s, (b) 12 m/s, (c) 16 m/s (d) 21.33 m/s, , Prism Theory, , Single choice questions (Level 0), 57. A prism ( 1.5) has the refracting angle of 30°., The deviation of a monochromatic ray incident normally, on its one surface will be (sin 48° 36’ = 0.75), (a) 18° 36’, (b) 20° 30’, (c) 18°, (d) 22°1’, 58. Angle of minimum deviation for a prism of, refractive index 1.5 is equal to the angle of prism. The, angle of prism is (cos 41° = 0.75), (a) 62°, (b) 41°, (c) 82°, (d) 31°, 59. The angle of minimum deviation for a prism is 40°, and the angle of the prism is 60°. The angle of, incidence in this position will be, (a) 30°, (b) 60°, (c) 50°, (d) 100°, 60. Deviation of 5° is observed from a prism whose, angle is small and whose refractive index is 1.5., The angle of prism is, (a) 7.5°, (b) 10°, (c) 5°, (d) 3.3°, 61. 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) 45°, (b) 39°, (c) 20°, (d) 30°
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62., , 63., , 64., , If the refractive index of a material of equilateral, prism is 3 , then angle of minimum deviation of, the prism is, (a) 30°, (b) 45°, (c) 60°, (d) 75°, The angle of minimum deviation measured with a, prism is 30° and the angle of prism is 60°. The, refractive index of prism material is, (a) 2, (b) 2, (c) 3/2, (d) 4/3, The minimum deviation produced by a hollow, prism filled with a certain liquid is found to be 30°., The light ray is also found to be refracted at angle, of 30°. The refractive index of the liquid is, (a) 2, (c), , 65., , 66., , 67., , 68., , 69., , 70., , 3, 2, , (b) 3, (d), , 3, 2, , The path of a refracted ray of light in a prism is, parallel to the base of the prism only when the, (a) Light is of a particular wavelength, (b) Ray is incident normally at one face, (c) Ray undergoes minimum deviation, (d) Prism is made of a particular type of glass, The angle of a prism is 60° and its refractive index, is 2 . The angle of minimum deviation suffered, by a ray of light in passing through it is, (a) About 20°, (b) 30°, (c) 60°, (d) 45°, Under minimum deviation condition in a prism, if, ray is incident at an angle 30o, the angle between, the emergent ray and the second refracting surface, of the prism is, (a) 0o, (b) 30 o, (c) 45 o, (d) 60 o, A ray of light is incident normally on one of the face, of a prism of angle 30o and refractive index 2 ., The angle of deviation will be, (a) 26o, (b) 0 o, (c) 23 o, (d) 15 o, Which one of the following alternative is FALSE, for a prism placed in a position of minimum, deviation, (a) i1 = i2, (b) r1 = r2, (c) i1 = r1, (d) All of these, , A given ray of light suffers minimum deviation in, an equilateral prism P. Additional prisms Q and R, of identical shape and material are now added to P, as shown in the figure. The ray will suffer, (a) Greater deviation, Q, (b) Same deviation, P, R, (c) No deviation, (d) Total internal reflection, , 71., , A ray of light is incident on an equilateral glass, prism placed on a horizontal table. For minimum, deviation which of the following is true, R, , Q, (a) PQ is horizontal, S, (b) QR is horizontal, P, (c) RS is horizontal, (d) Either PQ or RS is horizontal, 72. A ray incident a 15 o on one refracting surface of a, prism of angle 60 o , suffers a deviation of 55 o ., What is the angle of emergence, (a) 95 o, (b) 45 o, (c) 30 o, (d) None of these, 73. A ray of light passing through a prism of refracting, angle 60° has to deviate by at an least 30°. The, refractive index of prism should be, (a) 2, (b) 2, (c) 3, (d) 3, , Single choice questions (Level 1), 74., , 75., , 76., , 77., , When light of wavelength is incident on an, equilateral prism kept in its minimum deviation, position, it is found that the angle of deviation, equals the angle of the prism itself. The refractive, index of the material of the prism for the, wavelength is, then, 3, 2, , (a) 3, , (b), , (c) 2, , (d) 2, , A ray of light is incident at an angle of 60° on one, face of a prism of angle 30°. The ray emerging out, of the prism makes an angle of 30° with the, incident ray. The emergent ray is, (a) Normal to the face through which it emerges, (b) Inclined at 30° to the face through which it, emerges, (c) Inclined at 60° to the face through which it, emerges, (d) None of these, Angle of a prism is 30° and its refractive index is, 2 and one of the surface is silvered. At what, angle of incidence, a ray should be incident on one, surface so that after reflection from the silvered, surface, it retraces its path, (a) 30°, (b) 60°, (c) 45°, (d) sin1 1.5, A ray of monochromatic light is incident on one, refracting face of a prism of angle 75°. It passes, through the prism and is incident on the other face, at the critical angle. If the refractive index of the, material of the prism is 2 , the angle of incidence, on the first face of the prism is, (a) 30°, (b) 45°
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(c) 60°, 71., , (d) 0°, , When a glass prism of refracting angle 60o is, immersed in a liquid its angle of minimum deviation, is 30o. The critical angle of glass with respect to the, liquid medium is, (a) 42o, (b) 45 o, (c) 50 o, (d) 52 o
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PROBLEMS & OVERVIEW, , cross mark is viewed directly from above. The, position of the images will be ], (a) (i) 0.04 m from the flat face; (ii) 0.025 m from, the flat face, (b) (i) At the same position of the cross mark; (ii), 0.025 m below the flat face, (c) (i) 0.025 m from the flat face; (ii) 0.04 m from, the flat face, (d) For both (i) and (ii) 0.025 m from the highest, point of the hemisphere, , Refraction through A Spherical Boundary, , Thin lens, Single choice questions (Level 1), 1., , 2., , 3., , A point object O is placed in front of a glass rod, having spherical end of radius of curvature 30 cm., The image would be formed at, (a) 30 cm left, O Air, (b) Infinity, Glass, (c) 1 cm to the right, 30 cm, 15 cm, (d) 18 cm to the left, A point object is placed at the center of a glass, sphere of radius 6 cm and refractive index 1.5. The, distance of the virtual image from the surface of, the sphere is, (a) 2 cm, (b) 4 cm, (c) 6 cm, (d) 12 cm, A glass hemisphere of radius 0.04 m and R.I. of the, material 1.6 is placed centrally over a cross mark, on a paper (i) with the flat face; (ii) with the curved, face in contact with the paper. In each case the, , Single choice questions (Level 0), 4., , 5., , A convex lens of focal length 40 cm is in contact, with a concave lens of focal length 25 cm. The, power of combination is, (a) – 1.5 D, (b) – 6.5 D, (c) + 6.5 D, (d) + 6.67 D, Two lenses of power +12 and – 2 diopters are, placed in contact. What will the focal length of, combination, (a) 10 cm, (b) 12.5 cm, (c) 16.6 cm, (d) 8.33 cm, , page- 15 -
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6., , 7., , 8., , 9., , If in a plano-convex lens, the radius of curvature of, the convex surface is 10 cm and the focal length of, the lens is 30 cm, then the refractive index of the, material of lens will be, (a) 1.5, (b) 1.66, (c) 1.33, (d) 3, A converging lens is used to form an image on a, screen. When upper half of the lens is covered by, an opaque screen, (a) Half the image will disappear, (b) Complete image will be formed of same, intensity, (c) Half image will be formed of same intensity, (d) Complete image will be formed of decreased, intensity, An object is placed at a distance of 20 cm from a, convex lens of focal length 10 cm. The image is, formed on the other side of the lens at a distance, (a) 20 cm, (b) 10 cm, (c) 40 cm, (d) 30 cm, Two thin lenses of focal lengths f1 and f2 are in, contact and coaxial. The combination is equivalent, to a single lens of power, (a) f1 f2, (c), , 1, ( f1 f2 ), 2, , (b), , f1 f2, f1 f2, , (d), , f1 f2, f1 f2, , 10. Two identical glass (µg = 3/2) equiconvex lenses of, focal length f are kept in contact. The space between, the two lenses is filled with water (µw = 4/3). The, focal length of the combination is, (a) f, (b) f/2, (c) 4f/3, (d) 3f/4, 11. A thin glass (refractive index 1.5) lens has optical, power of – 5D in air. Its optical power in a liquid, medium with refractive index 1.6 will be, (a) -1 D, (b) 0.6D, (c) - 25 D, (d) 1 D, 12. A concave lens forms the image of an object such, that the distance between the object and image is 10, cm and the magnification produced is 1/4. The focal, length of the lens will be, (a) 8.6 cm (b) 6.2 cm, (c) 10 cm, (d) 4.4 cm, 13. A concave lens of glass, refractive index 1.5 has both, surfaces of same radius of curvature R. On, immersion in a medium of refractive index 1.75, it, will behave as a, (a) convergent lens of focal length 3.5 R, (b) convergent lens of focal length 3.0 R, (c) divergent lens of focal length 3.5 R, (d) divergent lens of focal length 3.0 R, 14. 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, , 15. Distance of an object from the first focus of an, equiconvex lens is 10 cm and the distance of its real, image from second focus is 40 cm. The focal length, of the lens is, (a) 25 cm, (b) 10 cm (c) 20 cm, (d) 40 cm, 16. A plane convex lens of refractive index 1.5 and, radius of curvature 30 cm is silvered at the curved, surface. Now this lens has been used to form the, image of an object. At what distance from this lens, an object be placed in order to have a real image of, the size of the object?, (a) 60 cm (b) 30 cm (c) 20 cm, (d) 80 cm, 17. A point object is placed on the optic axis of a convex, lens of focal length f at a distance of 2 f to the left of, it. The diameter of the lens is d. An eye is placed at a, distance of 3f to the right of the lens and a distance h, below the optic axis. The maximum value of h to see, the image is, (a) d, (b) d/2, (c) d/3, (d) d/4, 18. A converging lens is used to form an image on a, screen. When the upper half of the lens is covered by, an opaque screen, then which of the following, statements is true?, (a) half the image will disappear, (b) intensity of the image will increase, (c) complete image will be formed, (d) intensity of the image remains unchanged, 19. A plano-convex lens (μ = 1.5) having radius of, curvature 0.2 m s silvered on the curved surface. The, power of the system is, (a) 10 D, (b) 15 D, (c) -10 D, (d) -12 D, 20. The focal length of convex lens of glass (µ = 1.5) is, 2 cm. The focal length of the lens when immersed in, a liquid of refractive index = 1.25 will be, (a) 5 cm, (b) 2.4 cm, (c) 1 cm, (d) 4 cm, 21. A plano convex lens fits exactly into a plano concave, lens. Their plane surfaces are parallel to each other., If the lenses are made of different materials of, refractive indices µ1 and µ2 and R is the radius of, curvature of the curved surface of the lenses, then, focal length of the combination is, , R, µ1 µ2, R, (c), 2(µ1 µ2 ), (a), , 2R, µ2 µ1, R, (d), 2 (µ1 µ2 ), (b), , 22. An equiconvex lens is made from glass of, refractive index 1.5. If the radius of each surface is, changed from 5 cm to 6 cm then the power:, (a) remains unchanged, (b) decreases by 3.33 dioptre approximately, (c) increases by 3.33 dioptre approximately., (d) decreases by 5.5 dioptre approximately., 23. Two plano-convex lenses of radius of, curvature of the curved surface as R and µ = 1.5 will, have an equivalent focal length R. If they are placed:, , page- 16 -
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(a) in contact with each other, (b) at a distance 3R from each other, (c) at a distance R from each other, (d) None is correct, 24. A convex lens placed between an object and screen, forms a sharp image of the object on the screen. A, glass slab of refractive index µ is inserted between, object and lens. In order to obtain the sharp image on, the screen again, the object has to be displaced by a, distance x. The thickness of the glass slab is, µ, x (µ 1), µx, (a) µx, (b), (c), (d), x, (µ 1), µ, 25. A convex lens makes a real image 4 cm long on a, screen. When the lens is shifted to a new position, without disturbing the object or the screen, we get a, real image again on the screen which is 9 cm long., The length of the object is, (a) 2.25 cm (b) 6 cm (c) 6.60 cm, (d) 36 cm, 26. For a spherical surface of radius of curvature R,, separating two media of refractive index µ1 and µ2,, the two principal focal lengths are f1 and f2, respectively. Which one of the following relations is, correct?, f, f, f, f, f, f, (a) f1 = f2 (b) 2 1 (c) 2 1 (d) 2 1, µ 2 µ1, µ2, µ1, µ1 µ 2, 27. An equiconvex lens of glass (µg = 1.5) of focal length, 10 cm is silvered on one side. It will behave like a, (a) concave mirror of focal length 10 cm, (b) concave mirror of focal length 2.5 cm, (c) convex mirror of focal length 5 cm, (d) concave mirror of focal length 20 cm, 28. A convex lens produces an image of a real object on, a screen with a magnification of ½. When the lens is, moved 30 cm towards the object, the magnification, of the image on the screen is 2. The focal length of, the lens is, (a) 30 cm (b) 60 cm, (c) 20 cm, (d) 15 cm, , 29. A point object O is placed at a distance of 20 cm, from a convex lens, of focal length 10, cm as shown in the, figure. At what, distance x from O, the lens should a, 20 cm, x, concave mirror of, focal length 60, cm, be placed so that final image coincides with the, object, (a) 10 cm, (b) 40 cm, (c) 20 cm, (d) final image can never coincide with the object in, the given conditions Hint : th, 30. The plane surface of a plano-convex lens of focal, length 20 cm is silvered. It will behave as, (a) Plane mirror, (b) concave mirror of focal length 10 cm, (c) convex mirror of focal length 10 cm, (d) None of these, 31., , A thin plano-convex lens acts like a concave mirror, of focal length 0.2 m when silvered from its plane, surface. The refractive index of the material of the, lens is 1.5. The radius of curvature of the convex, surface of the lens will be, (a) 0.4 m, (b) 0.2 m, (c) 0.1 m, (d) 0.75 m, 32. A plano-convex lens of refractive index 1.5 and, radius of curvature 30 cm is silvered at the curved, surface. Now this lens has been used to form the, image of an object. At what distance from this lens, an object be placed in order to have a real image of, the size of the object, (a) 20 cm, (b) 30 cm, (c) 60 cm, (d) 80 cm, 33. Find the position of the image of the object from the, object when farthest surface is silvered as shown in, figure, (a), , 40, 11, 1611, 480, cm (b), cm (c), cm (d), cm, 11, 40, 40, 11, f1 = 12, cm, , Path retracing ,Silvering of lens, , O, , 40 cm, , R = 24 cm, , Single choice questions (Level 1), page- 17 -
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OPTICAL INSTRUMENTS:, , 4., , Eye lens, , 5., , 6., , Single choice questions (Level 0), 1., , 2., , 3., , For the myopic eye, the defect is cured by, (a) Convex lens, (b) Concave lens, (c) Cylindrical lens, (d) Toric lens, A person cannot see distinctly at the distance less, than one metre. Calculate the power of the lens that, he should use to read a book at a distance of 25 cm, (a) + 3.0 D, (b) + 0.125 D, (c) – 3.0 D, (d) + 4.0 D, A man who cannot see clearly beyond 5 m wants to, see stars clearly. He should use a lens of focal, length, (a) – 100 m, (b) + 5 m, (c) – 5 m, (d) Very large, , 7., , 8., , 9., , A person cannot see objects clearly beyond 2.0 m., The power of lens required to correct his vision, will be, (a) + 2.0 D, (b) – 1.0 D, (c) + 1.0 D, (d) – 0.5 D, Near and far points of a human eye are, (a) 0 and 25 cm, (b) 0 and , (c) 25 cm and 100 cm (d) 25 cm and , If the distance of the far point for a myopia patient, is doubled, the focal length of the lens required to, cure it will become, (a) Half, (b) Double, (c) The same but a convex lens, (d) The same but a concave lens, A short sighted person can see distinctly only those, objects which lie between 10 cm and 100 cm from, him. The power of the spectacle lens required to, see a distant object is, (a) + 0.5 D, (b) – 1.0 D, (c) – 10 D, (d) + 4.0 D, A person wears glasses of power – 2.5 D. The, defect of the eye and the far point of the person, without the glasses are respectively, (a) Farsightedness, 40 cm, (b) Nearsightedness, 40 cm, (c) Astigmatism, 40 cm, (d) Nearsightedness, 250 cm, A defective eye cannot see close objects clearly, because their image is formed, (a) On the eye lens, , page- 18 -
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(b) Between eye lens and retina, (c) On the retina, (d) Beyond retina, , Microscope & telescope, 15., , 16., , 17., , Single choice questions (Level 0), 10., , 11., , 12., , 13., , 14., , Amount of light entering into the camera depends, upon, (a) Focal length of the objective lens, (b) Product of focal length and diameter of the, objective lens, (c) Distance of the object from camera, (d) Aperture setting of the camera, The light gathering power of a camera lens, depends on, (a) Its diameter only, (b) Ratio of focal length and diameter, (c) Product of focal length and diameter, (d) Wavelength of light used, The focal length of the objective lens of a, compound microscope is, (a) Equal to the focal length of its eye piece, (b) Less than the focal length of eye piece, (c) Greater than the focal length of eye piece, (d) Any of the above three, Least distance of distinct vision is 25 cm., Magnifying power of simple microscope of focal, length 5 cm is, (a) 1 / 5, (b) 5, (c) 1 / 6, (d) 6, A photograph of the moon was taken with, telescope. Later on, it was found that a housefly, was sitting on the objective lens of the telescope. In, photograph, , 18., , 19., , 20., , 21., , (a) The image of housefly will be reduced, (b) There is a reduction in the intensity of the, image, (c) There is an increase in the intensity of the, image, (d) The image of the housefly will be enlarged, For a telescope to have large resolving power the, (a) Focal length of its objective should be large, (b) Focal length of its eye piece should be large, (c) Focal length of its eye piece should be small, (d) Aperture of its objective should be large, The focal length of objective and eye lens of a, astronomical telescope are respectively 2 m and 5, cm. Final image is formed at (i) least distance of, distinct vision (ii) infinity. The magnifying power, in both cases will be, (a) – 48, – 40, (b) – 40, – 48, (c) – 40, 48, (d) – 48, 40, To increase the magnifying power of telescope (fo, = focal length of the objective and fe = focal length, of the eye lens), (a) fo should be large and fe should be small, (b) fo should be small and fe should be large, (c) fo and fe both should be large, (d) fo and fe both should be small, An astronomical telescope has an angular, magnification of magnitude 5 for distant objects., The separation between the objective and the eye, piece is 36 cm and the final image is formed at, infinity. The focal length fo of the objective and the, focal length fe of the eye piece are, (a) fo = 45 cm and fe = – 9 cm, (b) fo = 7.2 cm and fe = 5 cm, (c) fo = 50 cm and fe = 10 cm, (d) fo = 30 cm and fe = 6 cm, The length of an astronomical telescope for normal, vision (relaxed eye) (fo = focal length of objective, lens and fe = focal length of eye lens) is, fo, fe, , (a) fo fe, , (b), , (c) fo fe, , (d) fo fe, , The focal lengths of the objective and eye-piece of, a telescope are respectively 100 cm and 2 cm. The, moon subtends an angle of 0.5 o at the eye. If it is, looked through the telescope, the angle subtended, by the moon's image will be, (a) 100 o, (b) 50 o, o, (c) 25, (d) 10 o, The resolving power of a telescope depends on, (a) Focal length of eye lens, (b) Focal length of objective lens, (c) Length of the telescope, (d) Diameter of the objective lens, , page- 19 -
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22., , 23., , A Galileo telescope has an objective of focal length, 100cm and magnifying power 50. The distance, between the two lenses in normal adjustment will, be, (a) 96 cm, (b) 98 cm, (c) 102 cm, (d) 104 cm, If in compound microscope m1 and m2 be the linear, magnification of the objective lens and eye lens, respectively, then magnifying power of the, compound microscope will be, , m1 m 2, , (a) m 1 m 2, , (b), , (c) (m 1 m 2 ) / 2, , (d) m 1 m 2, , DISPERSION OF LIGHT:, PROBLEMS & OVERVIEW, , (c), , Single choice questions (Level 0), 1., , 2., , 3., , Which of the following is not a correct statement, (a) The wavelength of red light is greater than the, wavelength of green light, (b) The wavelength of blue light is smaller than the, wavelength of orange light, (c) The frequency of green light is greater than the, frequency of blue light, (d) The frequency of violet light is greater than the, frequency of blue light, A plane glass slab is kept over various coloured, letters, the letter which appears least raised is, (a) Blue, (b) Violet, (c) Green, (d) Red, Formula for dispersive power is (where symbols, have their usual meanings), Or, If the refractive indices of crown glass for red,, yellow and violet colours are respectively r , y, and v , then the dispersive power of this glass, would be, , (a) v y, r 1, , (b), , v r, y 1, , 4., , 5., , 6., , v y, y r, , (d), , v r, 1, y, , If the refractive indices of crown glass for red,, yellow and violet colours are 1.5140, 1.5170 and, 1.5318 respectively and for flint glass these are, 1.6434, 1.6499 and 1.6852 respectively, then the, dispersive powers for crown and flint glass are, respectively, (a) 0.034 and 0.064, (b) 0.064 and 0.034, (c) 1.00 and 0.064, (d) 0.034 and 1.0, If the refractive indices of a prism for red, yellow, and violet colours be 1.61, 1.63 and 1.65, respectively, then the dispersive power of the prism, will be, (a), , 1 .65 1 .62, 1 .61 1, , (b), , 1 .62 1 .61, 1 .65 1, , (c), , 1 .65 1 .61, 1 .63 1, , (d), , 1 .65 1 .63, 1 .61 1, , Which of the following diagrams, shows correctly, the dispersion of white light by a prism, (a), , V, , (b), , V, R, , R, , page- 20 -
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(c), , (d), , V, , R, V, , 7., , 8., , 9., , 10., , Which of the following colours suffers maximum, deviation in a prism, (a) Yellow, (b) Blue, (c) Green, (d) Orange, If the refractive angles of two prisms made of, crown glass are 10o and 20o respectively, then the, ratio of their colour deviation powers will be, (a) 1 : 1, (b) 2 : 1, (c) 4 : 1, (d) 1 : 2, The refractive index of a piece of transparent, quartz is the greatest for, (a) Red light, (b) Violet light, (c) Green light, (d) Yellow light, With respect to air critical angle in a medium for, light of red colour [1 ] is . Other facts remaining, same, critical angle for light of yellow colour [2 ], will be, (a) , (b) More than , (c) Less than , , 11., , 13., , 14., , R, , (d), , 1, 2, , White light is incident on, the interface of glass and, air as shown in the Air, figure. If green light is Glass, just totally internally, reflected, then, the, emerging ray in air, contains, (a) Yellow, orange, red, (b) Violet, indigo, blue, (c) All colours, (d) All colours except green, , Green, , White, , White light is passed through a prism whose angle, is 5°. If the refractive indices for rays of red and, blue colour are respectively 1.64 and 1.66, the, angle of deviation between the two colours will be, (a) 0.1 degree, (b) 0.2 degree, (c) 0.3 degree, (d) 0.4 degree, For a medium, refractive indices for violet, red and, yellow are 1.62, 1.52 and 1.55 respectively, then, dispersive power of medium will be, , (a) 0.65, (b) 0.22, (c) 0.18, (d) 0.02, 15. The refractive indices for the light of violet and red, colours of any material are 1.66 and 1.64, respectively. If the angle of prism made of this, material is 10o, then angular dispersion will be, (a) 0.20o, (b) 0.10o, (c) 0.40o, (d) 1o, 16. The deviation caused in red, yellow and violet, colours for crown glass prism are 2.84o, 3.28o and, 3.72o respectively. The dispersive power of prism, material is, (a) 0.268, (b) 0.368, (c) 0.468, (d) 0.568, 17. Dispersion of light is due to, (a) Wavelength, (b) Intensity of light, (c) Density of medium (d) None of these, 18. When white light enters a prism, it gets split into, its constituent colours. This is due to, (a) High density of prism material, (b) Because is different for different , (c) Diffraction of light, (d) Velocity changes for different frequencies, 19. A thin prism P1 with angle 4° and made from glass, of refractive index 1.54 is combined with another, thin prism P2 made from glass of refractive index, 1.72 to produce dispersion without deviation. The, angle of prism P2 is, (a) 2.6°, (b) 3°, (c) 4°, (d) 5.33°, 20. If the red light is replaced by blue light, illuminating the object in a microscope the, resolving power of the microscope, (a) Decreases, (b) Increases, (c) Gets halved, (d) Remains unchanged, 21. A thin prism P1 with angle 40 and made from glass, of refractive index 1.54 is combined with another thin, prism P2 made from glass of refractive index 1.72 to, produce dispersion without deviation. The angle of, the prism P2 is, (a) 5.330, (b) 40, (c) 30, (d) 2.60, , …By praveen gupta, , page- 21 -
