Ray Optics PYQs Set 2 (PDF)

Set 2 of 18 · Questions 31-60 of 521

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Mere Teacher · Previous Year Questions JEE Main Physics · Ray Optics · Set 2 (Q31-60)
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31. $A double convex lens has focal length 25 cm. The radius of curvature of one of the surfaces is doubled of the other. Find the radii, if the refractive index of the material of the lens is 1.5. [NEET 2019]$ (1) $100 cm, 50 cm$ (2) $25 cm, 50 cm$ (3) $18.75 cm, 37.5 cm$ (4) $50 cm, 100 cm$ 32. $An object is placed infront of a convex lens of focal length made of a material of refractive index 1.5 . The surface of the lens away from the object is silvered. If the radius of curvature of the silvered surface is 22 , then the distance of the final image from the silvered surface is$ (1) $10 cm$ (2) $11 cm$ (3) $12 cm$ (4) $13 cm$ 33. $The radii of curvature for a thin convex lens are 10 cm and 15 cm respectively. The focal length of the lens is 12 cm. The refractive index of the lens material is$ (1) $1.4$ (2) $1.8$ (3) $1.5$ (4) $1.2$ 34. $An equiconvex lens has power P It is cut into two symmetrical halves by a plane containing the principal axis. The power of one part will be$ (1) $0$ (2) $\frac{P}{2}$ (3) $\frac{P}{4}$ (4) $P$ 35. $Your friend is having eye sight problem. She is not able lo see clearly a distant uniform window mesh and itappears to her as nonuniform and distorted. The doctor diagnosed the problem as:$ (1) $Astigmatism$ (2) $Myopia with Astigmatism$ (3) $Presbyopia with Astigmatism$ (4) $Myopia and hypermetropia$ 36. $The distance of distinct vision of a person is 50 cm. He wants to read a book placed at 25 cm. What should be the focal length of the spectacles?$ (1) $25 cm$ (2) $50 cm$ (3) $75 cm$ (4) $100 cm$ 37. $A thin prism having refracting angle 10º is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be$ (1) $4º$ (2) $6º$ (3) $8º$ (4) $10º$ 38. $A thin prism with angle of refractive index 1.72 is combined with another prism of refractive index 1.9 to produce dispersion without deviation. The angle of second prism is .$ (1) $6^{\circ}$ (2) $4.5^{\circ}$ (3) $4^{\circ}$ (4) $5^{\circ}$ 39. $The rays of different colours fail to converge at a point after passing through a thick converging lens. The defect is called$ (1) $spherical aberration$ (2) $distortion$ (3) $coma aberration.$ (4) $chromatic$ 40. $Two point white dots are I mm apart on a black paper. They are viewed by eye of pupil diameter 3 mm. Approximately, what is the maximum distance at which these dots can be resolved by the eye? (Take wavelength of light= 500nm).$ (1) $5 m$ (2) $1 m$ (3) $6 m$ (4) $3 m$ 41. $Two thin biconvex lenses have focal lengths f_{1} and f_{2} . A third thin biconcave lens has focal length of f_{3} . If the two biconvex lenses are in contact, the total power of the lenses is P_{I} . If the first convex lens is in contact with the third lens, the total power is P_{2} . If the second lens is in contact with the third lens, the total power is P_{3} then$ (1) $P_{1} = \frac{f _{1} f _{2}}{f _{1} - f _{2}}, P_{2} = \frac{f _{1} f _{3}}{f _{3} - f _{1}} and P_{3} = \frac{f _{2} f _{3}}{f _{3} - f _{2}}$ (2) $P_{1} = \frac{f _{1} - f _{2}}{f _{1} f _{2}}, P_{2} = \frac{f _{3} - f _{1}}{f _{3} + f _{1}} and P_{3} = \frac{f _{3} - f _{2}}{f _{2} f _{3}}$ (3) $P_{1} = \frac{f _{1} - f _{2}}{f _{1} f _{2}}, P_{2} = \frac{f _{3} - f _{1}}{f _{1} f _{3}} and P_{3} = \frac{f _{3} - f _{2}}{f _{2} f _{3}}$ (4) $P_{1} = \frac{f _{1} + f _{2}}{f _{1} f _{2}}, P_{2} = \frac{f _{3} - f _{1}}{f _{1} f _{3}} and P_{3} = \frac{f _{3} - f _{2}}{f _{2} f _{3}}$ 42. $Refractive index of a glass convex lens is 1.5. The radius of curvature of each of the two surfaces of the lens is . The ratio of the power of the lens when immersed in a liquid of refractive index 1.25 to that when placed in air is$ (1) $2 : 3$ (2) $2 : 5$ (3) $3 : 2$ (4) $5 : 2$ 43. $In a Young’ double slit experiment if there is no initial phase difference between the light from the two slits, a point on the screen corresponding to the fifth minimum has path difference.$ (1) $5 \frac{λ}{2}$ (2) $10 \frac{λ}{2}$ (3) $9 \frac{λ}{2}$ (4) $11 \frac{λ}{2}$ 44. $With respect to air, the critical angle in a medium for red light of wave length λ_{1} is θ . Other facts remaining same, critical angle for yellow light of wave length λ_{2} will be$ (1) $θ$ (2) $more than θ$ (3) $less than θ$ (4) $\frac{θ λ _{1}}{λ _{2}}$ 45. $A mirror is used to produce an image with magnification of \frac{1}{4} . If the distance between object and its image is 40 cm, then the focal length of the mirror is ______$ (1) $10 cm$ (2) $12.7 cm$ (3) $10.7 cm$ (4) $15 cm$ 46. $Which colour of the light has the longest wavelength?.$ (1) $violet$ (2) $red$ (3) $blue$ (4) $green$ 47. $The light rays from an object have been reflected towards an observer from a standard flat mirror, the image observed by the observer are :- A. Real B. Erect C. Smaller in size then object D. Laterally inverted Choose the most appropriate answer from the options given below :$ (1) $B and D only$ (2) $B and C only$ (3) $A and D only$ (4) $A, C and D only$ 48. $The critical angle of a medium for a specific wavelength, if the medium has relative permittivity 3 and relative permeability \frac{4}{3} for this wavelength, will be:$ (1) $45^{\circ}$ (2) $60^{o}$ (3) $30^{o}$ (4) $15^{o}$ 49. $A person suffering from 'presbyopia' (myopia and hyper metropia both defects) should use$ (1) $A concave lens$ (2) $A convex lens$ (3) $A bifocal lens whose lower portion is convex$ (4) $A bifocal lens whose upper portion is convex$ 50. $A convex and a concave lens separated by distance d are then put in contact. The focal length of the combination$ (1) $becomes zero$ (2) $remains the same$ (3) $decreases$ (4) $increases.$ 51. $The refracting angle of a prism is A, and refractive index of the material of the prism is . The angle of minimum deviation is$ (1) $180^{\circ} - 3 A$ (2) $180^{\circ} - 2 A$ (3) $90^{\circ} - A$ (4) $180^{\circ} + 2 A$ 52. $In refraction, light waves are bent on passing from one medium to second medium because, in the second medium$ (1) $frequency is different$ (2) $speed is different$ (3) $coefficient of elasticity is different$ (4) $amplitude is smaller.$ 53. $In a microscope of tube length 10 cm two convex lenses are arranged with focal length of 2 cm and 5 cm . Total magnification obtained with this system for normal adjustment is (5)^{k} . The value of k is____.$ (1) $3.5$ (2) $2$ (3) $4$ (4) $5$ 54. $An ice cube has a bubble inside. When viewed from one side the apparent distance of the bubble is 12 cm. When viewed from the opposite side, the apparent distance of the bubble is observed as 4 cm. If the side of the ice cube is 24 cm, the refractive index of the ice cube is$ (1) $\frac{3}{2}$ (2) $\frac{2}{3}$ (3) $\frac{6}{5}$ (4) $\frac{4}{3}$ 55. $The critical angle of a medium for a specific wavelength, if the medium has relative permittivity 3 and relative permeability \frac{4}{3} for this wavelength, will be:$ (1) $15º$ (2) $30º$ (3) $60º$ (4) $45º$ 56. $Two thin equiconvex lenses each of focal length 0.2 m are placed coaxially with their optic centres 0.5 m apart. Then the focal length of the combination is$ (1) $- 0.4 m$ (2) $0.4 m$ (3) $- 0.1 m$ (4) $0.1 m .$ 57. $What is the refractive index of the material of a double convex lens having radii of curvature of and and focal length of$ (1) $1.5$ (2) $2.0$ (3) $2.4$ (4) $2.6$ 58. $An object is placed on the principal axis of a concave mirror at a distance of 1.5 f ( f is the focal length). The image will be at [NEET 2020]$ (1) $-3f$ (2) $1.5 f$ (3) $- 1.5 f$ (4) $3f$ 59. $The same size images are formed by a convex lens when the object is placed at 20 cm or at 10 cm from thelens. The focal length of convex lens is____cm .$ 60. $The distance between object and its two times magnified real image as produced by a convex lens is 45 cm . The focal length of the lens used is _____cm .$