Ray Optics PYQs Set 4 (PDF)

Set 4 of 18 · Questions 91-120 of 521

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Mere Teacher · Previous Year Questions JEE Main Physics · Ray Optics · Set 4 (Q91-120)
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91. $A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle θ, the spot of the light is found to move through a distance y on the scale. The angle θ is given by [NEET 2017]$ (1) $\frac{y}{2 x}$ (2) $\frac{y}{x}$ (3) $\frac{x}{2 y}$ (4) $\frac{x}{y}$ 92. $Radii of curvature of a converging lens are in the ratio . Its focal length is and refractive index is 1.5 . Then its radii of curvature are respectively.$ (1) $9 cm and 18 cm$ (2) $6 cm and 12 cm$ (3) $3 cm and 6 cm$ (4) $4.5 cm and 9 cm$ 93. $Calculate the focal length of a reading glass of a person if his distance of distinct vision is 75 cm .$ (1) $37.5 cm$ (2) $100.4 cm$ (3) $25.6 cm$ (4) $75.2 cm$ 94. $The focal lengths of the objective and the eyepiece of a compound microscope are 2 cm and 3 cm respectively and the distance between them is 15 cm . The final image formed by the eyepiece is at infinity. The distances of the object and the image produced by the object from the objective lens are respectively ,$ (1) $2.4 cm, 12 cm$ (2) $2.4 cm, 15 cm$ (3) $2.3 cm, 12 cm$ (4) $2.3 cm, 3 cm$ 95. $Light travels a distance x in time t_{1} in air and 10x in time t_{2} in another denser medium. What is the critical angle for this medium? [NEET 2023]$ (1) $sin^{- 1} (\frac{10 t _{2}}{t _{1}})$ (2) $sin^{- 1} (\frac{t _{1}}{10 t _{2}})$ (3) $sin^{- 1} (\frac{10 t _{1}}{t _{2}})$ (4) $sin^{- 1} (\frac{t _{2}}{t _{1}})$ 96. $According to Cartesian sign convention, in ray optics$ (1) $all distances in the direction of incident ray are taken positive.$ (2) $all distances are taken negative$ (3) $all distances in the direction of incident ray are taken negative$ (4) $all distances are taken positive.$ 97. $A convex lens made of glass (refractive index ) has focal length 24 cm in air. When itis totally immersed in water (refractive index ), its focal length changes to$ (1) $24 cm$ (2) $96 cm$ (3) $48 cm$ (4) $72 cm$ 98. $A plane glass plate is placed over a various coloured letters (violet, green, yellow, red). The letter which appears to raised more is$ (1) $Red$ (2) $Yellow$ (3) $Green$ (4) $Violet$ 99. $Consider a light source placed at a distance of 1.5 m along the axis facing the convex side of a spherical mirror of radius of curvature 1 m . The position (s^{’}, nature and magnification (m) of the image are$ (1) $s^{’} = 0.375 m, virtual, upright, m=0.25$ (2) $s^{’} = 0.375 m, real, inverted, m=0.25$ (3) $s^{’} = 3.75 m, virtual, inverted, m=2.5$ (4) $s^{’} = 3.75 m, real, upright, m=2.5$ 100. $If the refractive index from air to glass is and that from air to water is , then the ratio of focal lengths of a glass lens in water and in air is$ (1) $1 : 2$ (2) $2 : 1$ (3) $1 : 4$ (4) $4 : 1$ 101. $If the image of an object is at the focal point f to the right side of a convex lens, the position of the object on the left of the lens is at$ (1) $f$ (2) $2 f$ (3) $< f$ (4) $\infty$ 102. $The power of an equi-concave lens is and is made of a material of refractive index 1.6 , the radii of curvature of the lens is$ (1) $- 2.66 cm$ (2) $- 26.6 cm$ (3) $+ 115.44 cm$ (4) $+ 36.6 cm$ 103. $Different objects at different distances are seen by the eye. The parameter that remains constant is :$ (1) $The focal length of the eye lens$ (2) $The object distance from the eye lens$ (3) $The radii of curvature of the eye lens$ (4) $The image distance from the eye lens$ 104. $The size of the image of an object, which is at infinity, as formed by a convex lens of focal length 30 cm is 2 cm . If a concave lens of focal length 20 cm is placed between the convex lens and the image at a distance of 26 cm from the lens, the new size of the image is$ (1) $1.25 cm$ (2) $2.5 cm$ (3) $1.05 cm$ (4) $2 cm$ 105. $A biconvex lens of refractive index 1.5 has a focal length of in air. Its focal length when immersed in a liquid of refractive index 1.6 will be:$ (1) $- 16 cm$ (2) $- 160 cm$ (3) $+ 160 cm$ (4) $+ 16 cm$ 106. $Focal length of convex lens in air is . Now the lens is submerged in liquid of refractive index . Find the ratio of focal length in medium to focal length in air has closest value$ (1) $9$ (2) $17$ (3) $1$ (4) $5$ 107. $A transparent glass cube of length 24 cm has a small air bubble trapped inside. When seen normally through one surface from air outside, its apparent distance is 10 cm from the surface. When seen normally from opposite surface, its apparent distance is 6 cm . The distance of the air bubble from first surface is$ (1) $15 cm$ (2) $14 cm$ (3) $12 cm$ (4) $8 cm$ 108. $A bi-convex lens has radius of curvature of both the surfaces same as 1/6 cm . If this lens is required to be replaced by another convex lens having different radii of curvatures on both sides (R_{1} \neq = R_{2}), without any change in lens power then possible combination of R_{1} and R_{2} is:$ (1) $\frac{1}{3} cm and \frac{1}{7} cm$ (2) $\frac{1}{5} cm and \frac{1}{7} cm$ (3) $\frac{1}{3} cm and \frac{1}{3} cm$ (4) $\frac{1}{6} cm and \frac{1}{9} cm$ 109. $For the myopic eye, the defect is cured by$ (1) $Convex lens$ (2) $Concave lens$ (3) $Cylindrical lens$ (4) $Toric lens$ 110. $The magnitudes of power of a biconvex lens (refractive index 1.5) and that of a plano-concave lens (refractive index ) are same. If the curvature of planoconcave lens exactly matches with the curvature of back surface of the biconvex lens, then ratio of radius of curvature of front and back surface of the biconvex lens is .$ (1) $5 : 12$ (2) $12 : 5$ (3) $5 : 2$ (4) $2 : 5$ 111. $Rays converging at a point behind a convex mirror are incident on the mirror. Image formed will be -$ (1) $Virtual$ (2) $Real$ (3) $Erect$ (4) $Inverted$ 112. $Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason RAssertion A: The phase difference of two light waves change if they travel through different media having same thickness, but different indices of refraction.Reason R: The wavelengths of waves are different in different media.In the light of the above statements, choose the most appropriate answer from the options given below$ (1) $Both A and R are correct but R is NOT the correct explanation of A$ (2) $A is not correct but R is correct$ (3) $A is correct but R is not correct$ (4) $Both A and R are correct and R is the correct explanation of A$ 113. $What minimum separation between two objects a human eye would be able to resolve, if the eye pupil diameter is 2 mm and the two objects are 20 m away from the eye? (Assume, human eye to be equivalent to a convex lens and consider-the average wave length of light as 600 nm)$ (1) $7.32 mm$ (2) $8.72 mm$ (3) $6.2 mm$ (4) $4.71 mm$ 114. $In Young’s double slit experiment, the slits are 2 mm apart and are illuminated by photons of two wavelengths λ_{1} = 12000 A^{\circ} and λ_{2} = 10000 A^{\circ} . At what minimum distance from the common central bright fringe on the screen 2 m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other7.$ (1) $4 mm$ (2) $3 m$ (3) $8 mm$ (4) $6 mm$ 115. $The refracting angle of a glass prism is . A ray is incident on one of the faces perpendicular to it. The angle of deviation between the incident ray and that leaves the prism is (Refractive index of glass )$ (1) $17^{\circ}$ (2) $18.6^{\circ}$ (3) $12.6^{\circ}$ (4) $16^{\circ}$ 116. $A thin prism with an angle 6° and made of glass of refractive index 1.54 is combined with another prism made from glass of refractive index 1.72 to produce dispersion without average deviation. The angle of prism is :$ (1) $6°$ (2) $1. 3^{0}$ (3) $7. 8^{0}$ (4) $4. 5^{0}$ 117. $A boat has green light of wavelength λ = 500 nm on the mast. What wavelength would be measured and what colour would be observed for this light as seen by a diver submerged in water by the side of the boat? Given n_{w} = \frac{4}{3} .$ (1) $Green of wavelength 376 nm$ (2) $Red of wavelength 665 nm$ (3) $Green of wavelength 500 nm$ (4) $Blue of wavelength 376 nm$ 118. $Distance between an object and three times magnified real image is 40 cm . The focal length of the mirror used is____cm.$ (1) $- 15/2$ (2) $-15$ (3) $-10$ (4) $-20$ 119. $A collimated beam of light of diameter 2 mm is propagating along x -axis. The beam is required to be expanded in a collimated beam of diameter 14 mm using a system of two convex lenses. If first lens has focal length 40 mm , then the focal length of second lens is____mm .$ 120. $A prism of angle has a refractive index . A good estimate for the minimum angle of deviation (in degrees) is close to . Value of is$