Ray Optics PYQs Set 4 (PDF)

Set 4 of 16 · Questions 91-120 of 467

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Mere Teacher · Previous Year Questions NEET Physics · Ray Optics · Set 4 (Q91-120)
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91. $If the image of an object is at the focal point f to the right side of a convex lens, the position of the object on the left of the lens is at$ (1) $f$ (2) $2 f$ (3) $< f$ (4) $\infty$ 92. $The power of an equi-concave lens is and is made of a material of refractive index 1.6 , the radii of curvature of the lens is$ (1) $- 2.66 cm$ (2) $- 26.6 cm$ (3) $+ 115.44 cm$ (4) $+ 36.6 cm$ 93. $Different objects at different distances are seen by the eye. The parameter that remains constant is :$ (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) $The image distance from the eye lens$ 94. $The size of the image of an object, which is at infinity, as formed by a convex lens of focal length 30 cm is 2 cm . If a concave lens of focal length 20 cm is placed between the convex lens and the image at a distance of 26 cm from the lens, the new size of the image is$ (1) $1.25 cm$ (2) $2.5 cm$ (3) $1.05 cm$ (4) $2 cm$ 95. $A biconvex lens of refractive index 1.5 has a focal length of in air. Its focal length when immersed in a liquid of refractive index 1.6 will be:$ (1) $- 16 cm$ (2) $- 160 cm$ (3) $+ 160 cm$ (4) $+ 16 cm$ 96. $Focal length of convex lens in air is . Now the lens is submerged in liquid of refractive index . Find the ratio of focal length in medium to focal length in air has closest value$ (1) $9$ (2) $17$ (3) $1$ (4) $5$ 97. $A transparent glass cube of length 24 cm has a small air bubble trapped inside. When seen normally through one surface from air outside, its apparent distance is 10 cm from the surface. When seen normally from opposite surface, its apparent distance is 6 cm . The distance of the air bubble from first surface is$ (1) $15 cm$ (2) $14 cm$ (3) $12 cm$ (4) $8 cm$ 98. $A bi-convex lens has radius of curvature of both the surfaces same as 1/6 cm . If this lens is required to be replaced by another convex lens having different radii of curvatures on both sides (R_{1} \neq = R_{2}), without any change in lens power then possible combination of R_{1} and R_{2} is:$ (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) $\frac{1}{6} cm and \frac{1}{9} cm$ 99. $For the myopic eye, the defect is cured by$ (1) $Convex lens$ (2) $Concave lens$ (3) $Cylindrical lens$ (4) $Toric lens$ 100. $The magnitudes of power of a biconvex lens (refractive index 1.5) and that of a plano-concave lens (refractive index ) are same. If the curvature of planoconcave lens exactly matches with the curvature of back surface of the biconvex lens, then ratio of radius of curvature of front and back surface of the biconvex lens is .$ (1) $5 : 12$ (2) $12 : 5$ (3) $5 : 2$ (4) $2 : 5$ 101. $Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason RAssertion A: The phase difference of two light waves change if they travel through different media having same thickness, but different indices of refraction.Reason R: The wavelengths of waves are different in different media.In the light of the above statements, choose the most appropriate answer from the options given below$ (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) $Both A and R are correct and R is the correct explanation of A$ 102. $What minimum separation between two objects a human eye would be able to resolve, if the eye pupil diameter is 2 mm and the two objects are 20 m away from the eye? (Assume, human eye to be equivalent to a convex lens and consider-the average wave length of light as 600 nm)$ (1) $7.32 mm$ (2) $8.72 mm$ (3) $6.2 mm$ (4) $4.71 mm$ 103. $In Young’s double slit experiment, the slits are 2 mm apart and are illuminated by photons of two wavelengths λ_{1} = 12000 A^{\circ} and λ_{2} = 10000 A^{\circ} . At what minimum distance from the common central bright fringe on the screen 2 m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other7.$ (1) $4 mm$ (2) $3 m$ (3) $8 mm$ (4) $6 mm$ 104. $The refracting angle of a glass prism is . A ray is incident on one of the faces perpendicular to it. The angle of deviation between the incident ray and that leaves the prism is (Refractive index of glass )$ (1) $17^{\circ}$ (2) $18.6^{\circ}$ (3) $12.6^{\circ}$ (4) $16^{\circ}$ 105. $A thin prism with an angle 6° and made of glass of refractive index 1.54 is combined with another prism made from glass of refractive index 1.72 to produce dispersion without average deviation. The angle of prism is :$ (1) $6°$ (2) $1. 3^{0}$ (3) $7. 8^{0}$ (4) $4. 5^{0}$ 106. $A boat has green light of wavelength λ = 500 nm on the mast. What wavelength would be measured and what colour would be observed for this light as seen by a diver submerged in water by the side of the boat? Given n_{w} = \frac{4}{3} .$ (1) $Green of wavelength 376 nm$ (2) $Red of wavelength 665 nm$ (3) $Green of wavelength 500 nm$ (4) $Blue of wavelength 376 nm$ 107. $Distance between an object and three times magnified real image is 40 cm . The focal length of the mirror used is____cm.$ (1) $- 15/2$ (2) $-15$ (3) $-10$ (4) $-20$ 108. $A point object is moving at a constant speed of 1 m s^{- 1} along the principal axis of a conver lens of focal length 10 cm . The speed of the image is also 1 m s^{- 1}, when the object is at cm from the optic centre of the lens.$ (1) $10$ (2) $15$ (3) $20$ (4) $5$ 109. $A person cannot see distinctly at the distance less than one metre. Calculate the power of the lens that he should use to read a book at a distance of 25 cm$ (1) $+ 3.0 D$ (2) $+ 0.125 D$ (3) $- 3.0 D$ (4) $+ 4.0 D$ 110. $Two thin lenses of focal lengths f_{1} and f_{2} are in contact and coaxial. The power of the combination is$ (1) $\frac{f _{1} + f _{2}}{2}$ (2) $\frac{f _{1} + f _{2}}{f _{1} f _{2}}$ (3) $\frac{f _{1}}{f _{2}}$ (4) $.$ 111. $A convex lens forms a real image of a point object placed on its principal axis. If the upper half of the lens is painted black, then$ (1) $the image shifts upward$ (2) $the image shifts downward$ (3) $the intensity of the image decreases$ (4) $the intensity of the image increases$ 112. $An object is at a distance of 20 m from a convex lens of focal length 0.3 m . The lens forms an image of the object. If the object moves away from the lens at a speed of 5 m / s, the speed and direction of the image will be:$ (1) $2.26 \times 10^{- 3} m / s away from the lens$ (2) $0.92 \times 10^{- 3} m / s away from the lens$ (3) $3.22 \times 10^{- 3} m / s towards the lens$ (4) $1.16 \times 10^{- 3} m / s towards the lens$ 113. $A ray of light suffers a minimum deviation when incident on an equilateral prism of refractive index . The angle of incidence is$ (1) $30^{\circ}$ (2) $45^{\circ}$ (3) $60^{\circ}$ (4) $50^{\circ}$ 114. $A double convex lens has power P and same radii of curvature R of both the surfaces. The radius of curvature of a surface of a planoconvex lens made of the same material with power 1.5 P is$ (1) $\frac{3 R}{2}$ (2) $2 R$ (3) $\frac{R}{3}$ (4) $\frac{R}{2}$ 115. $A parallel beam of light of wavelength is incident normally on a narrow slit. A diffraction pattern formed on a screen placed perpendicular to the direction ofthe incident beam. At the second minimum of the diffraction pattern, the phase difference between the rays coming from the two edges of slit is$ (1) $2 π$ (2) $3 π$ (3) $4 π$ (4) $π λ .$ 116. $For the thin convex lens, the radii of curvature are at 15 cm and 30 cm respectively. The focal length the lens is 20 cm. The refractive index of the material is :$ (1) $1.2$ (2) $1.8$ (3) $1.5$ (4) $1.4$ 117. $For a concave mirror of focal length 20 cm, If the object is at a distance of 30 cm from the pole, the nature of image and magnification will be-$ (1) $Real and - 2$ (2) $Virtual and - 2$ (3) $Real and + 2$ (4) $Virtual and + 2$ 118. $A person can see clearly objects only when they lie between 50 cm and 400 cm from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use, will be$ (1) $convex, + 2.25 dioptre$ (2) $concave, - 0.25 dioptre$ (3) $concave, - 0.2 dioptre$ (4) $convex, + 0.15 dioptre.$ 119. $Refractive index of a medium is . If the angle of incidence is twice that of the angle of refraction, then the angle of incidence is$ (1) $cos^{- 1} (\frac{μ}{2})$ (2) $sin^{- 1} (\frac{μ}{2})$ (3) $2 cos^{- 1} (\frac{μ}{2})$ (4) $sin^{- 1} (μ)$ 120. $Which of the following statement is correct ?$ (1) $In primary rainbow, observer sees red colour on the top and violet on the bottom$ (2) $In primary rainbow, observer sees violet colour on the top and red on the bottom$ (3) $In primary rainbow, light wave suffers total internal reflection twice before coming out of water drops$ (4) $Primary rainbow is less bright than secondary rainbow.$