Ray Optics PYQs Set 5 (PDF)

Set 5 of 16 · Questions 121-150 of 467

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Mere Teacher · Previous Year Questions NEET Physics · Ray Optics · Set 5 (Q121-150)
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121. $A girl of height 150 cm with her eye level at 140 cm stands in front of plane mirror of height 75 cm fixed to a wall. The lower edge of the mirror is at a height of 85 cm above her feet level. The height of her image the girl can see in the mirror is$ (1) $130 cm$ (2) $140 cm$ (3) $120 cm$ (4) $150 cm$ 122. $A screen is placed 90 cm from an object. The image is formed by using a convex lens twice on the screen by putting the lens at two different locations separated by 20 cm . The focal length of the lens is approximately equal to$ (1) $21.38 cm$ (2) $30.0 cm$ (3) $35.0 cm$ (4) $24 cm$ 123. $In total internal reflection when the angle ofincidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction7.$ (1) $9 0^{o}$ (2) $18 0^{o}$ (3) $0^{o}$ (4) $equal to angle of incidence$ 124. $The radius of curvature of a convex lens is , for each surface. Its refractive index is 1.5 . Its focal length is$ (1) $40 cm$ (2) $20 cm$ (3) $80 cm$ (4) $30 cm$ 125. $An equiconvex lens made of glass of refractive index has focal length in air. It is completely immersed in water of refractive index . The percentage change in the focal length is$ (1) $400 % increase$ (2) $300 % decrease$ (3) $400 % decrease$ (4) $300 % increase$ 126. $A linear object of height 10 cm is kept in front of a concave mirror of radius of curvature 15 cm, at a distance of 10 cm . The image formed is$ (1) $magnified and erect$ (2) $magnified and inverted$ (3) $diminished and erect$ (4) $diminished and inverted.$ 127. $Which one of the following phenomena is not explained by Huygen’s construction of wavefront?.$ (1) $Refraction$ (2) $Reflection$ (3) $Diffraction$ (4) $Origin ofspectra$ 128. $Two convex lenses of focal lengths f_{1} and f_{2} form images with magnification m_{1} and m_{2}, when used individually for an object kept at the same distance from the lenses. Then, f_{1} / f_{2} is$ (1) $\frac{m _{1} ( 1 - m _{1} )}{m _{2} ( 1 - m _{2} )}$ (2) $\frac{m _{1} ( 1 - m _{2} )}{m _{2} ( 1 - m _{1} )}$ (3) $\frac{m _{2} ( 1 - m _{1} )}{m _{1} ( 1 - m _{2} )}$ (4) $\frac{m _{2} ( 1 - m _{2} )}{m _{1} ( 1 - m _{1} )}$ 129. $Which of the following is not due to total internal reflection?.$ (1) $Working of optical fibre$ (2) $Difference between apparent and real depth of a pond$ (3) $Mirage on hot summer days$ (4) $Brilliance of diamond$ 130. $According to Newton's corpuscular theory the speed of light is$ (1) $same in all the media$ (2) $lesser in rarer medium$ (3) $lesser in denser medium$ (4) $independent of the medium.$ 131. $The angle of minimum deviation for an incident light ray on an equilateral prism is equal to its refracting angle. The refractive index of its material is$ (1) $\frac{1}{2}$ (2) $3$ (3) $\frac{3}{2}$ (4) $\frac{3}{2}$ 132. $A convex lens of focal length 30 cm is placed in contact with a concave lens of focal length 20 cm. An object is placed at 20 cm to the left of this lens system. The distance of the image from the lens in cm is _______.$ (1) $\frac{60}{7}$ (2) $15$ (3) $45$ (4) $30$ 133. $A ray of light is incident at an angle of incidence, i, on one face of prism of angle A (assumed to be small) and emerges normally from the opposite face. If the refractive index of the prism is μ, the angle of incidence i, is nearly equal to :$ (1) $μA$ (2) $A/3μ$ (3) $A/μ$ (4) $A/2μ$ 134. $Pick out the WRONG statement from the following.$ (1) $Lateral shift increases as the angle of incidence increases.$ (2) $Lateral shift increases as the value of refractive index increases.$ (3) $Normal shift decreases as the value of refractive index increases.$ (4) $Both normal shift and lateral shift are directly proportional to the thickness of the medium.$ 135. $An object is placed at 20 cm in front of a concave mirror produces three times magnified real image. What is focal length of the concave mirror?$ (1) $10 cm$ (2) $15 cm$ (3) $7.5 cm$ (4) $6.6 cm$ 136. $The power of a biconvex lens is 10 D and the radius of curvature of each surface is 10 cm . Then, the refractive index of the material of the lens is [NEET 2020]$ (1) $\frac{4}{3}$ (2) $\frac{9}{8}$ (3) $\frac{5}{3}$ (4) $\frac{3}{2}$ 137. $The reddish appearance of the sun at sunrise and sunset is due to$ (1) $the scattering oflight$ (2) $the polarisation oflight$ (3) $the colour of the sun$ (4) $the colour of the sky.$ 138. $Two thin lenses are of same focal lengths (f), but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be [NEET 2023]$ (1) $f/4$ (2) $f/2$ (3) $infinite$ (4) $Zero$ 139. $A concave mirror of focal length in air is dipped in a liquid of refractive index . Its focallength in the liquid will be:$ (1) $μf$ (2) $f$ (3) $\frac{f}{( μ - 1 )}$ (4) $\frac{f}{μ}$ 140. $The focal length of biconvex lens made of glass, of equal radii is . If the lens is dipped in the water, then the focal length becomes (Take, refractive index of glass and water as and , respectively)$ (1) $2 f$ (2) $4 f$ (3) $(5/3) f$ (4) $(7/4)f$ 141. $Consider an equilateral prism (refractive index ). A ray of light is incident on its one surface at a certain angle . If the emergent ray is found to graze along the other surface then the angle of refraction at the incident surface is close to .$ (1) $20^{\circ}$ (2) $15^{\circ}$ (3) $40^{\circ}$ (4) $30^{\circ}$ 142. $White light is incident normally on a glass slab. Inside the glass slab,$ (1) $red light travels faster than other colours$ (2) $violet light travels faster than other colours$ (3) $yellow light travels faster than other colours$ (4) $all colours travel with the same speed.$ 143. $A lens having refractive index 1.6 has focal length of 12 cm, when it is in air. Find the focal length of the lens when it is placed in water. (Take refractive index of water as 1.28)$ (1) $355 mm$ (2) $655 mm$ (3) $288 mm$ (4) $555 mm$ 144. $Two thin lenses have a combined power of + 9 D . When they are separated by a distance of 20 cm, their equivalent power becomes + \frac{27}{5} D . Their individual powers (in dioptres) are$ (1) $1,8$ (2) $2,7$ (3) $3,6$ (4) $4,5$ 145. $A convex lens of focal length 20 cm produces images of the same magnification 2 when an object is kept at two distances x_{1} and x_{2} (x_{1} > x_{2}) from the lens. The ratio of x_{1} and x_{2} is:$ (1) $2 : 1$ (2) $3 : 1$ (3) $5 : 3$ (4) $4 : 3$ 146. $During scattering of light, the amount of scattering is inversely proportional to of wavelength of light.$ (1) $square$ (2) $half$ (3) $cube$ (4) $fourth power$ 147. $White light is incident on one of the refracting surfaces of a prism of angle . If the refractive indices for red and blue colours are 1.641 and 1.659 respectively, the angular separation between these two colours when they emerge out of the prism is$ (1) $0.9^{\circ}$ (2) $0.09^{\circ}$ (3) $1.8^{\circ}$ (4) $1.2^{\circ}$ 148. $Wavelength of given light waves in air and in a medium are 6000Å and 4000Å respectively. The critical angle is$ (1) $tan^{- 1} (\frac{2}{3})$ (2) $tan^{- 1} (\frac{3}{2})$ (3) $sin^{- 1} (\frac{2}{3})$ (4) $sin^{- 1} (\frac{3}{2})$ 149. $A linear aperture whose width is 0.02 cm is placed immediately in front of a lens of focal length 60 cm. The aperture is illuminated normally by a parallel beam of wavelength cm. The distance of the first dark band of the diffraction pattern from the centre of the screen is$ (1) $0.10 cm$ (2) $0.25 cm$ (3) $0.20 cm$ (4) $0.15 cm.$ 150. $A person uses a lens of power + 3D to normalise vision. Near point of hypermetropic eye is$ (1) $1 m$ (2) $1.66 m$ (3) $2 m$ (4) $0.66 m$