Ray Optics PYQs Set 6 (PDF)

Set 6 of 18 · Questions 151-180 of 521

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions JEE Main Physics · Ray Optics · Set 6 (Q151-180)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
151. $The power of a biconvex lens is 10 D and the radius of curvature of each surface is 10 cm . Then, the refractive index of the material of the lens is [NEET 2020]$ (1) $\frac{4}{3}$ (2) $\frac{9}{8}$ (3) $\frac{5}{3}$ (4) $\frac{3}{2}$ 152. $The reddish appearance of the sun at sunrise and sunset is due to$ (1) $the scattering oflight$ (2) $the polarisation oflight$ (3) $the colour of the sun$ (4) $the colour of the sky.$ 153. $Two thin lenses are of same focal lengths (f), but one is convex and the other one is concave. When they are placed in contact with each other, the equivalent focal length of the combination will be [NEET 2023]$ (1) $f/4$ (2) $f/2$ (3) $infinite$ (4) $Zero$ 154. $A concave mirror of focal length in air is dipped in a liquid of refractive index . Its focallength in the liquid will be:$ (1) $μf$ (2) $f$ (3) $\frac{f}{( μ - 1 )}$ (4) $\frac{f}{μ}$ 155. $The focal length of biconvex lens made of glass, of equal radii is . If the lens is dipped in the water, then the focal length becomes (Take, refractive index of glass and water as and , respectively)$ (1) $2 f$ (2) $4 f$ (3) $(5/3) f$ (4) $(7/4)f$ 156. $Consider an equilateral prism (refractive index ). A ray of light is incident on its one surface at a certain angle . If the emergent ray is found to graze along the other surface then the angle of refraction at the incident surface is close to .$ (1) $20^{\circ}$ (2) $15^{\circ}$ (3) $40^{\circ}$ (4) $30^{\circ}$ 157. $White light is incident normally on a glass slab. Inside the glass slab,$ (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) $all colours travel with the same speed.$ 158. $A lens having refractive index 1.6 has focal length of 12 cm, when it is in air. Find the focal length of the lens when it is placed in water. (Take refractive index of water as 1.28)$ (1) $355 mm$ (2) $655 mm$ (3) $288 mm$ (4) $555 mm$ 159. $Two thin lenses have a combined power of + 9 D . When they are separated by a distance of 20 cm, their equivalent power becomes + \frac{27}{5} D . Their individual powers (in dioptres) are$ (1) $1,8$ (2) $2,7$ (3) $3,6$ (4) $4,5$ 160. $A convex lens of focal length 20 cm produces images of the same magnification 2 when an object is kept at two distances x_{1} and x_{2} (x_{1} > x_{2}) from the lens. The ratio of x_{1} and x_{2} is:$ (1) $2 : 1$ (2) $3 : 1$ (3) $5 : 3$ (4) $4 : 3$ 161. $During scattering of light, the amount of scattering is inversely proportional to of wavelength of light.$ (1) $square$ (2) $half$ (3) $cube$ (4) $fourth power$ 162. $White light is incident on one of the refracting surfaces of a prism of angle . If the refractive indices for red and blue colours are 1.641 and 1.659 respectively, the angular separation between these two colours when they emerge out of the prism is$ (1) $0.9^{\circ}$ (2) $0.09^{\circ}$ (3) $1.8^{\circ}$ (4) $1.2^{\circ}$ 163. $Wavelength of given light waves in air and in a medium are 6000Å and 4000Å respectively. The critical angle is$ (1) $tan^{- 1} (\frac{2}{3})$ (2) $tan^{- 1} (\frac{3}{2})$ (3) $sin^{- 1} (\frac{2}{3})$ (4) $sin^{- 1} (\frac{3}{2})$ 164. $A linear aperture whose width is 0.02 cm is placed immediately in front of a lens of focal length 60 cm. The aperture is illuminated normally by a parallel beam of wavelength cm. The distance of the first dark band of the diffraction pattern from the centre of the screen is$ (1) $0.10 cm$ (2) $0.25 cm$ (3) $0.20 cm$ (4) $0.15 cm.$ 165. $A person uses a lens of power + 3D to normalise vision. Near point of hypermetropic eye is$ (1) $1 m$ (2) $1.66 m$ (3) $2 m$ (4) $0.66 m$ 166. $The refractive index of a converging lens is . What will be the focal length of this lens if it is placed in amedium of same refractive index (Assume the radii of curvature of the faces of lens are and respectively)$ (1) $1$ (2) $Infinite$ (3) $\frac{R _{1} R _{2}}{R _{1} - R _{2}}$ (4) $Zero$ 167. $An object is placed at a distance of 20 cm from the pole of a concave mirror of focal length 10 cm . The distance of the image formed is$ (1) $+ 20 cm$ (2) $+ 10 cm$ (3) $- 20 cm$ (4) $- 10 cm$ 168. $A person wears glasses of power - 2.5 D. The defect of the eye and the far point of the person without the glasses are respectively$ (1) $Farsightedness, 40 cm$ (2) $Nearsightedness, 40 cm$ (3) $Astigmatism, 40 cm$ (4) $Nearsightedness, 250 cm$ 169. $A monochromatic light is incident at a certain angle on anequilateral triangular prism and suffers minimum deviation.If the refractive index of the material of the prism is ,then the angle of incidence is:$ (1) $90^{\circ}$ (2) $30^{\circ}$ (3) $60^{\circ}$ (4) $45^{\circ}$ 170. $Two thin convex lenses of focal lengths 30 cm and 10 cm are placed coaxially, 10 cm apart. The power of this combination is:$ (1) $5 D$ (2) $1 D$ (3) $20 D$ (4) $10 D$ 171. $A person can see clearly object only when they lie between 50 cm and 400 cm from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use, will be :$ (1) $convex, +0.15 diopter$ (2) $convex, +2.25 diopter$ (3) $concave, -0.25 diopter$ (4) $concave, -0.2 diopter$ 172. $When a monochromatic ray of light is passed through an equilateral glass prism, it is found that the refracted ray in glass is parallel to the base of the prism. If and denote the angles of incidence and emergence respectively, then$ (1) $i > e$ (2) $i < e$ (3) $i = e$ (4) $i + e = 90^{\circ}$ 173. $A plano-convex lens (focal length , refractive index , radius of curvature ) fits exactly into a plano-concave lens (focal length refractive index radius of curvature ). Their plane surfaces are parallel to each other. Then, the focal length of the combination will be:$ (1) $f_{1} - f_{2}$ (2) $\frac{R}{μ _{2} - μ _{1}}$ (3) $2f1f2 f_{1} + f_{2}$ (4) $f_{1} + f_{2}$ 174. $A glass convex lens is of refractive index 1.55 with both faces of same radius of curvature. What is the radius of curvature required if focal length is to be ?$ (1) $18 cm$ (2) $21 cm$ (3) $20 cm$ (4) $22 cm$ 175. $A man can see the object between 15 cm and 30 cm. He uses the lens to see the far objects. Then due to the lens used, the near point will be at$ (1) $\frac{10}{3} cm$ (2) $30 cm$ (3) $15 cm$ (4) $\frac{100}{3} cm$ 176. $A thin prism with angle made of glass having refractive index 1.54, is combined withanother thin prism made of glass having refractive index 1.72 to get dispersion without deviation. The angle of the prism in degrees is$ (1) $3$ (2) $16/3$ (3) $4$ (4) $1.5$ 177. $A beam of light of nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 away. Thedistance between first dark fringes on either side of the central bright fringe is$ (1) $1.2 cm$ (2) $1.2 mm$ (3) $2.4 cm$ (4) $2.4 mm.$ 178. $Interference was observed in interference chamber where air was present, now the chamber is evacuated, and if the same light is used, a careful observer will see$ (1) $no interference$ (2) $interference with brighter bands$ (3) $interference with dark bands$ (4) $interference with larger width.$ 179. $A candle placed 25 cm from a lens forms an image on a screen placed 75 cm on the other side of the lens. The focal length and type of the lens should be$ (1) $+ 18.75 cm and convex lens$ (2) $- 18.75 cm and concave lens$ (3) $+ 20.25 cm and convex lens$ (4) $- 20.25 cm and concave lens$ 180. $A vessel of height is half-filled with a liquid of refractive index and the other half with a liquid of refractive index . (The given liquids are immiscible). Then the apparent depth of the inner surface of the bottom of the vessel (neglecting the thickness of the bottom of the vessel) will be$ (1) $\frac{n}{d ( n + 2 )}$ (2) $\frac{d ( n + 2 )}{n 2}$ (3) $\frac{2 n}{d ( n + 2 )}$ (4) $\frac{nd}{d + 2 n}$