Ray Optics PYQs Set 6 (PDF)

Set 6 of 16 · Questions 151-180 of 467

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Mere Teacher · Previous Year Questions NEET Physics · Ray Optics · Set 6 (Q151-180)
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151. $The refractive index of a converging lens is . What will be the focal length of this lens if it is placed in amedium of same refractive index (Assume the radii of curvature of the faces of lens are and respectively)$ (1) $1$ (2) $Infinite$ (3) $\frac{R _{1} R _{2}}{R _{1} - R _{2}}$ (4) $Zero$ 152. $An object is placed at a distance of 20 cm from the pole of a concave mirror of focal length 10 cm . The distance of the image formed is$ (1) $+ 20 cm$ (2) $+ 10 cm$ (3) $- 20 cm$ (4) $- 10 cm$ 153. $A person wears glasses of power - 2.5 D. The defect of the eye and the far point of the person without the glasses are respectively$ (1) $Farsightedness, 40 cm$ (2) $Nearsightedness, 40 cm$ (3) $Astigmatism, 40 cm$ (4) $Nearsightedness, 250 cm$ 154. $A monochromatic light is incident at a certain angle on anequilateral triangular prism and suffers minimum deviation.If the refractive index of the material of the prism is ,then the angle of incidence is:$ (1) $90^{\circ}$ (2) $30^{\circ}$ (3) $60^{\circ}$ (4) $45^{\circ}$ 155. $Two thin convex lenses of focal lengths 30 cm and 10 cm are placed coaxially, 10 cm apart. The power of this combination is:$ (1) $5 D$ (2) $1 D$ (3) $20 D$ (4) $10 D$ 156. $A person can see clearly object only when they lie between 50 cm and 400 cm from his eyes. In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use, will be :$ (1) $convex, +0.15 diopter$ (2) $convex, +2.25 diopter$ (3) $concave, -0.25 diopter$ (4) $concave, -0.2 diopter$ 157. $When a monochromatic ray of light is passed through an equilateral glass prism, it is found that the refracted ray in glass is parallel to the base of the prism. If and denote the angles of incidence and emergence respectively, then$ (1) $i > e$ (2) $i < e$ (3) $i = e$ (4) $i + e = 90^{\circ}$ 158. $A plano-convex lens (focal length , refractive index , radius of curvature ) fits exactly into a plano-concave lens (focal length refractive index radius of curvature ). Their plane surfaces are parallel to each other. Then, the focal length of the combination will be:$ (1) $f_{1} - f_{2}$ (2) $\frac{R}{μ _{2} - μ _{1}}$ (3) $2f1f2 f_{1} + f_{2}$ (4) $f_{1} + f_{2}$ 159. $A glass convex lens is of refractive index 1.55 with both faces of same radius of curvature. What is the radius of curvature required if focal length is to be ?$ (1) $18 cm$ (2) $21 cm$ (3) $20 cm$ (4) $22 cm$ 160. $A man can see the object between 15 cm and 30 cm. He uses the lens to see the far objects. Then due to the lens used, the near point will be at$ (1) $\frac{10}{3} cm$ (2) $30 cm$ (3) $15 cm$ (4) $\frac{100}{3} cm$ 161. $A thin prism with angle made of glass having refractive index 1.54, is combined withanother thin prism made of glass having refractive index 1.72 to get dispersion without deviation. The angle of the prism in degrees is$ (1) $3$ (2) $16/3$ (3) $4$ (4) $1.5$ 162. $A beam of light of nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 away. Thedistance between first dark fringes on either side of the central bright fringe is$ (1) $1.2 cm$ (2) $1.2 mm$ (3) $2.4 cm$ (4) $2.4 mm.$ 163. $Interference was observed in interference chamber where air was present, now the chamber is evacuated, and if the same light is used, a careful observer will see$ (1) $no interference$ (2) $interference with brighter bands$ (3) $interference with dark bands$ (4) $interference with larger width.$ 164. $A candle placed 25 cm from a lens forms an image on a screen placed 75 cm on the other side of the lens. The focal length and type of the lens should be$ (1) $+ 18.75 cm and convex lens$ (2) $- 18.75 cm and concave lens$ (3) $+ 20.25 cm and convex lens$ (4) $- 20.25 cm and concave lens$ 165. $A vessel of height is half-filled with a liquid of refractive index and the other half with a liquid of refractive index . (The given liquids are immiscible). Then the apparent depth of the inner surface of the bottom of the vessel (neglecting the thickness of the bottom of the vessel) will be$ (1) $\frac{n}{d ( n + 2 )}$ (2) $\frac{d ( n + 2 )}{n 2}$ (3) $\frac{2 n}{d ( n + 2 )}$ (4) $\frac{nd}{d + 2 n}$ 166. $A concave mirror for face viewing has focal length of 0.4 m The distance at which you hold the mirror from your face in order to see your image upright with a magnification of 5 is:$ (1) $0.24 m$ (2) $1.60 m$ (3) $0.32 m$ (4) $0.16 m$ 167. $A person is suffering from myopic defect. He is able to see clear objects placed at 15 cm. What type and of what focal length of lens he should use to see clearly the object placed 60 cm away$ (1) $Concave lens of 20 cm focal length$ (2) $Convex lens of 20 cm focal length$ (3) $Concave lens of 12 cm focal length$ (4) $Convex lens of 12 cm focal length$ 168. $Given below are two statements: one is labelled as Assertion (A)and the other is labelled as Reason (R).Assertion (A): Refractive index of glass is higher than that of air.Reason (R): Optical density of a medium is directly proportionate to its mass density which results in a proportionate refractive index.In the light of the above statements, choose the most appropriate answer from the options given below:$ (1) $Both (A)and (R) are correct and (R) is the correct explanation of (A)$ (2) $(A) is correct but (R) is not correct$ (3) $(A) is not correct but (R) is correct$ (4) $Both (A)and (R) are correct but (R) is not the correct explanation of (A)$ 169. $Focal length of a conver lens will be maximum for$ (1) $Green light$ (2) $Blue light$ (3) $Red light$ (4) $Yellow light$ 170. $If the scattering intensity of a liquid is 8 units at a wavelength of 500 nm, then the scattering intensity at a wavelength of 400 nm will be approximately$ (1) $13 units$ (2) $16 units$ (3) $20 units$ (4) $24 units$ 171. $An electromagnetic radiation of frequency , wavelength , travelling with velocity in air, enters a glass slab of refractive index . The frequency, wavelength and velocity oflight in the glass slab will be respectively$ (1) $n, 2 λ and \frac{v}{μ}$ (2) $\frac{2 n}{μ}, \frac{λ}{μ} and v$ (3) $\frac{n}{μ}, \frac{λ}{μ} and \frac{v}{μ}$ (4) $n, \frac{λ}{μ} and \frac{v}{μ}$ 172. $For a given pair of transparent media, the critical angle for which colour is maximum?$ (1) $Green$ (2) $Red$ (3) $Blue$ (4) $Violet$ 173. $A prism of certain angle deviates the red and blue rays by 8^{\circ} and 12^{\circ} respectively. Another prism of the same angle deviates the red and blue rays by 10^{\circ} and 14^{\circ} respectively. The prisms are small angled and made of different materials. The dispersive powers of the materials of the prisms are in the ratio$ (1) $5 : 6$ (2) $9 : 11$ (3) $6 : 5$ (4) $11 : 9$ 174. $The equiconvex lens has a focal length ' f'. If the lens is cut along the line perpendicular to principal axis and passing through the pole, what will be the focal length of any half part?$ (1) $\frac{f}{2}$ (2) $2 f$ (3) $\frac{3 f}{2}$ (4) $f$ 175. $Frequencies of light incident on a system of scattering particles are in the ratio of 1 : 2 . Then, the intensity of scattered light in a particular direction is ...$ (1) $1 : 4$ (2) $1 : 2$ (3) $1 : 8$ (4) $1 : 16$ 176. $The refracting angle of a prism is and refractive index of material of prism is . The angle of minimum deviation is$ (1) $90^{\circ} - A$ (2) $180^{\circ} - 2 A$ (3) $180^{\circ} - 3 A$ (4) $180^{\circ} + 2 A$ 177. $A thin convex lens of focal length made of crown glass is immersed in a liquid of refractive index , where is the refractive index of the crown glass. The convex lens now is$ (1) $a convex lens of longer focal length$ (2) $a convex lens of shorter focal length$ (3) $. a divergent lens$ (4) $a convex lens of focal length (μ_{c} - μ_{l}) f$ 178. $The blue colour of the sky is due to the phenomenon of$ (1) $scattering$ (2) $dispersion$ (3) $reflection$ (4) $refraction.$ 179. $Two particles move at right angle to each other. Their de Broglie wavelengths are λ_{1} and λ_{2} respectively. The particles suffer perfectly inelastic collision. The de Broglie wavelength λ of the final particle, is given by:$ (1) $\frac{1}{λ ^{2}} = \frac{1}{λ _{1}^{2}} + \frac{1}{λ _{2}^{2}}$ (2) $λ = λ_{1} λ_{2}$ (3) $λ = \frac{λ _{2} + λ _{2}}{2}$ (4) $\frac{2}{λ} = \frac{1}{λ _{1}} + \frac{1}{λ _{2}}$ 180. $A person wants a real image of his own, 3 times enlarged. Where should he stand infront of a concave mirror of radius of curvature 30 cm ?$ (1) $30 cm$ (2) $20 cm$ (3) $10 cm$ (4) $90 cm$