AP Polycet (Polytechnic) 2022 Previous Question Paper with Answers And Model Papers With Complete Analysis

61) If A and B are the speed of light in a medium and refractive index of that medium respectively, then

A) A is low when B is high
B) A is high when B is high
C) A is independent of B
D) None of these

View Answer

A) A is low when B is high

Explanation:If A is speed of light in a medium and B is refractive index:
$\text{Refractive index } (n = \frac{c}{v}) ⇒ \text{Higher } n ⇒ \text{Lower } v$
Answer:A is low when B is high

62) The refractive index of glass with respect to air is 2. The critical angle at their interface is

A) 90°
B) 60°
C) 45°
D) 30°

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D) 30°

Explanation:Critical angle formula:
$\sin C = \frac{1}{n}, \quad n = 2 ⇒ C = \sin^{-1}\left(\frac{1}{2}\right) = 30^\circ$

63) The symbol ↕ used to draw the ray diagrams indicates

A) concave lens
B) convex lens
C) plano-concave lens
D) plane mirror

View Answer

D) plane mirror

Explanation:The symbol ↕ is conventionally used to represent a plane mirror in ray diagrams.Answer:Plane mirror

64) If y and $\frac y4$ are the object and image distances due to a convex lens respectively, then its focal length is

A) $\frac{5y}4$
B) $\frac{4y}5$
C) $\frac y5$
D) $\frac{3y}4$

View Answer

C) $\frac y5$

Explanation:Given:
Object distance $u = -y$ (for convex lens, object on left is negative)Image distance $v = \frac{y}{4}$
Use lens formula:
$\frac{1}{f} = \frac{1}{v} - \frac{1}{u} = \frac{1}{\frac{y}{4}} - \frac{1}{-y} = \frac{4}{y} + \frac{1}{y} = \frac{5}{y} ⇒ f = \frac{y}{5}$

65) A lens bounded by two spherical surfaces curved inwards is

A) double concave
B) double convex
C) plano-concave
D) plano – convex

View Answer

A) double concave

Explanation:Lens curved inward on both sides → double concave lensAnswer:Double concave

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