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

66) A convex lens gives a virtual image when the object is placed on the principal axis

A) at infinity
B) at the centre of curvature
C) beyond the centre of curvature
D) between focal point and optic centre

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D) between focal point and optic centre

Explanation:Convex lens gives virtual image when object is placed between focus and optical center.Answer:Between focal point and optic centre

67) Which among the following pairs represents optically transparent and opaque media?

A) Water, glass
B) Water, ice
C) Ice, clay
D) clay, wood

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A) Water, glass

Explanation:Transparent = light passes through (e.g., ice), Opaque = light does not pass (e.g., clay)Answer:Ice, clay

68) If R₁ and R₂ are the radii of curvature, n is the refractive index and f is the focal length, then the lens maker’s formula is given by

A) $f=\left(n-1\right)\left(\frac1{R_1}-\frac1{R_2}\right)$
B) $f=\left(n-2\right)\left(\frac1{R_1}-\frac1{R_2}\right)$
C) $\frac1f=\left(n-2\right)\left(\frac1{R_1}-\frac1{R_2}\right)$
D) $\frac1f=\left(n-1\right)\left(\frac1{R_1}-\frac1{R_2}\right)$

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D) $\frac1f=\left(n-1\right)\left(\frac1{R_1}-\frac1{R_2}\right)$

Explanation:Lens maker’s formula:
$\frac{1}{f} = (n - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)$
Answer: $\frac{1}{f} = (n-1)\left( \frac{1}{R_1} - \frac{1}{R_2} \right)$

69) In case of myopic detect, the image is formed

A) before the retina
B) after the retina
C) on the retina
D) does not from an image

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A) before the retina

Explanation:In myopia (short-sightedness), image forms before the retina.Answer:Before the retina

70) The part of the human eye which helps the eye lens to change its focal length, is

A) iris
B) ciliary muscle
C) cornea
D) aqueous humour

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B) ciliary muscle

Explanation:Ciliary muscles control the shape of the lens and hence adjust focal length.
Answer:Ciliary muscle

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