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NEET UG PHYSICS MCQ: RAY OPTICS

1 Medium

1 of 1

Analyzing +4 | -1

Assertion: A double convex lens

(\mu=1.5)

has focal length

10 \mathrm{~cm}

. When the lens is immersed in water

(\mu=4 / 3)

its focal length becomes

40 \mathrm{~cm}

.
Reason:

\frac{1}{f}=\frac{\mu_1-\mu_m}{\mu_m}\left(\frac{1}{R_1}-\frac{1}{R_2}\right)

View answer and explanation

Correct option: A

If both assertion and reason are true and the reason is the correct explanation of the assertion

Option A is correct because both the assertion and reason are true, and the reason correctly explains the assertion using the lens maker's formula.

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An object 5 cm tall is placed

\mathrm{1}\,\,\mathrm{m}

from a concave spherical mirror which has a radius of curvature of

\mathrm{20}\,\,\,\mathrm{cm}

. The size of the image is Red colour is used for danger signals because A ray of light is incident on the hypotenuse of a right-angled prism after travelling parallel to the base inside the prism. If

\mathrm{\mu }

is the refractive index of the material of the prism, the maximum value of the base angle for which light is totally reflected from the hypotenuse is Statement-A: The minimum distance between an object and its real image formed by a convex lens is

2{f}

.

Statement-B: The distance between an object and its real image is minimum when its magnification is -1. Assertion: We cannot produce a real image by plane or convex mirrors under any circumstances.
Reason: The focal length of a convex mirror is always taken negative. If both the object and image are at infinite distance from a refracting telescope its magnifying power will be equal to