NEET UG PHYSICS MCQ: RAY OPTICS

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Analyzing +4 | -1

Two converging lens have focal length

f=10 \mathrm{~cm}

and

f^{\prime}=20 \mathrm{~cm}

respectively. The optical axes of the lenses coincide. This lens system is used to form an image of an object kept at a certain distance from the first lens. If the size of the final image does not depend on the distance of the object from the first lens. What is the distance (in

\mathrm{cm}

) between the two lens?

View answer and explanation

Correct option: A

Option A (30) is correct because for the final image size to be independent of the object distance, the lens system must act as a telescope, requiring the distance between the lenses to be the sum of their focal lengths.

More Questions from RAY OPTICS

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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