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NEET UG PHYSICS MCQ: RAY OPTICS

1 Medium

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Understanding +4 | -1

The optical fibres have an inner core of refractive index

{n_1}

and a cladding of refractive index

{n_2}

such that

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Correct option: D

{n_1} > {n_2}

Option D (

{n_1} > {n_2}

) is correct because total internal reflection requires the core to have a higher refractive index than the cladding.

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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