An object is viewed through a compound microscope and appears in focus when it is ${\rm{5 mm}}$ away from the objective lens. When a sheet of transparent material ${\rm{3 mm}}$ thick is placed between the objective and the microscope, the objective lens has to be moved ${\rm{1 mm}}$ to bring the object back into the focus. The refractive index of the transparent material is

NEET UG PHYSICS MCQ: RAY OPTICS

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An object is viewed through a compound microscope and appears in focus when it is

\mathrm{5 mm}

away from the objective lens. When a sheet of transparent material

\mathrm{3 mm}

thick is placed between the objective and the microscope, the objective lens has to be moved

\mathrm{1 mm}

to bring the object back into the focus. The refractive index of the transparent material is

View answer and explanation

Correct option: A

1.5

Option A (1.5) is correct because it's calculated using the formula for apparent depth and the shift in the object's position due to the introduction of the transparent material.

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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