Question bank/JEE Main/Physics

JEE MainPhysicsModerateRay Optics

A concave mirror of radius of curvature 40 cm is filled with
water (n=4/3) upto a height of 12 cm. A point object O is kept on the

principal axis of the mirror at height 13.5 cm from the water surface.

The final image formed after refraction at water surface, reflection at

mirror and again refraction at water surface in succession is situated

at.

Show answer and solution
Refraction -1: Apparent depth from water surface
d′=13.5×43=18cmd^{'} = 13.5 \times \frac{4}{3} = 18cm
Reflection from concave mirror.

1v+1(−30)=1−20\frac{1}{v} + \frac{1}{( - 30)} = \frac{1}{- 20}
v=−60cmv = - 60cm
Image is formed 48 cm above water surface

Refraction-2:
d′′=484/3=36cmd^{''} = \frac{48}{4/3} = 36cm above water surface

Source: Grass-G / P-17 Physics paper 26 Nov Second.docx

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