Question

A real image of an object is formed by a convex lens at the bottom of an empty beaker. The beaker is now filled with a liquid of refractive index 1.4 to a depth of 7 cm. In order to get the image again at the bottom, the beaker should be moved

• A. downward by 2 cm
• B. upward by 2 cm
• C. downward by 3 cm
• D. upward by 3 cm

Answer 1

The correct option is A downward by 2 cm

Due filling the water in the beaker, the rays bend on the surface of the liquid following Snell's law such that the image is shifted to the bottom.

$\frac{1}{v}=\frac{\mu }{d}$

$v=\frac{d}{\mu }$

Shift=$d-\frac{d}{\mu }=7-\frac{7}{1.4}=2cm$