A microscope is focused on a mark on a piece of paper and then a slab of glass of thickness `3cm` and refractive index `1.5` is placed over the mark. How should the microscope be moved to get the mark in focus again ?

Options

A. 1 cm downward
B. 2 cm upward
C. 1 cm upward
D. 4.5 cm downward

Answer

C

Explanation

`d_("app") = (d_("actual"))/(n) = (3)/(1.5) = 2 cm `
Since, image appears to be raised by 1cm, hence microscope must be moved upwards by 1cm.