Question

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

Answer 1

Correct Answer - C

Shift of O by slab`=3(1-(1)/(3//2))=1cm` above O
(Here O is outside slab)