Question

A microscope is sharply focused on a mark. When a parallel plate of glass 4.8 mm thick is placed over the mark, the microscope has to be raised 0.18 cm to refocus. What is the refractive index of the glass?

Answer 1

$thickness, t=4.8mm=0.48cm apparent\space depth=0.48-0.18=0.3$

real depth$=4.8cm$

refractive index $=real\space depth/apparent\space depth=0.48/0.3=1.6$