An object P is focused by a microscope M. A glass slab of thickness 2.1 cm is introduced between P and M. If the refractive index of the slab is 1.5, by what distance should the microscope be shifted to focus the object again?
The thickness of the glass slab, d = 2 cm
and refractive index of the slab μ = 1.5
shift due to the glass slab is given by
Δ T = (1−1/μ) d = (1−1/1.5)2.1 = 0.7 cm
So, the microscope should be shifted 0.70cm to focus the object again.