Convex lens is put 10 cm from a light source and it makes a sharp image on a screen, kept 10 cm from the lens. Now a glass block (refractive index1.5) of 1.5 cm thickness is placed in contact with the light source. To get the sharp image again, the screen is shifted by a distance d. Then d is:-
Refraction through parallel slab -
- wherein
shifting of object from slab
thickness of slab
Refractive Index of slab.
F = = 5 cm
Due to glass plate shift
s = t
= 1.5
= 0.5
New u =9.5 cm
Using lens formula
=
v = 10.55 cm
Shift is 0.55 cm away from the lens.