Question

 A ray of light is incident normally on a glass slab of thickness 5 cm and refractive index 1.6. The time taken to travel by a ray from source to surface of slab is same as to travel through glass slab. The distance of source from the surface is

Answer 1

So for angles of incidence greater than 48.6-degrees, TIR occurs. But 48.6 degrees is the critical angle only for the water-air boundary. The actual value of the critical angle is dependent upon the two materials on either side of the boundary. For the crown glass-air boundary, the critical angle is 41.1 degrees.

Answer 2

Hey dear,


● Answer -
s = 8 cm

● Explanation -
# Given -
d = 5 cm = 0.05 m
μ = 1.6

# Solution -
Speed of light through given medium -
v = c / μ
v = 3×10^8 / 1.6
v = 1.875×10^8 m/s

Time taken by light to pass through glass slab is -
t = d / v
t = 0.05 / 1.875×10^8
t = 2.67×10^-10 s

Distance of source from surface is -
s = ct
s = 3×10^8 × 2.67×10^-10
s = 0.08 m
s = 8 cm

Therefore, distance of source from surface is 8 cm.

Hope this helps you...