Question

Light travels through a glass plate of thickness t and having refractive index n. If c is the velocity of light in vacuum, the time taken by the light to travel this thickness of glass is
(a) $\frac{t}{nc}$
(b) tnc
(c) $\frac{nt}{c}$
(d) $\frac{tc}{n}$

Answer 1

Speed =distance /time

Distance =refractive index×thickness

C=n×t/time

So ,t=n×t/c

Answer 2

Answer:

c) nt/c

Explanation:

Total thickness of the glass plate = t (Given)

Refractive index = n  (Given)

Velocity of the light in vacuum = c (Given)

Therefore, the speed of light in Glass plate = c/u

V = Speed of light in vacuum/ RI of the medium

Thus,

1/n=v/c

V = c/n

Time taken by light to travel the thickness of the glass plate

= distance/velocity

= t/c/n

= nt/c

Hence, the time taken by the light to travel this thickness of glass is nt/c.