Question

Time required for the light to pass through a glass slab of thickness 4 millimetre is

Answer 1

Refractive index of glass is 1.5

Refractive index (n) is given by

n = c / v
= c / (x/t) ……[∵ speed = distance/time]
= ct/x

t = nx/c
= (1.5 × 4 × 10^-3 m) / (3 × 10^8 m/s)
= 2 × 10^-11 s
= 0.02 nanosecond

∴ Time taken is 0.02 nanosecond

Answer 2

Answer:

Time required for the light to pass is $2\times 10^{-11}\ s$

Explanation:

It is given that,

Thickness of glass slab, x = 4 mm = 0.004 m

The refractive index of glass is 1.5

We have to find the time required for the light to pass through a glass slab.

Refractive index is given by :

$n=\dfrac{c}{v}$

c is speed of light

v is velocity of light in a medium, v = x/t

$n=\dfrac{ct}{x}$

$t=\dfrac{nx}{c}$

$t=\dfrac{1.5\times 0.004\ m}{3\times 10^8\ m/s}$

$t=2\times 10^{-11}\ s$

Hence, this is the required solution.