Question

how much time will light take to cross 2 mm thick glass pane if refractive index of glass is 3/2?

Answer 1

Distance to be covered by the light through the glass = 2mm = 0.002 m

Refractive index of the glass = 1.5

Speed of light in air = $3 \times 10^8$ m/s

Speed of light in glass = $\frac{3 \times 10^8}{1.5}$ m/s

Speef of light in glass = $2 \times 10^8$ m/s

Time taken = $\frac{Distance}{Speed}$

Time taken = $\frac{0.002}{2 \times 10^8}$

$Time = 10^-^1^1$ seconds

Hence, the time taken by the light: $Time = 10^-^1^1$ seconds

Answer 2

The time taken is 10^-11 seconds.