Time taken by sunlight to pass through a window of thickness 8 mm and refractive index (3/2) is:

$4×10^{-11}s$

The correct answer is Option (2) → $4×10^{-11}s$

The time taken by sunlight to pass through the window is -

$t=\frac{d}{v}$

$d = 8mm$ = Thickness of window

$v$ = speed of light

Also, speed of light in medium, $v=\frac{c}{μ}=\frac{3×10^8}{(3/2)}=2×10^8m/s$

$t=\frac{d}{v}=\frac{8×10^{-3}}{2×10^8}=4×10^{-11}s$