What will be the time by light to travel 2 cm thickness of glass of refractive index 1.5?

$10^{10} s$

The correct answer is Option (4) → $10^{10} s$

Time taken (t) by light to travel through 2 cm (d) of a glass with refractive index (u) = 1.5 is -

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

where,

v = velocity of light in glass = $\frac{c}{u}$

$∴t=\frac{d×u}{c}=\frac{0.02×1.5}{2^3×10^8}$

$=10^{10} s$