Question

A light wave enters from air into a medium of refractive index $\mathrm{1.5.}$ The speed of light in the medium will be ____________.

• A. $1\times {10}^{8}m/s$.
• B. $2\times {10}^{8}m/s$.
• C. $3\times {10}^{8}m/s$.
• D. $4\times {10}^{8}m/s$.

Answer 1

The correct option is B $2\times {10}^{8}m/s$.

The refractive index is given as,

$\mu =\frac{c}{v}$

$1.5=\frac{3\times {10}^8}{v}$

$v=2\times {10}^{8}m/s$

Thus, the speed of light in the medium will be $2\times {10}^{8}m/s$.