Question

If the speed of light in medium -1 and medium -2 are 2.5 x ${10}^{8}m{s}^{-1}$ and 2 x ${10}^8$, $m{s}^{-1}$ respectively then what is the refractive index of medium -1 with respect to medium -2?

• A. $\frac{4}{5}$
• B. $\frac{3}{2}$
• C. $\frac{4}{3}$
• D. $\frac{5}{3}$

Answer 1

The correct option is A $\frac{4}{5}$

It is to be noted that
$\mu =\frac{speedoflightinvaccum}{speedoflightinmedium}$
Hence, ${\mu }_1=\frac{3/{10}^8}{2.5/{10}^8}$ and ${\mu }_2=\frac{3/{10}^8}{2/{10}^8}$
Now , Refractive index of medium (1) w.r.t. medium (2)
${\mu }_2=\frac{{\mu }_1}{{\mu }_2}=\frac{3/{10}^8}{2.5/{10}^8}/\frac{2/{10}^8}{3/{10}^8}$
${\mu }_2=\frac{4}{5}$