Question

The speed of light in glass is $2\times {10}^5$ $km/s$. What is the refractive index of glass?

Answer 1

Refractive index of glass $=\frac{speedoflightinvacuum}{speedoflightinglass}$
$=\frac{3\times {10}^{8}m/s}{2\times {10}^{5}km/s}=\frac{3\times {10}^{8}m/s}{2\times {10}^{8}m/s}$
$=1.5$