Question

If velocity of light in air is $C\,m/sec$ then what will be the velocity of light in medium of refractive index $1.4$?

• A. $2.1 \times 10^{8} m / s$
• B. $1.4 \times 10^{8} m / s$
• C. $2.8 \times 10^{8} m / s$
• D. None of these

Answer 1

Answer: (A)

Absolute refractive index
$=\frac{Speed of light in vaccum}{Speed in medium}$
$\mu=\frac{c}{v}$
So, speed in medium,
$v=\frac{3\times10^{8}}{1.4}=2.14\times10^{8} m / s$