Question

The frequency of a light wave in a material is $2\times {10}^{14}$ Hz and wavelength is 5000 $A^o$. The refractive index of material will be:

• A. 1.5
• B. 3
• C. 1.33
• D. 1.4

Answer 1

The correct option is B 3

$\mu =\frac{\text{velocity of light in vacuum (c)}}{\text{velocity of light in medium (v)}}$

But $v=\nu \lambda =2\times {10}^{14}\times 5000\times {10}^{-10}$

In the medium, $\mu =\frac{v_{vac}}{v_{med}}=\frac{3\times {10}^8}{{10}^8}=3$