Question

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

Given,

$f=2\times {10}^{14}Hz$

$\lambda =5000\times {10}^{-10}m$

$c=3\times {10}^{8}m/s$

velocity,$v=f\lambda$

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

$v={10}^{8}m/s$

The refractive index of the material,

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

$\mu =3$

The correct option is B.