Question

A light wave has a frequency of $4\times {10}^{14}\text{Hz}$ and a wavelength of $5\times {10}^{-7}\text{m}$ meters in a medium. The refractive index of the medium is :

• A. 1.5
• B. 1.33
• C. 1
• D. 0.66

Answer 1

The correct option is A 1.5

Given,

frequency, $f=4\times {10}^{14}$ Hz

Wavelength, $\lambda =5\times {10}^{-7}$m

velocity, $v=f\lambda$

$=4\times {10}^{14}\times 5\times {10}^{-7}$

$=20\times {10}^7$

$v=2\times {10}^{8}m/s$

Refractive index, $\mu =\frac{c}{v}$

$=\frac{3\times {10}^8}{2\times {10}^8}$

$\mu =1.5$.