The frequency of a light wave in a material is `2xx10^(14)Hz` and wavelength is `5000 Å`. The refractive index of material will be

Options

A. `1.40`
B. `1.50`
C. `3.00`
D. `1.33`

Answer

C

Explanation

Velocity of light waves in material is
`v= n lambda " "….(i)`
`mu = ( c)/( v) " "...(ii)`
Where c is speed of light in vacuum or air.
or `mu = ( c)/( n lambda) " "....(iii)`
Given, `n =2 xx 10^(14)` Hz
`lambda = 5000 Å = 5000 xx 10^(-10)`m
`c = 3 xxx 10^(5) "m/s"`
Hence, from Eq. (iii), we get
`mu = (3 xx 10^8)/( 2 xx 10^(14) xx 5000 xx 10^(-10) ) = 3. 00`