A parallel beam of white light is incident normally on a water film` 1.0 x 10^-4` cm thick. Find the wavelength in the visible range (400 nm-700 nm) which are strongly transmitted by the film Refractive index of water = 1.33.

Answer

A, B, C, D

Explanation

for strong transmission
`2mud=nm`
`rarr l=2(mud)/n`
Given that `mu=1.33,
`d=1xx10^-6 cm`
`=d=1xx10^-6m`
`- lamda=(2xx1.33xx1xx10^-6)/n`
`=(2660xx10^-9)/n m`
when `n=4, `lamda_1=665nm`
`n=5`
`lamda_2=532nm`
`n=6`
`lamda_3=443 nm`