Question

Light of wavelength 6000Å is incident on a thin glass plate of refractive index 1.5 such that angle of refraction into the plate is `60^(@)`. Calculate the smallest thickness of plate which will make it appear dark by reflection.

Answer 1

`2mutcosr=nlamdaimpliest=(nlamda)/(2mucosr)=(1xx6xx10^(-7))/(2xx1.5xxcos60)=(6xx10^(-7))/(1.5)=4xx10^(-7)m`