Question

A beam of light consisting of red, green, and blue colors is incident on a right-angled prism. The refractive indices of the material of the prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47, repectively. The prism will

A. Separate part of the blue colour from the red and green
B. Separate part of the red colour from the greem and blue colours
C. Separate all the three colours from one another
D. None of these

Answer 1

Correct Answer - B
The critical angles `[C=sin^(-1)(1)/(n)]` for need (n=1.39), green (n=1.44) and blue (n=1.47) lights are `46^(@) , 44^(@) and 43^(@)` respectively. All colous will strike the hypotenuse face at `45^(@)`. Hence green and blue rays will totally reflected while red rays will get through.