Question

A beam of light consisting of red, green and blue color is incident on a right angled prism. The RI's of the material of the prism for above red, green and blue wavelengths are 1.39, 1.44 and 1.47 respectively. The prism will

• A. Separate the red colour from the green and blue colours
• B. Seperate the blue colour from the red and green colours
• C. Seperate all the 3 colours from one another
• D. Not separate even partially any colour from the other two colours

Answer 1

The correct option is A

Separate the red colour from the green and blue colours

Here from given data we can easily conclude that critical angle for red is more than 45⁰ while for green and blue it is less than 45⁰. As light is incident on prism air interface at 45⁰so red will emerge from prism while green and blue will undergo TIR.