Question

A beam of light consisting of red, green and blue colours is incident on a right angled prism. The refractive index of the material of the prism for the red, green and blue colours are $1.39$, $1.44$ and $1.47$ respectively. The prism will

• A. separate the red colour from the green and blue colours
• B. separate the blue colour from the red and green colours
• C. separate all the three colours from one another
• D. not separate the three colours at all

Answer 1

The correct option is A separate the red colour from the green and blue colours

$\mu =\frac{1}{\sin i_c}=\frac{1}{\sin 45°}=\sqrt{2}=1.414{\mu }_{red}=1.39<\mu {\mu }_{blue}>\mu {\mu }_{green}>\mu$
Since $\mu$ of green and violet are greater than 1.414 so they will suffer total internal reflection. Only red colour does not suffer total internal reflection