Question

A ray of light passes from diamond to air. Critical angle is minimum for.

• A. Green
• B. Red
• C. Blue
• D. Yellow

Answer 1

The correct option is C Blue

$\mu \left(\lambda \right)=B+\frac{C}{{\lambda }^2}+\frac{D}{{\lambda }^4}+\dots \dots$ [cauchy's equation]

$\theta c={\sin }^{-1}\left(\frac{1}{\mu }\right)$

$\bullet$ For minimum critical angle, $\mu$ should be maximum.

$\bullet$ For $\mu$ to me maximum, $\lambda$ should be minimum.

hence, out of the following options, $Blue$ color will have minimum critical angle.