Question

A green light is incident from the water to the air - water interface at the critical angle $\left(\theta \right)$. Select the correct statement.

• A. The spectrum of visible light whose frequency is less than that of green light will come out of the air medium.
• B. The entire spectrum of visible light will come out of the water at various angles to the normal.
• C. The entire spectrum of visible light will come out of the wtaer at an angle of ${90}^{\circ }$ to the normal.
• D. The spectrum of visible light whose frequency is more than that of green light will come out to the air midium.

Answer 1

The correct option is A The spectrum of visible light whose frequency is less than that of green light will come out of the air medium.


Here, $\sin C=\frac{1}{n_{\text{water}}}$
and $n_{\text{water}}=a+\frac{b}{{\lambda }^2}$
If frequency is less $\Rightarrow \lambda$ is greater and hence $R.I\left(n_{\text{water}}\right)$ is less and therefore, critical angle increase.

Hence, Option $B$ is correct.