Question

A wavefront $AB$ is incident on the surface as shown in the figure. What is the angle of incidence?

• A. ${90}^{\circ }-i$
• B. ${45}^{\circ }-i$
• C. $i$
• D. ${90}^{\circ }+i$

Answer 1

The correct option is C $i$



If $AB$ is the wavefront, a ray can be shown as $PO$.
$\Rightarrow AB\perp PO$

By the geometry of the figure,
$\angle POA=i$
$\therefore$ angle of incidence $=\angle PON=i$

Hence, $\left(C\right)$ is the correct answer.

$\begin{array}{c}\text{Why this question?}\\ \text{Note:- The direction of propagation of light on a point of wavefront is perpendicular to the wavefront at that point.}\end{array}$