Question

The angle between the incident ray and the reflected ray is $60°$. What is the value of the angle of incidence?

Answer 1

Step 1: Given

Let ${\theta }_i$ be the angle of incidence and ${\theta }_r$ be the angle of reflection. Then by the law of reflection,

Given, ${\theta }_i+{\theta }_r=60°$

Step 2: Formula used

The law of reflection states that when light falls on a smooth surface, the angle of incidence is equal to the angle of reflection.

${\theta }_i={\theta }_r$.

Step 3: Calculate angle of incidence

Simplifying the given expression,

$\begin{array}{cc}& {\theta }_i+{\theta }_r={60}^{°}\\ \Rightarrow & {\theta }_i+{\theta }_i=60°\left[\because {\theta }_i={\theta }_r\right]\\ \Rightarrow & {\theta }_i=30°\end{array}$

Therefore, the angle of incidence is $30°$.