Chapter 17.1, Problem 7SSC

To determine

The angle that reflected ray make with the surface of the mirror.

Answer to Problem 7SSC

The angle of the reflected ray with the surface of the mirror is $10°$ .

Explanation of Solution

Given:

The angle of the light ray strikes the surface to the normal is ${\theta }_{\text{i}}=80°$

Formula used:

The expression for the law of reflection is,

  ${\theta }_{\text{r}}={\theta }_{\text{i}}$

Here, ${\theta }_{\text{i}}$ is the angle of the incident ray.

Calculation:

Sketch the situation as shown below.

  

The angle of the reflected ray is,

  $\begin{array}{l}{\theta }_{\text{r}}={\theta }_{\text{i}}\\ {\theta }_{\text{r}}=80°\end{array}$

The angle of the reflected ray with the surface of the mirror is

  $\begin{array}{l}\theta =90°-{\theta }_{\text{r}}\\ \theta =90°-80°\\ \theta =10°\end{array}$

Conclusion:

Thus, the angle of the reflected ray with the surface of the mirror is $10°$ .