Chapter 17, Problem 79A

To determine

The new angle of reflection.

Answer to Problem 79A

  $62°$

Explanation of Solution

Given:

Initial angle of incidence to the normal, $\theta =28°$

Increase in the angle of incidence, $\theta \text{'}=34°$

Formula used:

For the mirror,

  $\begin{array}{c}\text{angle of incidence = angle of reflection}\\ {\theta }_i={\theta }_r\end{array}$

Calculation:

Now, after the source of light is moved, the new angle of incidence is,

  $\begin{array}{c}{\theta }_i=\theta +\theta \text{'}\\ =28°+34°\\ =62°\end{array}$

Then, using the property of mirrors, new angle of reflection will be,

  ${\theta }_r={\theta }_i=62°$

Conclusion:

Therefore, the new angle of reflection is $62°$ .