Chapter 9.3, Problem 23R

To determine

The angle of incidence.

Explanation of Solution

Introduction:

The law if reflection states that angle of incidence is always same to the angle of incidence.

The first law of reflection states that the angel of incidence is always same as the wangle of reflection. It can be written as,

$\text{Angle}\text{of}\text{incidence}=\text{Angle}\text{of}\text{reflection}$

Since the angle between a flashlight beam that strikes a mirror and the reflected beam is $80\text{degrees}$ . So, the angle of incidence is also $80\text{degrees}$ .

Conclusion:

The angle of incidence is $80\text{degrees}$ .