Question

A light ray strikes a plane mirror making an angle of ${25}^{\circ }$ with the mirror. The angle between the incident and reflected ray is

• A. ${130}^{\circ }$
• B. ${110}^{\circ }$
• C. ${50}^{\circ }$
• D. ${25}^{\circ }$

Answer 1

The correct option is A ${130}^{\circ }$


Angle made by incident ray with plane mirror $\angle ABM={25}^{\circ }$
$OB$ is the normal to the plane mirror
Angle of incidence $\angle ABO={90}^{\circ }-{25}^{\circ }={65}^{\circ }$
Using law of reflection
Angle of incidence $\angle ABO=$ Angle ofreflection $\angle CBO$
So angle of reflection $\angle CBO={65}^{\circ }$
Angle between incident and reflected ray $\angle ABC={65}^{\circ }+{65}^{\circ }={130}^{\circ }$