Question

A plane mirror makes an angle of ${30}^{\circ }$ with horizontal. If a vertical ray strikes the mirror, find the angle between mirror and reflected ray.

• A. ${30}^{\circ }$
• B. ${45}^{\circ }$
• C. ${60}^{\circ }$
• D. ${90}^{\circ }$

Answer 1

Answer: (C)

Step 1: Given and diagram

The inclination of the mirror with horizontal=${30}^o$

The inclination of incident light and horizontal=${90}^o$

Draw a normal at the point of reflection.

Step 2: Formula used

The angle of incidence = angle of reflection

Step 3: Finding the angle between mirror and reflected ray

From the diagram,

The angle of incidence=${30}^o$

Normal angle= ${90}^o$

Hence, the angle of reflection=${30}^o$

The angle between the reflected ray and mirror= normal angle(${90}^o$ ) - angle of reflection(${30}^o$) =${60}^o$

Hence, the angle between reflected ray and mirror=${60}^o$.