Question

Two plane mirrors are inclined at an angle $80$ degrees. A Ray of light is incident on one of the Mirrors. The ray after two reflection will undergo total deviation of:

• A. $180$ degrees
• B. $160$ degrees
• C. $200$ degrees
• D. $240$ degrees

Answer 1

The correct option is A $180$ degrees

Given that,

Angle $\theta ={80}^0$

We know that,

The reflection of light perpendicular to the first mirror it takes an angle of ${90}^0$ and since it is incident on the other plane mirror so, it will take an angle of ${90}^0$ as well.

Now, the total deviation

$={90}^0+{90}^0$

$={180}^0$

For every plane mirror of any angles

Hence, the total deviation is ${180}^0$