Question

It is necessary to illuminate the bottom of a well by reflected solar beam when the light is incident at an angle ${40}^o$ to the vertical. At what angle to the horizontal should a plane mirror be placed?

• A. ${65}^o$
• B. ${70}^o$
• C. ${75}^o$
• D. ${80}^o$

Answer 1

The correct option is B ${70}^o$

$\begin{array}{c}i+r=i+i=140\\ ori={70}^0\end{array}$

Thus, plane mirror makes an angle of ${20}^0$ with vertical and ${70}^0$ with horizontal.

Therefore , the correct answer is option $C$.