Question

A man is 180 cm tall and his eyes are 10 cm below the top of his head. In order to see his entire height right from toe to head, he uses a plane mirror kept at a distance of 1 m from him. The minimum length of the plane mirror required is

• A. $180cm$
• B. $90cm$
• C. $85cm$
• D. $170cm$

Answer 1

The correct option is B $90cm$

$\begin{array}{c}\text{For a man to see his full body the minimum length of}\\ \text{mirror required is}\frac{h}{2}\text{[where is height of man)}\\ \text{It doesn't depend on any other factor except Height}\\ \Rightarrow \text{Length of mirror}=\frac{180}{2}=90cm\end{array}$