question_answer

A man is \[180cm\] tall and his eyes are \[10cm\] 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 \[1m\] from him. The minimum length of the plane mirror required is [MP PMT 1993; DPMT 2001]

A)            \[180cm\]                              

B)            \[90cm\]

C)            \[85cm\]                                

D)            \[170cm\]

Correct Answer: B

Solution :

                   According to the following ray diagram length of mirror \[=\frac{1}{2}(10+170)=90\,cm\]