Question

A boy stands 4 m away from the plane mirror. If the boy moves `1/2` m towards the mirror, what is now the distance between the boy and his image? Give a reason for your answer. 

Answer 1

Distance of boy from the plane mirror = u = 4 m When boy moves `1/2` m towards the mirror.
Then, distance between boy and mirror = 4 – `1/2` = `7/2` m
We know, in a plane mirror, the image formed is as behind the mirror as the object is in front of it.
So, distance between the mirror and image of boy = `7/2` m
Distance between the boy and his image
= Distance of boy from mirror + Distance of image of boy from mirror.

`= 7/2 + 7/2 = (7 + 7)/2 = 14/2` = 7 m