Arun
Last Activity: 6 Years ago
In the case of a plane mirror, the distance between the object and the mirror (d1) is same as the distance between the image and the mirror (d2).

Given,
Distance between the image and David = d1 + d2 = 4 m
Therefore, d1 = d2 = 2 m
If David moves 2 m away from the mirror, then d1 = 2 + 2 = 4 m
Again, d1 = d2 = 4 m
Therefore, the distance between David and his image is d1 + d2 = 4 + 4 = 8 m.
Regards
Arun (askIITians forum expert)