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A tall man of height 6 feet wants to see his full image. Then required minimum length of the mirror will be :
A
12 feet
B
3 feet
C
6 feet
D
Any length
Detailed Solution
To see the full image in a vertical plane mirror, rays from the top of the head and from the feet must reflect into the eyes.
By the laws of reflection, these rays strike the mirror at points halfway (in height) between the eye and the head, and between the eye and the feet.
So the minimum length of the mirror is half the height of the person: $\dfrac{h}{2} = \dfrac{6}{2} = 3$ feet.
This does not depend on the distance from the mirror.
By the laws of reflection, these rays strike the mirror at points halfway (in height) between the eye and the head, and between the eye and the feet.
So the minimum length of the mirror is half the height of the person: $\dfrac{h}{2} = \dfrac{6}{2} = 3$ feet.
This does not depend on the distance from the mirror.