# Flat mirror

Discussion in 'MCAT Study Question Q&A' started by m25, Sep 29, 2014.

1. ### m25

304
19
May 28, 2014
So I know that if a person of height H wants to see his entire body in a flat mirror, the minimum height of the mirror needed is 0.5H.
So my question is, in order to see his his entire body in the flat mirror, does

1) his distance from mirror matter?
2) vertical location of the mirror matter?

and if so, where should they be?

3. ### amy_k

192
56
Sep 24, 2014
1) Distance from the mirror actually does not matter

2) The top of the mirror needs to be approximately the same height as you, specifically at least reaching to half the distance between your eyes and the top of your head

It is probably easiest to draw a diagram:

For 1)

If you move back further away from the mirror as shown, it will change the angles of incidence and reflection, but assuming a flat ground your height does not change as you move back, so the bottom of the mirror is still halfway between your eyes and feet, and therefore the length of mirror required to see your feet is the same.

For 2)

The top of the mirror needs to be a minimum height of halfway between your eyes and the top of your head so that the light from the top of your head could reflect back to your eyes as shown.

I hope this helps

m25 likes this.
4. ### m25

304
19
May 28, 2014
Ah, perfect. Thank you!!