Thread: Physics: Easy questions on light

1. Physics: Easy questions on light

Assume that your eyes are located at the top of your 1.60 m tall body.
a) What size plance mirror would you need to see your whole body if you were standing 1 m from it?
b) How far from the floor should the bottom edge of the mirror be placed?
c) How would your answers to (a) and (b) change if you assumed your eyes were 10 cm from the top of your head?
d) How would your answers to (a) and (b) change if you were 2 m from the mirror?

I'm not sure how to start these problems. However, I suspect that you'd have to know that the angle of incidence equals the angle of reflection since that seems the most relevant thing to what we've done so far. Anyway any explanations, tips or other help will be appreciated!

2. Originally Posted by Mr Rayon
Assume that your eyes are located at the top of your 1.60 m tall body.
a) What size plance mirror would you need to see your whole body if you were standing 1 m from it?
b) How far from the floor should the bottom edge of the mirror be placed?
c) How would your answers to (a) and (b) change if you assumed your eyes were 10 cm from the top of your head?
d) How would your answers to (a) and (b) change if you were 2 m from the mirror?

I'm not sure how to start these problems. However, I suspect that you'd have to know that the angle of incidence equals the angle of reflection since that seems the most relevant thing to what we've done so far. Anyway any explanations, tips or other help will be appreciated!
Draw a picture showing the limiting rays from your eyes to the image of your feet (and the top of your head). For you to be able to see your whole body in the mirror these limiting rays must pass through the mirror, and so define the minimum size of mirror to see your whole body.

CB