# Reflection light mirror

1. Jun 19, 2009

### Mark1991

Hi!

The diagram below shows two mirrors X and Y, and a solid object with
white spots at P and Q.

http://img199.imageshack.us/img199/9284/unbenanntcwz.jpg [Broken]

An observer at A sees an image of P reflected in mirror Y. Mark R,
the position of this image, and draw a ray from P to the observer
at A.

Is my ray (yellow) and the location of the image right?

Mark

Last edited by a moderator: May 4, 2017
2. Jun 19, 2009

### mgb_phys

Not quite
The light bounces off the mirror at the same point it hits it and with the same angle from the normal.
ie. the two yellow lines must cross at the surface of the mirror.

3. Jun 19, 2009

### Staff: Mentor

Your image location looks perfect, but realize that the actual ray of light from P to A does not pass through the mirror.

Oops: mgb_phys beat me to it.

4. Jun 19, 2009

### Mark1991

Ok, another try:

http://img198.imageshack.us/img198/4567/unbenanntbfy.jpg [Broken]

I was of the opinion that you should draw a ray that goes straight to the image as it would if the mirror were only a glass plane.

So there are in fact two solutions:
The solution with a ray that hits the mirror in one point and bounced off in the same point
and the solution a ray seem to go straight to the image.

I think the observer in A would decide that my first solution is right, wouldn't he?

Mark

Last edited by a moderator: May 4, 2017
5. Jun 19, 2009

### mgb_phys

That's correct except the horizontal line from P to P' shouldn't be there

6. Jun 19, 2009

### Staff: Mentor

The reflected ray looks as if it comes straight from the image to the observer, as if you were looking through a window. (Of course, the actual reflected ray begins at the mirror surface.)

The incident ray goes from source to mirror, hitting the mirror at the point where the reflected ray begins.

No, there's only one solution.