Find the distance from the mirrors for 4 reflections

[annalian]

Homework Statement

Two plain mirrors are put parallelly and 20 cm from each other. A source of light is put between the mirrors, 5 cm away from one. Find the distance from the mirrors of 4 first reflections.

Homework Equations

a1=a2 The distance of the object from the mirror and the reflection from the mirror is equal.

The Attempt at a Solution

http://s32.postimg.org/507dau85h/image.png
is it right?

 

[CWatters]

I know what a "first reflection" is but I'm not sure how you can have four of them in this situation. I think two are first reflections and two are second reflections. Check the distance for the one I marked incorrect.

 

[annalian]

I know what a "first reflection" is but I'm not sure how you can have four of them in this situation. I think two are first reflections and two are second reflections. Check the distance for the one I marked incorrect.

View attachment 100962

5 should be replaced with 10. Am I right?

 

[CWatters]

Yes.