# Homework Help: Apparent Depth of Light Bulb above Water and Mirror

1. Mar 17, 2015

### Santino Torres

1. The problem statement, all variables and given/known data
Hey, so there is a light bulb above a tank of water which has a mirror at the bottom. I am trying to find the apparent depth of the image of the light produced by the mirror. Finding the apparent depth of the mirror is easy, but I am confused on what to consider the object distance for the mirror to find the image distance. Should it be the apparent depth of the light bulb looking from the water (doesn't seem right)?

2. Relevant equations
The given equations were d=d'/n
& s=-s'

3. The attempt at a solution
So I would have s = (the actual distance from the mirror to the light bulb)(n of water)
so the apparent depth of the image would be {s+(the actual depth of the mirror)}/n below the surface of the water
Does this seem right or am I way off? Thanks for any help

2. Mar 18, 2015

### haruspex

I'm not entirely sure what you are proposing, but it doesn't seem right.
Pretend the mirror is just a sheet of clear glass, that there is a real light bulb where the image is, and correspondingly a depth of water below the glass and an airspace below that. I.e. The entire mirror image is real. Label upper light bulb L, upper water surface W, galss sheet G, then W' and L' for water surface and light bulb below. What would the distance of L' appear to be to an observer at W'? To an observer at G? And so forth.