# Refraction and displacement

1. Jan 29, 2006

### Pixter

Okej have a piece of glass with refractive index n2 and tickness t.

A ray of light falls on the glass with the angle theta1 (from a medium with recrative index n1).

In the glass the ray has the angle theta2 and when it exits it has now got the displacement d (compared with the ray that went from air to glass).

Now show that the formula d=tsin(theta1)(1-(n1cos(theta1) / n2cos(theta2)) is correct.

I know it is suppose to be simple trig, but the only thing i can even figure out to do is that 90-theta1 = theta ... then i'm stuck.. can't see how to connect anything. please give me some hints.

Last edited: Jan 29, 2006
2. Jan 29, 2006

### Hootenanny

Staff Emeritus
Have you drawn a diagram? Hint: the incident ray and the the final refracted ray should be parallel.

3. Jan 29, 2006

### Pixter

yeah they are parallel of course.. but just finding the displacement of them..

have done a diagram as well. but as I said I can't figure out what to start with. can't see the trig stuff in it =(

4. Jan 29, 2006

### Pixter

Oki done it know.. and it made perfect sense..=)

Last edited: Jan 29, 2006
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