# Optic question about a positive-meniscus lens

1. Oct 10, 2009

### mrquanta

i was asked to find the angle $$\theta$$, the height h2, and the back focal length in terms of the radius of curvatures. i'm really stunned that i couldn't draw a line. thanks in advance.

http://img94.imageshack.us/img94/8336/lens.png [Broken]

Last edited by a moderator: May 4, 2017
2. Oct 12, 2009

### gabbagabbahey

Hi mrquanta, welcome to PF!

You must show some attempt at a solution to receive help. We are not here to do your homework for you.

Why not start by calculating the angle of incidence (in terms of $h_1$ and $R_2$, via basic geometry) of the oncoming ray on the leftmost surface?...What does knowing that angle of incidence allow you to calculate (via Snell's Law)?