Geometrical optics LENSES Refraction

[kthouz]

Homework Statement

A lens is made of glass for which the refractive index is n[r]=1.5 for red beams and n[v]=1.52 for violet beams. radii of both surfaces are the same and equal R=1m. Find the distance between foci for red and violet beams

Homework Equations

The Attempt at a Solution

 

[Kurdt]

What have you tried?

 

[kthouz]

I tried to sketch the situation. there i can get all possible relations between angles on both of the beams. The incident angle will be the same for both two beams. But now, how can i introduce the radius in my relations. Is there any formula conecting a lense's radius with the angle of incidence?

 

[Kurdt]

There is and it is called the lens makers formula.

http://hyperphysics.phy-astr.gsu.edu/Hbase/geoopt/lenmak.html

 

[kthouz]

thank you Kurdt.