- #1
bowlbase
- 146
- 2
Homework Statement
I have a compound thick lens problem that I need to find the sign of the refractive power.
Homework Equations
Thick lens equation and focal length equation.
The Attempt at a Solution
I believe all I need to do is calculate the focal length of the first two thick lenses and then use that result as the first "lens" in the same focal length equation again:
##\frac{1}{f_{12}}=\frac{1}{f_{1}}+\frac{1}{f_{2}}-\frac{d_{12}}{f_{1}f_{2}}##
##\frac{1}{f_{123}}=\frac{1}{f_{12}}+\frac{1}{f_{3}}-\frac{d_{123}}{f_{12}f_{3}}##
Is this a correct (or correct enough approximation) to get the sign?