Answer to Question #82850 in Optics for Khadeeja

Question

Two thin lenses of focal length f, and f, are in contact. The focal length f of the lens combination is given by

Answer 1

This combination of lenses behaves like a thin lens having a focal length F given by

1/F=1/f+1/f=2/f.

The focal length f of the lens combination is given by

F=f/2.