Diverged lens?

Question

Which would have a greater focal length and why? a thin or thick diverged lens?

thankyou

also, can an image in a diverging lens be placed onto a screen? why or why not?

Answer 1

Assuming that a thicker lens is one with more curvature, and comparing it to a thinner lens of the same diameter and refractive index, the thinner lens would have a greater focal length since its front and rear surfaces are closer to parallel so it doesn't bend the light passing through it as much.
Since a diverging lens spreads parallel rays passing through it, it cannot project an image. Parallel rays from a point at infinity cannot converge to a point in a real image, but do converge to a point in the virtual image which is located in front of the lens (see ref.).