Question

A lens with an infinite focal length behaves like:

Options

• A concave mirror

• A strong diverging lens

• A simple plane sheet of glass

• A strong converging lens

Answer 1

When a lens has an infinite focal length, it does not converge or diverge light at all; it behaves like a simple plane sheet of glass. This occurs when the lens is immersed in a liquid of the same refractive index as the lens material.