Question

What is a thin lens?​

Answer 1

Explanation:

a thin lens is a lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the radii of curvature of the lens surfaces. ... The thin lens approximation ignores optical effects due to the thickness of lenses and simplifies ray tracing calculations

Answer 2

in a thin lens is a lens with a thickness (distance along the optical axis between the two surface of the lens)