Question

Answer these questions.....​

Answer 1

4) The principal focus of a convex lens is defined as the point on which the principal axis of the light is parallel to the principal axis that converges after the refraction from the lens. The principal focus of concave lens is when the light rays get diverged and appear to form a single point.

5)The astronomical telescope makes use of two positive lenses: the objective, which forms the image of a distant object at its focal length, and the eyepiece, which acts as a simple magnifier with which to view the image formed by the objective.