. Define the term principal foci of a convex lens and illustrate your answer with the aid of proper diagrams

Best Answer

A light ray can pass through a lens from either side. Hence, a lens has two principal foci, one on either side of the lens.

For a convex lens, the first focal point is a point F₁ on the principal axis of the lens such that the rays of light coming from it, after refraction through lens, become parallel to the principal axis of the lens.

For a convex lens, the second focal point is a point F₂ on the principal axis of the lens such that the rays of light incident parallel to the principal axis, after refraction from the lens, pass through it.