Question

Define principal axis and principal focus?​

Answer 1

Answer:

Focus is the point where light rays originating from a point on the object converge. The principal focus is defined as the point where a beam parallel to the principal axis appears to diverge converges from a point on the principal axis after passing through the lens.

A line passing through the center of the surface of a lens or spherical mirror and through the centers of curvature of all segments of the lens or mirror.

Answer 2

Answer:

Principal axis :- The line joining the centres of curvature of the two surfaces of a lens is known as its principal axis.

principal Focus :- It turns out that if a beam of rays, all parallel to the principal axis of a lens, falls on the lens, all such rays either all coverage to a point on its principal axis, or appear to diverge from a point on its principal axis. We call this point as the (second) principal focus of the lens

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