What is Principal Focus?

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.

The principal focus of Convex Mirror:

A number of rays which falls parallel to the principal axis after getting reflected, the rays seems to come from a point on the principal axis. This is called as Principal focus Convex Mirror.

The principal focus of Concave Mirror:

A number of rays which falls parallel to the principal axis on a concave mirror meets at a point on the principal axis after getting reflected. This is known as the principal focus of a concave mirror.

Check the video below for further reference.

1 Comment

  1. Hello byju’s
    You are doing a good job by teaching all these to students but try to make a web application for byju’s.
    Thank you

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