Question

Define the following
Principal focus​

Answer 1

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.

Answer 2

principal focus, focus. the point on the axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection. 2. a central point of attention or interest.

Hopes helps you friend plz mark it's as brainliest answer.