Question

Define focus and focal length of a concave mirror

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Answer 1

point at which all the incident ray converges is called focus

and the distance from pole of the mirror to the focus point is called focal length

Answer 2

Explanation:

Principal Focus:- It is a point at which all the rays appear to meet or appear to diverge after reflecting from the curved surface of the spherical mirrors.

The concave mirror reflects the parallel rays of light in such a way that, after reflection, all the rays of light meet at one point called focus. All the parallel rays of light converge at this point. The focus of a concave mirror is in front of mirror. The focus of a concave mirror is real because light rays actually passes through it. Since, a concave mirror converges a beam of parallel rays, therefore, a concave mirror is also known as converging mirror.

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