Question

define the principal focus and focal length of a concave mirror

Answer 1

Answer:

A beam of light parallel to the principal axis after reflection from a concave mirror converges at a point on the principal axis. and that point is called Focus.

(See in the attachment, the Curve line is Concave mirror.) f is called the focal length. That is Length PF Is called Focal Length.

Explanation:

A Beam of light parallel to the principal axis after reflection form a concave mirror converges to a point on the principal axis. The Point is called Focus.

Focal Length → distance btw Focus to Pole.

EXTRA INFORMATION AS NOTE !!

• Focus (F) is a point where as focal length (f) is a distance.
• Concave mirror is clled Converging mirror because it converges a parallel beam light falling on it.
• Focal Length of concave mirror is always negative.

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Answer 2

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the principal axis of a concave mirror converge at a specific point on its principal axis after reflecting from the mirror.