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प्रश्न
Define the terms focus and focal length of a concave mirror. Draw diagram to illustrate your answer.
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उत्तर
Focus of a concave mirror: The focus of a concave mirror is a point on the principal axis through which the light rays incident parallel to principal axis, pass after reflection from the mirror.
Focal length of a concave mirror: The distance of the focus from the pole of the concave mirror is called its focal length.

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