Question

describe the method used to measure the focal length of a concave mirror....​

Answer 1

$\huge \mathtt{Answer} \over$

To determine the focal length of a concave mirror, by obtaining image of a distant object. A concave mirror, a rectangular piece of wood as a screen or white wall and a meter scale. A distant object situated at a distance which is many many times the focal length of a mirror is regarded as an object at infinity.

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Answer 2

$\huge \ \tt \frac{1}{f} = \frac{1}{v} + \frac{1}{u} \: \: \:$

• adding reciprocal of image distance and object distance which is equal to reciprocal of focal length of mirror

Simplifed (easy way) formula

it is LCM way simplified formula

$\huge \tt \frac{1}{f} = \frac{u + v}{u(v)}$