Question

Find the focal length of a concave mirror of an object placed 20 cm in front of the mirror and gives a real image 60 cm from the same mirror. Please show me the solution.

Answer 1

Heya

Here,
u = -20 cm
v = -60 cm
f = ?

By mirror formula,

1/f = 1/v + 1/u
1/f = 1/-20 + 1/-60
1/f = -1/15

So,f = -15

Hence,the focal length of the concave mirror is -15 cm.

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