# An object of height 1.2 m is placed before a concave mirror of focal length 20 cm so that a real image is formed at a distance of 60 cm from it. Find

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An object of height 1.2 m is placed before a concave mirror of focal length 20 cm so that a real image is formed at a distance of 60 cm from it. Find the position of the object ? What will be the height of image formed ?

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Here, h_(1) = 1.2 m, f = -20 cm
v = -60 cm, u = ? h_(2) =?
From mirror formula
1/v + 1/u = 1/f
1/u = 1/f - 1/v = 1/(-20) + 1/60 = -1/30
u = -30 cm
Therefore the object is to be held at 30 cm in front of the mirror.
As h_(2)/h_(1) = (-v)/u = 60/(-30) = 2
:. h_(2) = -2h_(1) = -2 xx 1.2 m = -2.4 m
Negative sign represents inverted image.

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