Calculate the radius of spherical convex mirror given that an object is placed at 60 cm from a mirror and the mirror is formed a virtual image 20 cm from the mirror.

7.5 m

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15 cm

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30 cm

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60 cm

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120 cm

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Solution

The correct option is D 60 cm
The focal length formula for convex mirror is given by $1 / f = 1 / u + 1 / v$
According sign convention of mirror , $u = - 60 c m$ and $v = 20 c m$
so, $1 / f = 1 / (- 60) + 1 / 20 = 1 / 30$ or $f = 30 c m$
If R be the radius of curvature , then $f = R / 2$ or $R = 2 f = 2 (30) = 60 c m$

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Calculate the radius of spherical convex mirror given that an object is placed at 60 cm from a mirror and the mirror is formed a virtual image 20 cm from the mirror.

The correct option is D 60 cmThe focal length formula for convex mirror is given by 1/f=1/u+1/vAccording sign convention of mirror , u=−60cm and v=20cmso, 1/f=1/(−60)+1/20=1/30 or f=30cmIf R be the radius of curvature , then f=R/2 or R=2f=2(30)=60cm