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An object is placed at 20 cm in front of...

An object is placed at 20 cm in front of a concave mirror produces three times magnified real image. What is focal length of the concave mirror ?

A

15 cm

B

6.6 cm

C

10 cm

D

7.5 cm

Text Solution

Verified by Experts

The correct Answer is:
A
`m= (f)/(f-u) rArr -3 = (f)/(f-(-20))`
`-3f + 60 = f`
`f = -15 cm`
Since mirror is concave f = 15 cm
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