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Question: The focal length of a concave mirror is ![](https://cdn.pureessence.tech/canvas_164.png?top_left_x=1...

The focal length of a concave mirror is Where an object be placed so that its image is two times and inverted

A

75 cm

B

72 cm

C

63 cm

D

50 cm

Answer

75 cm

Explanation

Solution

For real image m = – 2, so by using m=ff−um = \frac { f } { f - u }

⇒−2=−50−50−u⇒u=−75 cm\Rightarrow - 2 = \frac { - 50 } { - 50 - u } \Rightarrow u = - 75 \mathrm {~cm}