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The distance between the virtual image from its real object is 60 c m in case of a concave mirror and the image formed is 3 times magnified. What is the magnitude of focal length (in cm ) of the mirror?

Correct answer

22.5

Step-by-step solution

x   +   3 x = 60   ⇒ x = 15   c m u = - 15   c m m = +   3 ∴   m = f f - u ⇒   +   3 = f f - ( - 15 ) ∴   3 f +   45 = f   ⇒ f = -   22.5   c m f = 22 . 5   cm

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