A concave mirror gives an image three times as large as the object placed at a distance of $20\ cm$ from it. For the image to be real, the focal length should be

Question

Dr. Abubacker · Accepted Answer

(b) $m = \frac{f}{f - u} \Rightarrow - 3 = \frac{f}{f - ( - 20)} \Rightarrow f = - 15\ cm$

Q. A concave mirror gives an image three times as large as the object placed at a distance of $20\ cm$ from it. For the image to be real, the focal length should be

Explanation

Reviewed by Dr. Abubacker

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