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A concave mirror has a focal length of 20 cm. Find the position or positions of an object for which the image-size is double of the object-size. |
Answer» Correct Answer - A::C For the concave mirror, `f=-20cm` `M=v/u=2` `rarr v=-2u` Ist case (virtual image) `1/v+1/u=1/f` `rarr 1/(2u)1/u=1/f` `rarr 1/(2u)=1/f` `rarr u=f/2=10cm` `:.` The positions are 10 cm or 30 cm from the concave mirror. |
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