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JEE Main & Advanced Sample Paper JEE Main Sample Paper-42

  • question_answer
    Find the distance between the object and its doubly magnified real image by a concave mirror of focal length f.

    A)  2f                               

    B) \[\frac{3f}{2}\]

    C) \[\frac{5f}{2}\]                                   

    D)  3f

    Correct Answer: B

    Solution :

    \[m=-(v/u)\]\[\Rightarrow \]\[-2=-v/u\]  [- ve magnification because image is real] \[\Rightarrow \]\[v=2u\] From mirror formula, \[(1/v)+(1/u)=(1/f)\] \[(1/2u)+(1/u)=(1/f)\] \[\Rightarrow \]\[3/2u=1/f\]\[\Rightarrow \]\[u=3f/2\]


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