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JEE Main & Advanced Physics Ray Optics Question Bank Spherical Mirror

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    Radius of curvature of concave mirror is \[40cm\] and the size of image is twice as that of object, then the object distance is [AFMC 1995]

    A)            \[60cm\]                                

    B)            \[20cm\]

    C)            \[40cm\]                                

    D)            \[30cm\]

    Correct Answer: D

    Solution :

                       \[f=\frac{R}{2}=20\,cm,\] \[m=2\] For real image; \[m=-2,\] By using \[m=\frac{f}{f-u}\],   \[-2=\frac{-20}{-20-u}\Rightarrow u=-30\,cm\] For virtual image; \[m=+2\] So, \[+2=\frac{-\,20}{-20-u}\Rightarrow u=-10\,cm\]


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