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JEE Main & Advanced Physics Ray Optics Question Bank Refraction at Curved Surface

  • question_answer
    A thin lens made of glass of refractive index m = 1.5 has a focal length equal to 12 cm in air.  It is now immersed in water \[\left( \mu \,=\,\frac{4}{3} \right)\].  Its new focal length is        [UPSEAT 2002]

    A)            48 cm                                      

    B)            36 cm

    C)            24 cm                                      

    D)            12 cm

    Correct Answer: A

    Solution :

               \[{{f}_{w}}=4\times {{f}_{a}}=4\times 12=48\ cm.\]


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