JEE Main & Advanced Physics Ray Optics Sample Paper Topic Test - Refraction of Light Through Curved Surfaces

  • question_answer
    A convex lens of focal length 15 cm placed coaxially in front of a convex mirror. The lens is 5 cm from apex of mirror. When an object is placed on the axis at a distance of 20 cm from the lens, it is found that image coincides with object, radius of curvature of mirror is

    A) 65 cm

    B) 60 cm   

    C) 55 cm 

    D) 75 cm

    Correct Answer: C

    Solution :

    [c] For lens, let image distance is v, then \[\frac{1}{v}-\frac{1}{-20}=\frac{1}{15}\] \[v=60cm\] Since object coincides with image, center of curvature of mirror must coincide with image of convex lens so that rays fall normally on mirror and then return along their original path \[R=60-5=55cm\].

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