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JEE Main & Advanced Physics EM Waves Question Bank Mock Test - Electromagnetic Waves and Dual Nature

  • question_answer
    A plane em wave of wave intensity of \[10\,W/{{m}^{2}}\] strikes a small mirror of area 20\[c{{m}^{2}}\], held perpendicular to the approaching wave. The radiation force on the mirror will be

    A) \[6.6\times {{10}^{-11}}N\]     

    B) \[1.33\times {{10}^{-11}}N\]

    C) \[1.33\times {{10}^{-10}}N\]

    D) \[6.6\times {{10}^{-10}}N\]

    Correct Answer: C

    Solution :

    [c] Radiation force = Momentum transferred per second by electromagnetic wave to the mirror \[=\frac{2{{I}_{av}}A}{c}=\frac{2\times (10)\times (20\times {{10}^{-4}})}{(3\times {{10}^{8}})}=1.33\times {{10}^{-10}}N\]


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