JEE Main & Advanced AIEEE Solved Paper-2004

  • question_answer
    A radiation of energy E falls normally on d perfectly reflecting surface. The momentum transferred to the surface is

    A) \[E/c\]                 

    B)        \[2E/c\]               

    C)        \[Ec\]                   

    D)        \[E/{{c}^{2}}\]

    Correct Answer: B

    Solution :

    Initial momentum of surface \[{{p}_{i}}=\frac{E}{c}\] where c = velocity of light (constant). Since, the surface is perfectly reflecting, so the same momentum will be reflected completely. Final momentum,\[{{p}_{f}}=\frac{E}{c}\]            (with negative value) \[\therefore \]Change in momentum \[\Delta p={{p}_{f}}-{{p}_{i}}=-\frac{E}{c}-\frac{E}{c}=-\frac{2E}{c}\] Thus, momentum transferred to the surface is \[\Delta p'=|\Delta p|=\frac{2E}{c}\]


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