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JEE Main & Advanced Physics Wave Optics / तरंग प्रकाशिकी Question Bank EM Waves

  • question_answer
    The 21 cm radio wave emitted by hydrogen in interstellar space is due to the interaction called the hyperfine interaction is atomic hydrogen. the energy of the emitted wave is nearly                                         [CBSE PMT 1998]

    A)            \[{{10}^{-17}}\]Joule         

    B)            1 Joule

    C)            \[7\times {{10}^{-8}}\]Joule  

    D)            \[{{10}^{-24}}\]Joule

    Correct Answer: D

    Solution :

               \[E=\frac{hc}{\lambda }=\frac{6.6\times {{10}^{-34}}\times 3\times {{10}^{8}}}{21\times {{10}^{-2}}}\]= \[0.94\times {{10}^{-24}}\approx {{10}^{-24}}J\]


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