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JEE Main & Advanced JEE Main Paper Phase-I (Held on 09-1-2020 Evening)

  • question_answer
    An electron of mass m and magnitude of charge \[\left| e \right|\]initially at rest gets accelerated by a constant electric field E. The rate of change of de-Broglie wavelength of this electron at time t ignoring relativistic effects is [JEE MAIN Held on 09-01-2020 Evening]

    A) \[-\frac{h}{|e|E\sqrt{t}}\]

    B) \[\frac{-h}{|e|E{{t}^{2}}}\]

    C) \[\frac{|e|Et}{h}\]

    D) \[-\frac{h}{|e|Et}\]

    Correct Answer: B

    Solution :

    \[V=\frac{eE}{m}t\] \[\lambda =\frac{h}{eEt}\] \[\frac{d\lambda }{dt}=\frac{-h}{eE{{t}^{2}}}\]


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