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Question
CBSEENPH12040142

An electron of mass m with an initial velocity V = Voi^ (Vo>0) enters an electric field E = - Eo i^  (E0 constant >0) at t = 0. if λ0 is its de-Broglie wavelength initially, then its de-Broglie wavelength at time t is

  • λ01+eE0mV0t

  • λo1 + eE0mV0t

  • λ0

  • λ0t

Solution

A.

λ01+eE0mV0t

Initial de-Brogile wavelength

λ0 = hmV0 .... (i)

Acceleration of electron

a = eE0m  ( F- ma = eE0)Velocity  after time 't'V = V0+ eE0mtSo , λ = hmV = hmV0 + eE0mtSo, λ = hmV01+eE0mV0t = λ01 + eE0mV0t... (ii)Dividing eqs (ii) by (i)de - Broglie wavelength  λ = λ01+ eE0mV0 t