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JEE Main 2025 (8 Apr, Shift 2) · Matter Waves: de Broglie Wavelength

Matter Waves: de Broglie Wavelength question from JEE Main 2025 (8 Apr, Shift 2)

Q47JEE Main 2025 · 8 APR · SHIFT 2Difficult

Matter Waves: de Broglie Wavelength

An electron is released from rest near an infinite non-conducting sheet of uniform charge density '−σ-\sigma'. The rate of change of de-Broglie wave length associated with the electron varies inversely as nth power of time. The numerical value of n is _____.

Numerical answer type. Work it out, then open the answer.

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Answer: 2

  1. Infinite sheet: uniform field E=σ2ε0E = \dfrac{\sigma}{2\varepsilon_0}, so constant force eEeE.
  2. From rest: p=eEtp = eEt, λ=heEt\lambda = \dfrac{h}{eEt}.
  3. dλdt=−heEt2∝t−2\dfrac{d\lambda}{dt} = -\dfrac{h}{eEt^2} \propto t^{-2}
  4. Answer: n=2n = 2
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