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Question 37 of 42

Q.If the momentum of an electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%, then the initial momentum of the electron was

(a) 400 P
(b) 200 P
(c) 100 P
(d) P/100
West Bengal WbchseWest Bengal HS (WBCHSE) Board 2025MCQ· 1mImportance★★★★★
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Since λ ∝ 1/p, a fractional change in p produces an equal fractional change in λ; solving for the initial momentum from the 0.5% wavelength change gives 200P.

De Broglie wavelength: λ=h/p\lambda = h/p. Differentiating (magnitudes):

∣Δλ∣λ=∣Δp∣p\dfrac{|\Delta\lambda|}{\lambda}=\dfrac{|\Delta p|}{p} …

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