An electron initially moves with v = v₀î (v₀ > 0) in electric field E = -E₀î (E₀ > 0). If initial de Broglie wavelength is λ₀, its wavelength after time t is:
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An electron initially moves with v = v₀î (v₀ > 0) in electric field E = −E₀î (E₀ > 0). If initial de Broglie wavelength is λ₀, its wavelength after time t is:

G1 Physics · Accepted Answer

Electron charge is −e, so force qE = (−e)(−E₀î) = +eE₀î. Acceleration = eE₀/m and speed v(t) = v₀ + eE₀t/m. Since λ = h/(mv), λ(t) = λ₀v₀/v(t) = λ₀/[1 + eE₀t/(mv₀)]. Answer: C.