An α-particle, a proton and an electron have the same kinetic energy. Let their de Broglie wavelengths be λ₁, λ₂ and λ₃, respectively. Which relation is correct?
Options

Question

An α-particle, a proton and an electron have the same kinetic energy. Let their de Broglie wavelengths be λ₁, λ₂ and λ₃, respectively. Which relation is correct?

G1 Physics · Accepted Answer

For equal kinetic energy, λ = h/√(2mK), so λ ∝ 1/√m. Since mα > mₚ > mₑ, the wavelength order is λ₁ < λ₂ < λ₃. Correct answer: B.