A particle of mass 1 mg has the same de Broglie wavelength as an electron of speed 3 × 10⁶ m/s. Find particle speed (mₑ = 9.1 × 10⁻³¹ kg).
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A particle of mass 1 mg has the same de Broglie wavelength as an electron of speed 3 × 10⁶ m/s. Find particle speed (mₑ = 9.1 × 10⁻³¹ kg).

G1 Physics · Accepted Answer

Equal λ means equal momentum: Mv = mₑvₑ. Particle mass M = 1 mg = 10⁻⁶ kg. Thus v = (9.1 × 10⁻³¹ × 3 × 10⁶)/(10⁻⁶) = 2.73 × 10⁻¹⁸ m/s. Answer: A.