• $summary_{type}$: concept
• $word_{count}$: 180

de Broglie (1924) proposed that every moving particle has wave nature with wavelength λ = $\frac{h}{p}$ = $\frac{h}{mv}$. For a particle with kinetic energy KE: λ = h/$\sqrt{2mKE}$. For a charged particle through potential V: λ = h/$\sqrt{2mqV}$. Quick formulas: electron λ = 12.27/√V Å, proton λ = 0.286/√V Å, alpha particle λ = 0.101/√V Å. Critical comparisons at the same KE: lighter particles have longer wavelengths (λ ∝ 1/√m). At the same momentum: all particles have the same wavelength. At the same speed: lighter particles have longer wavelengths (λ ∝ 1/m). Thermal de Broglie wavelength: λ = h/$\sqrt{3mkT}$. The connection to Bohr model: 2πr = nλ (standing wave condition gives angular momentum quantization). Davisson-Germer experiment (1927) confirmed the hypothesis by observing electron diffraction from nickel crystal at 54 V (λ_measured = 1.65 Å ≈ λ_predicted = 1.67 Å).