$word_{count}$: 200

De Broglie wavelength: lambda = $\frac{h}{mv}$ = $\frac{h}{p}$. For electrons accelerated through V volts: lambda = 12.27/sqrt(V) angstroms. At same KE, lambda is proportional to 1/sqrt(m). At same momentum, lambda is the same regardless of mass. Connection to Bohr model: standing wave condition 2pir = n*lambda gives Bohr's L = $\frac{nh}{2*pi}$. This provided physical justification for Bohr's arbitrary quantisation postulate. De Broglie wavelength is significant only for microscopic particles (electrons: lambda ~ 1 A at 150 V). For macroscopic objects (cricket ball), lambda ~ 10^-34 m — undetectable. Davisson-Germer experiment confirmed electron diffraction from Ni crystal, validating de Broglie's hypothesis. Thomson and Davisson received Nobel Prizes for demonstrating particle and wave nature of electrons respectively. Wave-particle duality: matter shows both particle and wave behaviour, with one dominating depending on the experiment.