de Broglie wavelength
Definition
The de Broglie wavelength is the wavelength assigned to matter — every moving particle, from electrons to baseballs, has one, though only tiny particles show it.
Symbol: ·
Technical definition
λ = h/p = h/(mv). For an electron accelerated through 100 V (v ≈ 5.9×10⁶ m/s), λ ≈ 0.12 nm — comparable to atomic spacing, which is why electron microscopes resolve atoms.
Example
A 70 kg person walking at 1 m/s has λ = 6.63×10⁻³⁴/70 ≈ 9.5×10⁻³⁶ m — so absurdly small that no experiment could ever detect it.
Common confusion
Matter waves are not waves of stuff sloshing around. The de Broglie wavelength governs the probability pattern of where the particle will be found — electrons diffract like waves but still arrive as single particles.