de Broglie Relation
The relation stating that every particle has an associated wavelength inversely proportional to its momentum.
Formula / equation
λ = h / mv
Unit
m
In depth
Proposed in 1924 and confirmed by the Davisson–Germer electron diffraction experiment, wave–particle duality explains why electrons form standing waves in orbitals and why only certain orbits are allowed. Because Planck's constant is tiny, macroscopic objects have wavelengths far too small to detect.
Examples in the real world
An electron accelerated through 100 V has λ ≈ 0.12 nm, comparable to atomic spacing — the basis of electron microscopy.