de Broglie Wavelength Calculator

Kaava

How this is calculated

Louis de Broglie proposed that every moving particle has an associated wavelength λ = h/p, where h is the Planck constant (6.62607015 × 10⁻³⁴ J·s) and p is the particle momentum. This calculator lets you supply momentum two ways: either enter mass m (in kilograms) and velocity v (in metres per second), from which momentum is computed as p = m·v, or enter the momentum p directly (in kg·m/s) using the mode selector.

Once p is known, the wavelength follows as λ = h/p. The result is reported in metres and also converted to nanometres (1 m = 10⁹ nm) for convenience, since matter wavelengths of subatomic particles are typically far smaller than visible-light wavelengths. The computed momentum and the particle label you provide are shown alongside.

This uses the non-relativistic definition p = m·v, which is accurate when v is much less than the speed of light. At speeds approaching c the relativistic momentum p = γmv should be used instead. The calculator guards against division by zero: if momentum is zero (a particle at rest), no finite wavelength exists and you are prompted to enter valid values.