Interactive Simulator · Quantum physics

The energy and momentum of a photon

Light comes in quanta called photons. A photon's energy is E = hf = hc/λ, and its momentum is p = E/c = h/λ. Shorter wavelength means higher frequency, more energy, and more momentum. Tune the wavelength and watch all four values change together.

Mission Tune the wavelength to make an ultraviolet photon with energy above 3.0 eV. Streak 0Best 0
Compared with a red photon, a blue (higher-frequency) photon has:
wavelength λ500 nm
frequency f = c/λ6.00 × 10¹⁴ Hz
energy E = hf2.48 eV
energy E (joules)3.97 × 10⁻¹⁹ J
momentum p = h/λ1.33 × 10⁻²⁷ N s
Visible light spans about 400 nm (violet) to 700 nm (red).