Photon Energy and Momentum Calculator
Connects a photon’s colour to its energy and momentum.
Photon energy
— eV
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
In joules —
Wavelength — nm
Frequency — THz
Momentum — kg·m/s
The formula
E = h f = h c ÷ λ p = h ÷ λ = E ÷ c
h is the Planck constant and c the speed of light, both exact by definition of the SI, as is the electronvolt. The wavelength is the one in a vacuum.
What to watch out for
A handy form: energy in eV is about 1,240 divided by the wavelength in nm.
Frequently Asked Questions
What is the energy of a 550 nm photon?
2.254 eV, or 3.612×10^-19 J.
What is its momentum?
1.205×10^-27 kg·m/s. Light pushes, but very gently.