Photon energy calculator
Photon energy is Planck constant times frequency, and both h and c are exact, so this conversion is exact too.
Photon energy
2.254 258 2eV
- Photon energy
- 3.6117197e-19
- Frequency
- 545 077 200 000 000 Hz
- Momentum
- 1.20474e-27 kg m/s
- Energy per mole of photons
- 217.503 kJ/mol
Show the working
- Wavelength = 550
- m = 550 * 1e-9 = 0.000 000 55
- Frequency = c / 0.000 000 55 = 545 077 000 000 000
- Photon energy = h * 545 077 000 000 000 = 3.61172e-19
- Photon energy = 3.61172e-19 / qe = 2.254 26
- Momentum = h / 0.000 000 55 = 1.20474e-27
- Energy per mole of photons = 3.61172e-19 * NA / 1000 = 217.503
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- E = h c / lambda
- p = h / lambda
- E in eV = 1239.84 / lambda in nm
Green light at 550 nm carries 2.25 eV. Visible light spans roughly 1.65 to 3.26 eV.
The 1239.84 eV nm constant is exact under the 2019 SI, since both h and c are defined values.