Photon Energy from Wavelength (E = hc/λ)
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Constants used — built into this formula, no need to enter
Planck constant · exactSpeed of light in vacuum · exactLearning zone
Combining E = hf with c = fλ gives the spectroscopist's favorite form. The product hc ≈ 1240 eV·nm is worth memorizing: a 620 nm red photon carries 2 eV, a 124 nm ultraviolet photon 10 eV, a 0.1 nm X-ray photon 12.4 keV. Silicon solar cells have a 1.1 eV band gap, so photons with wavelengths longer than about 1100 nm — a third of sunlight's energy — pass straight through and can never be harvested.
Photon Energy from Wavelength (E = hc/λ)
Where
- = Photon energy
- = Wavelength
Missing one of these? Work it out first, then come back
- Photon energy — Photon Energy (E = hf), Photoelectric Effect
- Wavelength — Photon Momentum (p = h/λ), Wave Speed (v = fλ)