Convert wavelength to frequency and photon energy, or back, with c = fλ and E = hf, and see where the wave sits in the electromagnetic spectrum.
更新于 已验证的示例：6
550 nm is visible light (green): it oscillates at 545.08 THz and each photon carries 2.25426 eV.
c, h and e are exact in the 2019 SI (CODATA 2022).
Light and every other electromagnetic wave travel at c = 299,792,458 m/s in a vacuum, so wavelength and frequency fix each other through c = fλ. Each photon carries energy E = hf = hc/λ, where h is Planck's constant. Enter any one of the three and the calculator returns the other two, plus the wavenumber, the energy per mole of photons and the band of the spectrum.
Students use it for photon-energy problems, and radio and optics work uses it to move between frequency and wavelength. Green light at 550 nm has a frequency of 5.45 × 10¹⁴ Hz and 2.25 eV per photon; the 2.45 GHz wave in a microwave oven is 12.2 cm long.
Wavelengths are vacuum values: inside glass or water, divide by the refractive index, while the frequency stays the same. Band edges are conventions that differ slightly between sources.
核验来源：Python 3.8 decimal with exact SI c, h, e: f = c/λ, E = hc/λ/e = 2.2542582 eV
核验来源：Python 3.8 decimal: λ = 299792458/2.45e9 = 0.1223643 m
核验来源：Python 3.8 decimal: λ = hc/(13.6 e) = 91.16485 nm (the Lyman limit is 91.2 nm)
核验来源：c/f = 2.99792458 m exactly (c is defined)
Divide the speed of light by the wavelength: f = c/λ, with c = 299,792,458 m/s and λ in metres. For 550 nm green light, f = 299,792,458 ÷ 0.000000550 = 5.45 × 10¹⁴ Hz, or 545 THz. The reverse is λ = c/f: an FM station at 100 MHz has a wavelength of 3.00 m.
Multiply Planck's constant by the frequency, E = hf, or divide hc by the wavelength, E = hc/λ, with h = 6.62607015 × 10⁻³⁴ J·s. In electronvolts, E = 1239.84 ÷ λ in nanometres, so a 700 nm red photon carries 1.77 eV and a 400 nm violet one 3.10 eV. h and the electron charge have been exact in the SI since 2019, and c since 1983.
About 380 to 750 nanometres, from violet to red; this calculator uses those edges for the visible band. Sources put the red end anywhere from 700 to 780 nm because eye sensitivity fades gradually; ISO 21348 uses 380–760 nm. Photon energies across the range run from 3.26 eV at 380 nm down to 1.65 eV at 750 nm.
About 12 cm. Microwave ovens run at 2.45 GHz, a wavelength of 12.24 cm, and 2.4 GHz Wi-Fi is 12.49 cm; 5 GHz Wi-Fi is 6.00 cm. Each 2.45 GHz photon carries 0.0000101 eV, over 200,000 times less than a green-light photon and far below the 13.6 eV needed to ionise a hydrogen atom, so microwaves heat food without ionising it.
The number of waves per centimetre, 1/λ, quoted in cm⁻¹ in infrared and Raman spectroscopy. From nanometres, the wavenumber is 10,000,000 ÷ λ: 550 nm is 18,182 cm⁻¹. An infrared band at 3,000 cm⁻¹, where C–H bonds stretch, lies at 3.33 µm. Wavenumber is proportional to photon energy, which is why spectroscopists use it as an energy scale.
准确性取决于输入值和方法的假设。十进制运算使用50位有效数字，但估算、数值方法和源数据的精度可能较低；显示时的舍入并不能消除这些限制。 已按独立来源核验的计算示例：6。 例如，“Green light, 550 nm”根据Python 3.8 decimal with exact SI c, h, e: f = c/λ, E = hc/λ/e = 2.2542582 eV进行核验。
CODATA 2022 — c, h and e are exact in the SI; NASA Science — Tour of the electromagnetic spectrum (band names and ranges); ISO 21348:2007 — Definitions of solar irradiance spectral categories.
此计算器包含 6 个已解示例，答案来自独立来源。这些示例会在测试套件中运行，你也可以在此运行验证。
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