How are wavelength and frequency related?

They are linked by the wave equation c = λ·f, where c is the speed of light (about 2.998×10⁸ m/s in vacuum), λ the wavelength, and f the frequency. Because c is constant, longer wavelengths mean lower frequencies and vice versa — they are inversely proportional.

How is photon energy calculated?

Photon energy follows the Planck relation E = h·f, equivalently E = h·c/λ, where h is Planck's constant (6.626×10⁻³⁴ J·s). Shorter wavelengths carry more energy per photon, which is why ultraviolet, X-rays, and gamma rays are ionising while radio waves are not.

What are the main spectrum bands?

From longest to shortest wavelength: radio, microwave, infrared, visible light, ultraviolet, X-rays, and gamma rays. They form a continuous spectrum; the boundaries are conventions rather than sharp lines, and adjacent bands overlap in practice.

Why is visible light such a tiny part of the spectrum?

Visible light spans only about 400 to 700 nanometres, a narrow slice between infrared and ultraviolet. Human eyes evolved to detect the wavelengths the Sun emits most strongly and that pass through the atmosphere and water, which is a very small fraction of the full range.

Are the band boundaries exact?

No. The divisions are conventional and vary slightly between sources, and neighbouring bands overlap — for example, the line between far-infrared and microwave, or between hard X-rays and gamma rays, is defined more by how the radiation is produced than by a precise wavelength.

Electromagnetic Spectrum Reference

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The electromagnetic spectrum is a single continuum of radiation, from kilometre-long radio waves to gamma rays smaller than an atomic nucleus. This reference lists every band with its wavelength and frequency range and includes a converter that links wavelength, frequency, and photon energy.

How it works

All electromagnetic radiation travels at the speed of light in vacuum, so wavelength and frequency are tied together by the wave equation:

c = λ · f

where c ≈ 2.998×10⁸ m/s. Rearranging gives f = c/λ. The energy carried by a single photon comes from the Planck relation:

E = h · f = h · c / λ

with Planck’s constant h = 6.626×10⁻³⁴ J·s. Dividing by 1.602×10⁻¹⁹ converts joules to electronvolts. Enter any wavelength or frequency and the tool computes all three quantities and identifies the band.

Reading the spectrum

The bands run, from long wavelength to short: radio, microwave, infrared, visible, ultraviolet, X-rays, and gamma rays. As wavelength shortens, frequency and photon energy rise. Below roughly 10 eV (the ultraviolet edge) photons become energetic enough to ionise atoms, which is why UV, X-rays, and gamma rays are hazardous while radio and microwaves are not.

Example and notes

Green light at 550 nm has a frequency of c/λ ≈ 5.45×10¹⁴ Hz and a photon energy of about 2.25 eV — squarely in the visible band. A 2.45 GHz microwave oven, by contrast, uses a wavelength of about 12 cm. Band boundaries are conventions and overlap in practice, so treat the ranges as approximate guides rather than sharp cut-offs.