Electromagnetic Spectrum
The continuous range of all frequencies and wavelengths of electromagnetic radiation, ordered from low-frequency radio waves to high-frequency gamma rays.
Governing formula
c = f λ, E = h f
SI unit
Hz (Frequency), m (Wavelength)
In depth
The spectrum comprises radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. All electromagnetic waves travel at the speed of light c ≈ 3 × 10⁸ m/s in vacuum.
Examples in the real world
Microwaves (~2.4 GHz) heating water molecules in food, visible light (~500 nm) stimulating human vision, and X-rays (~0.1 nm) penetrating soft tissue for medical imaging.