Electromagnetic spectrum
The full range of electromagnetic radiation, from radio to gamma rays.
The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. It is divided into separate bands, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. The spectrum's discovery and understanding emerged through the work of multiple scientists over centuries, linking light to electromagnetism and revealing waves of all frequencies.
- field
- Physics, Electromagnetism
- known_for
- Full range of electromagnetic radiation, from radio waves to gamma rays
- key_discoverers
- Isaac Newton, James Clerk Maxwell, Heinrich Hertz, Wilhelm Röntgen, Paul Villard
Lore & Background
The study of electromagnetism began in 1820 when Hans Christian Ørsted discovered that electric currents produce magnetic fields. During the 1860s, James Clerk Maxwell developed equations predicting electromagnetic waves traveling at the speed of light, inferring that light itself is an electromagnetic wave.
Reader's Guide
The electromagnetic spectrum is fundamental to modern science and technology. Its discovery unified seemingly disparate phenomena—light, radio, X-rays—under a single electromagnetic theory. The spectrum's bands have distinct characteristics: radio waves have the longest wavelengths and lowest photon energy, while gamma rays have the shortest wavelengths and highest energy. Gamma rays, X-rays, and extreme ultraviolet are ionizing radiation, capable of ionizing atoms and causing chemical reactions; longer-wavelength radiation like visible light is non-ionizing. Spectroscopy, which separates waves by frequency, is used throughout most of the spectrum to study interactions with matter, with applications in astrophysics, such as detecting hydrogen's 21.12 cm radio wave. The spectrum's range extends from frequencies as low as about 1 kHz to as high as 2.9×10^27 Hz from astrophysical sources. The wave-particle duality, arising from Planck's and Einstein's work, remains a subject of debate. The spectrum enabled inventions like wireless telegraphy and radio, and radiography through X-rays.
Did You Know?
- Frequencies as high as 2.9×10^27 Hz have been detected from astrophysical sources.
More in Electromagnetism 1-21
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record