Electromagnetic spectrum

The full range of electromagnetic radiation, ordered by frequency or wavelength from radio waves to gamma rays. Its bands differ in wavelength and energy but share the same underlying electromagnetic nature.

Electromagnetic radiation: Energy transmitted through space as oscillating electric and magnetic fields or as photons. The spectrum is the complete range of this radiation, arranged by frequency or wavelength.
Maxwell's equations: Four equations describing how electric and magnetic fields are produced and how they change. They predict electromagnetic waves and their propagation through vacuum.
Radio astronomy: The study of celestial objects through the radio waves they emit or reflect. It uses the longest-wavelength region to investigate cosmic sources.
Radio wave: An electromagnetic wave in the low-frequency, long-wavelength region commonly used for communication and sensing. It occupies one end of the spectrum and overlaps in physical nature with all other bands.
Wavelength: The distance between successive matching points on a wave, such as adjacent crests. Wavelength provides one of the two standard ways to order spectrum bands.
Planck relation: The equation stating that a photon's energy equals Planck's constant multiplied by its frequency. It explains why high-frequency bands carry more energetic photons.
Infrared astronomy: The study of celestial objects using infrared radiation. Infrared observations reveal cool objects and sources hidden by dust.
Microwave: Electromagnetic radiation at frequencies above conventional radio waves and below infrared radiation. Its placement illustrates that named regions are subdivisions of a continuous spectrum.
Frequency: The number of cycles of a periodic signal that pass a point per unit time. Frequency orders the bands inversely to wavelength and directly to photon energy.
Electromagnetic radiation pressure: The pressure exerted when electromagnetic radiation transfers momentum to matter. It shows that every spectral band carries momentum as well as energy.

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