electromagnetic radiation

American  

noun

Physics.

1. radiation consisting of electromagnetic waves, including radio waves, infrared, visible light, ultraviolet, x-rays, and gamma rays.

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electromagnetic radiation British  

noun

1. radiation consisting of self-sustaining oscillating electric and magnetic fields at right angles to each other and to the direction of propagation. It does not require a supporting medium and travels through empty space at the speed of light See also photon

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electromagnetic radiation Scientific  

1. Energy in the form of transverse magnetic and electric waves. In a vacuum, these waves travel at the speed of light (which is itself a form of electromagnetic radiation). The acceleration of electric charges (such as alternating current in a radio transmitter) gives rise to electromagnetic radiation. Other common examples of electromagnetic radiation are x-rays, microwaves, and radio waves. A single unit, or quantum, of electromagnetic radiation is called a photon.

2. See also electromagnetism polarization

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electromagnetic radiation Cultural  

1. Any type of electromagnetic wave.

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Closer Look

In the nineteenth century, physicists discovered that a changing electric field creates a magnetic field and vice versa. Thus a variation in an electric field (for example, the changing field created when a charged particle such as an electron moves up and down) will generate a magnetic field, which in turn induces an electric field. Equations formulated by James Clerk Maxwell predicted that these fields could potentially reinforce each other, creating an electromagnetic ripple that propagates through space. In fact, visible light and all other forms of electromagnetic radiation consist exactly of such waves of mutually reinforcing electric and magnetic fields, traveling at the speed of light. The frequency of the radiation determines how it interacts with charged particles, especially with the electrons of atoms, which absorb and reemit the radiation. The energy of the electromagnetic radiation is proportional to its frequency: the greater the frequency of the waves, the greater their energy. Electromagnetic radiation can also be conceived of as streams of particles known as photons. The photon is the quantum (the smallest possible unit) of electromagnetic radiation. In quantum mechanics, all phenomena in which charged particles interact with one another, as in the binding of protons and electrons in an atom or the formation of chemical bonds between atoms in a molecule, can be understood as an exchange of photons by the charged particles.

Etymology

Origin of electromagnetic radiation

First recorded in 1950–55

Example Sentences

Critics built a website that argued, among other things, that the project would unleash dangerous electromagnetic radiation.

From Salon • Apr. 27, 2026

The ranges allowed are narrow, far more restrictive than the sort of electromagnetic compatibility standards used on Earth, and unintended electromagnetic radiation can leak from electrical devices and systems on satellites.

From Salon • Apr. 4, 2025

The scientists found unintended electromagnetic radiation from almost all the V2 Starlink satellites observed.

From BBC • Sep. 18, 2024

The message is read using terahertz rays -- electromagnetic radiation that is invisible to the human eye.

From Science Daily • Mar. 18, 2024

In the room, a female graduate student evidently immune to the smell sat working on a spectrograph, an instrument for measuring electromagnetic radiation.

From "Big Science" by Michael Hiltzik

Related Words

• microwave