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Electromagnetic radiation is commonly referred to as "light", EM, EMR, or electromagnetic waves. [ 2 ] The position of an electromagnetic wave within the electromagnetic spectrum can be characterized by either its frequency of oscillation or its wavelength.
Apr 10, 2022 · James Clerk Maxwell showed that whenever charged particles change their motion, as they do in every atom and molecule, they give off waves of energy. Light is one form of this electromagnetic radiation. The wavelength of light determines the color of visible radiation.
- Overview
- Light as electromagnetic radiation
- Electric and magnetic fields
- Maxwell’s equations
In spite of theoretical and experimental advances in the first half of the 19th century that established the wave properties of light, the nature of light was not yet revealed—the identity of the wave oscillations remained a mystery. This situation dramatically changed in the 1860s when the Scottish physicist James Clerk Maxwell, in a watershed the...
In spite of theoretical and experimental advances in the first half of the 19th century that established the wave properties of light, the nature of light was not yet revealed—the identity of the wave oscillations remained a mystery. This situation dramatically changed in the 1860s when the Scottish physicist James Clerk Maxwell, in a watershed the...
The subjects of electricity and magnetism were well developed by the time Maxwell began his synthesizing work. English physician William Gilbert initiated the careful study of magnetic phenomena in the late 16th century. In the late 1700s an understanding of electric phenomena was pioneered by Benjamin Franklin, Charles-Augustin de Coulomb, and others. Siméon-Denis Poisson, Pierre-Simon Laplace, and Carl Friedrich Gauss developed powerful mathematical descriptions of electrostatics and magnetostatics that stand to the present time. The first connection between electric and magnetic effects was discovered by Danish physicist Hans Christian Ørsted in 1820 when he found that electric currents produce magnetic forces. Soon after, French physicist André-Marie Ampère developed a mathematical formulation (Ampère’s law) relating currents to magnetic effects. In 1831 the great English experimentalist Michael Faraday discovered electromagnetic induction, in which a moving magnet (more generally, a changing magnetic flux) induces an electric current in a conducting circuit.
Faraday’s conception of electric and magnetic effects laid the groundwork for Maxwell’s equations. Faraday visualized electric charges as producing fields that extend through space and transmit electric and magnetic forces to other distant charges. The notion of electric and magnetic fields is central to the theory of electromagnetism, and so it requires some explanation. A field is used to represent any physical quantity whose value changes from one point in space to another. For example, the temperature of Earth’s atmosphere has a definite value at every point above the surface of Earth; to specify the atmospheric temperature completely thus requires specifying a distribution of numbers—one for each spatial point. The temperature “field” is simply a mathematical accounting of those numbers; it may be expressed as a function of the spatial coordinates. The values of the temperature field can also vary with time; therefore, the field is more generally expressed as a function of spatial coordinates and time: T(x, y, z, t), where T is the temperature field, x, y, and z are the spatial coordinates, and t is the time.
In the early 1860s, Maxwell completed a study of electric and magnetic phenomena. He presented a mathematical formulation in which the values of the electric and magnetic fields at all points in space can be calculated from a knowledge of the sources of the fields. By Faraday’s time, it was known that electric charges are the source of electric fie...
Electromagnetic radiation can essentially be described as photon streams. These photons are strictly defined as massless, but have both energy and surprisingly, given their lack of mass, momentum, which can be calculated from their wave properties.
Apr 8, 2008 · Physics. Explainer: Understanding light and electromagnetic radiation. Here's a simple guide to the different types of electromagnetic energy that move as waves. The electromagnetic spectrum describes different types of radiation, from visible light to gamma rays and more. NASA's Imagine the Universe. By Janet Raloff. April 8, 2008 at 6:58 pm.
Oct 24, 2024 · Electromagnetic radiation, in classical physics, the flow of energy at the speed of light through free space or through a material medium in the form of the electric and magnetic fields that make up electromagnetic waves such as radio waves and visible light.
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Light is sometimes also known as visible light to contrast it from "ultraviolet light" and "infrared light". Other forms of electromagnetic radiation that are not visible to humans are sometimes also known informally as "light". Polychromatic light is described by many different frequencies.
