# electrodynamics

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## electrodynamics,

study of phenomena associated with charged bodies in motion and varying electric and magnetic fields (see chargecharge,
property of matter that gives rise to all electrical phenomena (see electricity). The basic unit of charge, usually denoted by e, is that on the proton or the electron; that on the proton is designated as positive (+e
; electricityelectricity,
class of phenomena arising from the existence of charge. The basic unit of charge is that on the proton or electron—the proton's charge is designated as positive while the electron's is negative.
); since a moving charge produces a magnetic fieldfield,
in physics, region throughout which a force may be exerted; examples are the gravitational, electric, and magnetic fields that surround, respectively, masses, electric charges, and magnets. The field concept was developed by M.
, electrodynamics is concerned with effects such as magnetismmagnetism,
force of attraction or repulsion between various substances, especially those made of iron and certain other metals; ultimately it is due to the motion of electric charges.
energy radiated in the form of a wave as a result of the motion of electric charges. A moving charge gives rise to a magnetic field, and if the motion is changing (accelerated), then the magnetic field varies and in turn produces an electric field.
, and electromagnetic inductioninduction,
in electricity and magnetism, common name for three distinct phenomena. Electromagnetic induction is the production of an electromotive force (emf) in a conductor as a result of a changing magnetic field about the conductor and is the most important of the
, including such practical applications as the electric generator and the electric motor. This area of electrodynamics, often known as classical electrodynamics, was first systematically explained by the physicist James Clerk Maxwell. Maxwell's equations, a set of differential equations, describe the phenomena of this area with great generality. A more recent development is quantum electrodynamics, which was formulated to explain the interaction of electromagnetic radiation with matter, to which the laws of the quantum theoryquantum theory,
modern physical theory concerned with the emission and absorption of energy by matter and with the motion of material particles; the quantum theory and the theory of relativity together form the theoretical basis of modern physics.
apply. The physicists P. A. M. Dirac, W. Heisenberg, and W. Pauli were the pioneers in the formulation of quantum electrodynamics. When the velocities of the charged particles under consideration become comparable with the speed of light, corrections involving the theory of relativityrelativity,
physical theory, introduced by Albert Einstein, that discards the concept of absolute motion and instead treats only relative motion between two systems or frames of reference.
must be made; this branch of the theory is called relativistic electrodynamics. It is applied to phenomena involved with particle accelerators and with electron tubes that are subject to high voltages and carry heavy currents.

## Electrodynamics

The study of the relations between electrical, magnetic, and mechanical phenomena. This includes considerations of the magnetic fields produced by currents, the electromotive forces induced by changing magnetic fields, the forces on currents in magnetic fields, the propagation of electromagnetic waves, and the behavior of charged particles in electric and magnetic fields. Classical electrodynamics deals with fields and charged particles in the manner first systematically described by J. C. Maxwell, whereas quantum electrodynamics applies the principles of quantum mechanics to electrical and magnetic phenomena. Relativistic electrodynamics is concerned with the behavior of charged particles and fields when the velocities of the particles approach that of light. Cosmic electrodynamics is concerned with electromagnetic phenomena occurring on celestial bodies and in space. See Electromagnetism, Quantum electrodynamics, Relativistic electrodynamics

## electrodynamics

[i‚lek·trō·dī′nam·iks]
(electromagnetism)
The study of the relations between electrical, magnetic, and mechanical phenomena.

## electrodynamics

the branch of physics concerned with the interactions between electrical and mechanical forces
References in periodicals archive ?
The qualitative and quantitative coincidence of the current density distributions measured and the calculated currents values for two different measurement methods allow to state the correct representation of the electrodynamic process model and the acceptability of the analytical dependences obtained.
Both specific electrodynamic problems generated by the expofunctional influences and mathematically simulated by the general wave equations regarding all components of the electromagnetic field vector intensities, are solved explicitly in detail.
Thereby Heitler [9] has shown that the quantized electrodynamic equations become identical with the original classical equations in which the electromagnetic potentials and currents merely become replaced by their quantum mechanical expectation values.
The device shown in Figure 1 has been termed an electrodynamic wheel (EDW).
The Electrodynamic QAL-991 PM Leak Detection and Measurement System features baghouse leak detection/emissions measurement from <1 mg/m3 to 100 mg/m3; fast, sensitive measurements; a measurement output not affected by dust accumulation on probe; and an automatic zero/span and self-contamination checks.
In 1965, professor Zenonas Vainoris initiated research in the field of electrodynamic slow-wave devices at Vilnius Gediminas Technical University.
Instron, a provider of testing equipment designed to evaluate mechanical properties of materials and components, has launched ElectroPuls, an electrodynamic test instrument for a wide range of biomedical testing requirements.
For that reason, electrodynamic (ED) shakers are used.
Instron has developed a new family of electrodynamic test instruments that can perform both static and dynamic testing--from simple tensile to high-frequency fatigue tests-on a variety of plastics, composites, and other materials and components.
An interdisciplinary team of researchers, led by Autumn, later confirmed speculation that the gecko's climbing ability depends on van der Waals forces, which are weak electrodynamic forces that operate over very small distances but bond to nearly any material.
The VFD also has an electrodynamic braking system that extends the disc life of the motor brake.

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