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Electromagnetic or magnetic induction is the production of an electromotive force (emf) across an electrical conductor in a changing magnetic field. Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction .
Faraday's law of induction (or simply Faraday's law) is a law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (emf). This phenomenon, known as electromagnetic induction , is the fundamental operating principle of transformers , inductors , and many types of electric ...
Richard Feynman's Lectures on Physics also include a volume on electromagnetism that is available to read online for free, through the California Institute of Technology. In addition, there are popular physics textbooks that include electricity and magnetism among the material they cover, such as David Halliday and Robert Resnick 's ...
In electromagnetism, Ørsted's law, also spelled Oersted's law, is the physical law stating that an electric current induces a magnetic field. [ 2 ] This was discovered on 21 April 1820 by Danish physicist Hans Christian Ørsted (1777–1851), [ 3 ] [ 4 ] when he noticed that the needle of a compass next to a wire carrying current turned so ...
The volume charge density ρ is the amount of charge per unit volume (cube), surface charge density σ is amount per unit surface area (circle) with outward unit normal nĚ‚, d is the dipole moment between two point charges, the volume density of these is the polarization density P.
Aluminium ring moved by electromagnetic induction, thus demonstrating Lenz's law. Experiment showing Lenz's law with two aluminium rings on a scales-like device set up on a pivot so as to freely move in the horizontal plane. One ring is fully enclosed, while the other has an opening, not forming a complete circle.
In electromagnetism, Jefimenko's equations (named after Oleg D. Jefimenko) give the electric field and magnetic field due to a distribution of electric charges and electric current in space, that takes into account the propagation delay (retarded time) of the fields due to the finite speed of light and relativistic effects.
In three dimensions, the derivative has a special structure allowing the introduction of a cross product: = + = + from which it is easily seen that Gauss's law is the scalar part, the Ampère–Maxwell law is the vector part, Faraday's law is the pseudovector part, and Gauss's law for magnetism is the pseudoscalar part of the equation.