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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 .
Eddy currents in conductors of non-zero resistivity generate heat as well as electromagnetic forces. The heat can be used for induction heating. The electromagnetic forces can be used for levitation, creating movement, or to give a strong braking effect. Eddy currents can also have undesirable effects, for instance power loss in transformers.
Using an electroscope to show electrostatic induction. The device has leaves/needle that become charged when introducing a charged rod to it. The leaves bend the leave/needle, and the stronger the static introduced, the more bending occurs. However, the induction effect can also be used to put a net charge on an object.
Disk electromagnetic brakes are used on vehicles such as trains, and power tools such as circular saws, to stop the blade quickly when the power is turned off.A disk eddy current brake consists of a conductive non-ferromagnetic metal disc attached to the axle of the vehicle's wheel, with an electromagnet located with its poles on each side of the disk, so the magnetic field passes through the ...
Applications range from the use of large inductors in power supplies, which in conjunction with filter capacitors remove ripple which is a multiple of the mains frequency (or the switching frequency for switched-mode power supplies) from the direct current output, to the small inductance of the ferrite bead or torus installed around a cable to ...
A rationalization of the triboelectric series is that different members have different work functions, so electrons can go from the material with a small work function to one with a large. [37] The potential difference between the two materials is called the Volta potential , also called the contact potential .
Radio-frequency induction (RF induction) is the use of a radio frequency magnetic field to transfer energy by means of electromagnetic induction in the near field. A radio-frequency alternating current is passed through a coil of wire that acts as the transmitter , and a second coil or conducting object, magnetically coupled to the first coil ...
In inductive coupling (electromagnetic induction [57] [77] or inductive power transfer, IPT), power is transferred between coils of wire by a magnetic field. [16] The transmitter and receiver coils together form a transformer. [16] [57] An alternating current (AC) through the transmitter coil (L1) creates an oscillating magnetic field (B) by ...