![]() Ĭoils can have more than one winding, insulated electrically from each other. A winding that has a single tap in the center of its length is called center-tapped. Windings may have additional electrical connections along their length these are called taps. The ends of the wire are brought out and attached to an external circuit. The winding is often wrapped around a coil form made of plastic or other material to hold it in place. In windings in which the turns touch, the wire must be insulated with a coating of nonconductive insulation such as plastic or enamel to prevent the current from passing between the wire turns. The hole in the center of the coil is called the core area or magnetic axis. The wire or conductor which constitutes the coil is called the winding. Windings and taps Diagram of typical transformer configurations The crosses are wires in which current is moving into the page the dots are wires in which current is emerging from the page. This drawing shows a cross section through the center of the coil. In a coil of multiple turns of wire the magnetic field of the turns adds in the center of the coil, creating a strong field. There are many different types of coils used in electric and electronic equipment. The end of a magnetic core from which the field lines emerge is defined to be the North pole. If the fingers of the right hand are wrapped around the magnetic core of a coil in the direction of conventional current through the wire, the thumb will point in the direction the magnetic field lines pass through the coil. The direction of the magnetic field produced by a coil can be determined by the right hand grip rule. The induced voltage can be increased by winding the wire into a coil because the field lines intersect the circuit multiple times. Conversely, a changing external magnetic flux induces a voltage in a conductor such as a wire, due to Faraday's law of induction. The greater the number of turns of wire, the stronger the field produced. The magnetic fields generated by the separate turns of wire all pass through the center of the coil and add ( superpose) to produce a strong field there. The advantage of using the coil shape is that it increases the strength of the magnetic field produced by a given current. Either an electric current is passed through the wire of the coil to generate a magnetic field, or conversely, an external time-varying magnetic field through the interior of the coil generates an EMF ( voltage) in the conductor.Ī current through any conductor creates a circular magnetic field around the conductor due to Ampere's law. Electromagnetic coils are used in electrical engineering, in applications where electric currents interact with magnetic fields, in devices such as electric motors, generators, inductors, electromagnets, transformers, and sensor coils. The magnetic field lines ( green) of a current-carrying loop of wire pass through the center of the loop, concentrating the field thereĪn electromagnetic coil is an electrical conductor such as a wire in the shape of a coil ( spiral or helix). For other uses, see Winding (disambiguation). R 1 and R 2 are the resistances of the two coils."Winding" redirects here.L 1 and L 2 are the inductances of the two Helmholtz coils, and. ![]() ω is the angular frequency or ω = 2 πf,.When the pair of two electromagnetics of a Helmholtz coil carry an equal electric current in the opposite direction, it is known as anti-Helmholtz coil, which creates a region of nearly uniform magnetic field gradient, and is used for creating magnetic traps for atomic physics experiments.Ī beam of cathode rays in a vacuum tube bent into a circle by a Helmholtz coil Description Ī Helmholtz pair consists of two identical circular magnetic coils that are placed symmetrically along a common axis, one on each side of the experimental area, and separated by a distance h Besides creating magnetic fields, Helmholtz coils are also used in scientific apparatus to cancel external magnetic fields, such as the Earth's magnetic field. It consists of two electromagnets on the same axis, carrying an equal electric current in the same direction. Two circular coil device which creates a homogeneous magnetic field A Helmholtz coil Helmholtz coil schematic drawingĪ Helmholtz coil is a device for producing a region of nearly uniform magnetic field, named after the German physicist Hermann von Helmholtz.
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