# Helmholtz coils

## Helmholtz coils

A pair of flat circular coils with equal numbers of turns and equal diameters, arranged with a common axis, and connected in series to have a common current (see illustration). The purpose of the arrangement is to obtain a magnetic field that is more nearly uniform than that of a single coil without the use of a long solenoid. The optimum arrangement is that in which the distance between the two coils is equal to the radius of one of the coils.

Helmholtz coils separated by distance r, resulting in a nearly uniform field of point P

## Helmholtz coils

[′helm‚hōlts ‚kȯilz]
(electromagnetism)
A pair of flat, circular coils having equal numbers of turns and equal diameters, arranged with a common axis, and connected in series; used to obtain a magnetic field more nearly uniform than that of a single coil.
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References in periodicals archive ?
Kilaneh first computed and verified the magnetic field distribution caused by Helmholtz coils through numerical methods.
2006) Visualisation of magnetic fields generated by Helmholtz coils.
2 cm), a stop-watch timer, a thin string, a DC low voltage source, a set of Helmholtz coils of radius of 14.
This condition is nearly met because Helmholtz coils produce almost uniform field over a region much larger than the size of the magnet around the center of the coils.
In this method an externally controlled uniform magnetic field of a Helmholtz coil is applied parallel to the horizontal component of the Earth's field.
A Helmholtz coil set was placed around the magnet, with its symmetry axis parallel to the Earth's field and with the magnet at its center.
With an exposure level set at 1 mT, the heat dissipation from each of the Helmholtz coils is < 8 W of power.
Key words: Helmholtz coils, uniform magnetic field, COMSOL simulation, magnetic measurements
Helmholtz coils in one axis are consisted from two identical coils with defined radius R.
For the exact calculation of magnetic induction value in any point inside Helmholtz coils it is necessary to use Bessel functions.
We can use also this substitution: the center of Helmholtz coils is placed in distance x, which is equal to R/2.
Orthogonal Helmholtz coils provide the magnetic bias and saturating fields required for the measurement.

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