Description
A Helmholtz pair consists of two identical circular magnetic coils that are placed symmetrically one on each side of the experimental area along a common axis, and separated by a distance equal to the radius of the coil. Each coil carries an equal electrical current flowing in the same direction.
Setting, which is what defines a Helmholtz pair, minimizes the nonuniformity of the field at the center of the coils, in the sense of setting (meaning that the first nonzero derivative is as explained below), but leaves about 7% variation in field strength between the center and the planes of the coils. A slightly larger value of reduces the difference in field between the center and the planes of the coils, at the expense of worsening the field’s uniformity in the region near the center, as measured by .
In some applications, a Helmholtz coil is used to cancel out the Earth's magnetic field, producing a region with a magnetic field intensity much closer to zero.
Read more about this topic: Helmholtz Coil
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