Helmholtz coil
noun
Helm·holtz coil
ˈhel|mˌhōlts,
ˈheu̇|
: one of two equal parallel coaxial circular coils in series that are separated from each other by a distance equal to the radius of one coil for producing an approximately uniform magnetic field in the space between the coils
Word History
Etymology
after Hermann L.F. von Helmholtz †1894 German physicist