Toroidal inductors and transformers

Toroidal inductors and transformers are a kind of electronic component. They typically consist of a circular, ring-shaped magnetic centre. The magnet is usually considered a monopole, although the central axis will have a dipole, and have the advantage of being wound continuously in a single direction, thus there is no inductive interference between windings as in a solenoid that is wound back and forth.

 References 

Other websites
 Approximate inductance of a toroid includes formula, but assumes circular windings

Category:Transformers (electrical)
Category:Magnetism