Toroid
A Toroid is a doughnut-shaped object enclosed by a torus. It has a ring-shaped surface generated by rotating a circle around an axis that does not intersect the circle. Usually, a toroid is composed of a coil of insulated wire in a donut shape (and is usually composed of iron or similar metals).Toroids are inductors in circuits. They are primarily used in low frequencies transception for the inductance properties needed. Toroids possess greater inductance properties and carry greater current than similarly constructed solenoids. Toroidal coils reduce resistance, due to diameter and number. In a toroid, magnetic fluxes are confined in the toroid's core.