Question

What is Toroid?

Answer

Toroid is a hollow circular ring on which a large number of turns of a wire is closely wound. It can be viewed as a solenoid which has been bent into a circular shape to close on itself. It is carrying a current I. We shall see that the magnetic field in the open space inside (point P) and exterior to the Toroid (point Q) is zero. The field inside the Toroid is constant in magnitude for the ideal Toroid of closely wound turns.