Example 10.7 A coil is wound on a torus as shown in Figures 10.14a and 10.14b. The coil consists of N turns,
carries a current I ¼ I0sinωt [A], and has an average radius r [m] (r b) as shown:
(a) Calculate the induced emf in the coil. What is the meaning of this emf?
(b) Show that the induced emf is proportional to the inductance of the coil.
(c) Suppose the permeability of the torus is very large. What is the induced emf in the coil?