A torus from annealed iron has an inner radius of 2.0 cm and an outer radius of 2.4 cm. Assume the permeability of annealed iron is 2*10^-4 WB/At-m.
a) Calculate the reluctance of the torus. calculate the length of the torus based on the average radius.
b) A 400 turn coil is wrapped on the torus described above, and a current of 2.5 A is in the coil, find the flux density in the torus.