A Rowland ring is formed of ferromagnetic material. It is circular in cross section, with an inner radius of 5.0 cm and an outer radius of 6.0 cm, and is wound with 400 turns of wire.

(a) What current must be set up in the windings to attain a toroidal field of magnitude B0 = 0.20mT?

(b) A secondary coil wound around the toroid has 50 turns and resistance 8.0Ω. If, for this value of B0, we have BM = 800 B0, how much charge moves through the secondary coil when the current in the toroid windings is turned on?