The figure below shows a doughnut-shaped toroidal solenoid, tightly wound with N turns of wire carrying a current I. 3. (10 points) Use Amperes Law to find the magnetic field inside the toroid. include a diagram of the toroid showing the Amperian loop you used. Your result should 4. (10 points) Determine the self-inductance of the toroidal solenoid with cross-sectional area A and mean radius r, closely wound with N turns of wire on a nonmagnetic core. (Assume that B is uniform across a cross-section). Note that the magnetic field of a toroid is Number of turns = N (only a few are shown) B = 2 (1)