(i) Use Ampere’s law to determine the magnetic field in a densely wound toroidal solenoid with inner radius a, outer radius b, and N total turns. The cross section of the solenoid is a rectangle of width b-a and height h.
(ii) Show that your result from (i) agrees with the magnetic field for a straight solenoid in the limit a, b ? 8 with b - a and the linear density of turns fixed.