An air-filled toroidal solenoid has 400 turns of wire, a mean radius of 14.5cm , and a cross-sectional area of 4.00cm .
The first step in calculating the inductance of a coil is to invent an amount of current flowing through the coil. Suppose that a current of 6.00 is flowing through the wire of the toroid; what is the coefficient of 1/ in the proper expression for the magnetic field strength within the barrel of the toroid as a function of ?