Question

Obtain an expression for magnetic induction along the axis of turoid

Answer 1

The formula for the magnitude of magnetic field inside a toroid is:

B=μoNI2πr

B=μoNI2πr

where NN is the number of turns threading a curve along, maybe, the axis of the toroid or along a field line inside the toroid. And II is the current in each turn. Now, if there are nn turns per unit length of this curve, then for the whole curve, which is a circle, I can write:

B=μo(2πrn)I2πr

B=μo(2πrn)I2πr

which is

B=μonI,

B=μonI,

but that's the magnitude of magnetic field inside a solenoid or should I say non-toroidal solenoid. Even more, it says that the magnetic field is constant inside the toroid? Or maybe not? Where am I going wrong? I know calculus only roughly. Thank you.