A closely wound circular coil with a diameter of 3.95 cm has 500 turns and carries a current of 0.540 A.

Question

a) What is the magnitude of the magnetic field at the center of the coil?

The correct answer is .00859

by using (mu_0*N*I)/2r

b)What is the magnitude of the magnetic field at a point on the axis of the coil 8.00 cm from its center?

I'm keep getting the wrong answer

Answer 1

According to the source listed below the equation is as follows;

B=mu0NI/h

h=height of winding.

I reversed the answer you gave and got an answer of 19.7 windings/meter.

According to the second source it does not have to be longer than a length of one forth of a meter if the windings do not overlap. That is 2000 windings per meter.

There is either something missing of something missing outside of the conventional thinking. You will have to ask your professor.