Physics

Problem

Which of the following gives the magnitude of the magnetic field

B

at the centre of a circular coil of

N

closely packed turns, radius

r

, carrying current

I

? a)

B = \dfrac{\mu_0 I}{2 r}

B = \dfrac{\mu_0 N^2 I}{2 r}

B = \dfrac{\mu_0 N I}{2 r}

B = \dfrac{\mu_0 N I}{4 \pi r}