Question

Which expression gives the magnetic field at a point \(P\) on the axis of a circular current loop?

Options

• \(B=\frac{\mu_0 I R^2}{2(x^2+R^2)^{3/2}}\)

• \(B=\frac{\mu_0 I R}{2(x^2+R^2)^{3/2}}\)

• \(B=\frac{\mu_0 I R^2}{2(x^2+R^2)}\)

• \(B=\frac{\mu_0 I x^2}{2(x^2+R^2)^{3/2}}\)

Answer 1

Adding the axial components around the full circumference gives \(B=\frac{\mu_0 I R^2}{2(x^2+R^2)^{3/2}}\). This is the field anywhere on the axis of a current loop.