Question

What is the far axial magnetic field of a solenoid expressed in terms of its total magnetic moment \[m\]?

Options

• \[B=\frac{\mu_0}{4\pi}\cdot\frac{2r^3}{m}\]

• \[B=\frac{\mu_0}{4\pi}\cdot\frac{2m}{r^2}\]

• \[B=\frac{\mu_0}{4\pi}\cdot\frac{2m}{r^3}\]

• \[B=\frac{\mu_0}{4\pi}\cdot\frac{m}{r^3}\]

Answer 1

The far axial field is \[B=\frac{\mu_0}{4\pi}\cdot\frac{2m}{r^3}\]. It has the same form as the far axial field of a bar magnet.