All Problems

Electromagnetic Induction. Maxwells Equations

Problem 3.331

Two thin concentric wires shaped as circles with radii a and \(b\) lie in the same plane. Allowing for \(a \ll b,\) find: (a) their mutual inductance; (b) the magnetic flux through the surface enclosed by the outside wire, when the inside wire carries a current \(I\).

Reveal Answer
 (a) L121/2μ0πa2/b; (b) Φ21=1/2μ0πa2I/b . \text { (a) } L_{12} \approx 1 / 2 \mu_{0} \pi a^{2} / b ; \text { (b) } \Phi_{21}=1 / 2 \mu_{0} \pi a^{2} I / b \text { . }