A solid cylinder of permanent-magnet material has radius and length

PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Magnetic materials · Magnetic materials

Electricity, Magnetism and Electromagnetism, Ch Magnetisation, bound currents and the auxiliary field H

Problem

A solid cylinder of permanent-magnet material has radius

8.0\,\mathrm{mm}

and length

5.0\,\mathrm{cm}

. Take the

z

axis along the axis of the cylinder. The cylinder is uniformly magnetised along its axis,

\mathbf{M} = M\hat{\mathbf{z}}

with

M = 1.2\times10^{5}\,\mathrm{A\,m^{-1}}

, and there is no free current anywhere. ((a)) Find the magnitude of the bound surface current per unit length on the curved side, and state the sense in which it flows. ((b)) Find the magnitude of the bound surface current per unit length on each flat end. ((c)) Find the total bound current that flows once round the curved side, that is the current that a single equivalent solenoid winding of this length would have to carry in total. ((d)) Find the magnitude of the bound volume current density inside the material.

Related theory

Magnetic materials

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