For two point electric dipoles of moments and

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

The Boundary-Value Problem, Ch The magnetic multipole expansion and the magnetic scalar potential

Problem

For two point electric dipoles of moments

p_1

and

p_2

, both aligned along the line joining them, separated by a distance

z

along that line, the force between them (attractive when the dipoles point head-to-tail) is

F = \frac{6p_1p_2}{4\pi\varepsilon_0 z^4}.

((a)) Write down the analogous force between two point magnetic dipoles

m_1

m_2

coaxial and aligned head-to-tail, separated by

z

. ((b)) Two small coaxial bar magnets, each modelled as a point dipole with

m_1 = 1.0\,\mathrm{A\,m^2}

and

m_2 = 2.0\,\mathrm{A\,m^2}

, are aligned head-to-tail along their common axis,

z = 0.10\,\mathrm{m}

apart. Find the magnitude of the force between them.