What is pole strength of a bar magnet? Is it the same as the dipole moment?
We know that a bar magnet when placed in a magnetic field experiences a torque given by
where M is the magnetic dipole moment
The moment of a couple with arm length d is given by
Equating the above expressions we can see that,
Let us say,
On comparing the above expression to the force on a charge due to electric field E, , we can say,
with analogy from electrostatics,pole strength is the equivalent of electric charge. Pole strength is NOT the same as dipole moment.