I keep getting “Magnetic dipole moment” questions wrong in Magnetism & Matter. What's the trap?
reversing the magnetic moment direction because external field lines run north to south.
The usual trap: reversing the magnetic moment direction because external field lines run north to south. How to avoid it: dipole moment points S to N through the magnet. Go back to the definition — A bar magnet behaves like a magnetic dipole. Its moment points from south to north inside the magnet and determines the torque m x B in an external field.
Key point
Magnetic dipole moment
Common mistake
reversing the magnetic moment direction because external field lines run north to south.
Memory tip
dipole moment points S to N through the magnet.
Tap to watch or see it right here — the app stays open (it only opens a quick search if nothing embeddable is found).