Use three different ways to illustrate how two very long magnets attract or repel each other.
Hints:
In vector form, M to J-m: The magnetic field (B) produced by the magnetic moment (J-m) of bar 1 exerts a force on the magnetic moment (J-m) of bar 2.
In scalar form, M to rho-m: The magnetic charge (rho-m) of bar 1 exerts a force on the magnetic charge (rho-m) of bar 2.
In terms of the total energy of the magnetic field (B), when two bars are separated, will the energy increase or decrease?