Magnetic Field of Permanent Magnet

Imagine a typical compass needle magnet mounted on a pin that allows it to rotate freely in a plane. When held near a bar magnet, the needle will align itself along the lines of magnetic flux, but the poles of the compass will point in the opposite direction to the bar magnet's poles. For example, if the north pole of the bar magnet is pointing to the left, the compass needle will align itself parallel to the magnet, with its north pole pointing to the right. By moving the compass around the bar magnet, we observe the magnetic field of the large magnet is continuous, meaning the lines of magnetic flux form closed loops. The magnetic field is strongest inside the magnet, and the strongest external magnetic fields occur near the poles of the bar magnet. A magnetic north pole will attract the south pole of another magnet and repel a north pole. The direction of the magnetic field lines is conventionally taken to be outward from the north pole of the magnet and inward toward the south pole. Permanent magnets are made from ferromagnetic materials, and the magnetic field of a bar magnet results from the motion of negatively charged electrons within the material.