Magnetic dipole consists to two unlike poles of equal strength and separated by a small distance.
The distance between the two poles of the bar is called magnetic length of the magnet. It is a vector directed from S-pole to N-Pole and represented by 2l.
Magnetic dipole is the product of the strength of either dipole (m) or the magnetic length (2l) of the magnet. It is represented by M.
It is vector quantity directed from South to North Poles.SI unit of M is ampere-meter2 or joule/tesla.