Magnetic Field of a Bar Magnet

A bar magnet is a permanent magnet with a rectangular, cylindrical or similar shape with different magnetic properties at two ends, known as North and South poles.
Magnetic fields surround bar magnets and other magnetic materials, and the effect of these fields can be felt most strongly near the magnet.
The area surrounding a bar magnet where the magnet can exert a force is the magnetic field. This field extends from the North pole to the South pole.

Magnetic field lines are imaginary lines used to represent the magnetic field. These lines originate from the North pole and merge at the South pole.
The field lines are closer together near the poles where the magnetism is the strongest and spread out as they move away from the magnet.
A key property of magnetic field lines is that they never intersect or cross each other.
The direction of field lines is determined from the North pole towards the South pole when outside the magnet, and from South to North while inside the magnet.
The pattern of the magnetic field due to a bar magnet can be made visible using iron filings. The filings align along the field lines when a bar magnet is brought near them.

Every magnet, regardless of its size, has a North and a South pole.
Opposite poles (North-South) of two magnets attract each other, whereas the like poles (North-North or South-South) repel each other.
Cutting a bar magnet in half results in two smaller bar magnets, each having its own North and South pole.

A bar magnet can magnetise another magnetic material via induced magnetisation, when brought close together, the material aligns its domains in the direction of the field lines, effectively becoming a magnet.
Reversing these domains, via processes like heating or hitting, can result in the demagnetisation of the material.