What Materials are magnetic
Materials that are attracted by magnets are called magnetic or ferromagnetic materials.
E.g. cobalt, nickel and steel.
Materials that are not attracted by magnets are called non-magnetic materials.
E.g. brass, copper, wood and plastics.
A material that retains its magnetism for a long time is called a permanent magnet.
They are usually made of steel and alloys like alnico and alcomax.
Another type of permanent magnet is made from ferrites.
Its a common misconception that all metallic materials are magnetic. This is not the case. Although almost all metals conduct electricity, not all metals are magnetic. E.g. brass and copper. However these materials can sometime produce(with the help of current) magnetic fields. We will explore this in later chapters.
Magnetic poles
The two ends of a bar magnet where the magnetic effects are the strongest, are called the poles of the magnets.
The end of a freely suspended bar magnet that points to the northern end of the Earth is called the north-seeking pole (i.e. north pole or N pole). The other end of the magnet that points to the southern end of the Earth is called the south-seeking pole (i.e. south pole or S pole).
Law of Magnetic Poles
Like poles repel, unlike poles attract.
Identifying a magnetWe cannot assume an object is a magnet simply because it attracts a bar magnet. However if repulsion occurs between an object and a known magnet, then we can conclude that the object is indeed a magnet.
Hence, repulsion is the only test to confirm that an object is a magnet.