Properties of magnets

Since magnetism is related to the movements of electrons. It is not surprising that the basic ideas of magnetism is very similar to those of electrostatics.

  • All the magnets have two types of poles: north-seeking poles or north poles and south-seeking poles or south poles.
  • The magnetic strength is the strongest at the poles of the magnet.
  • When you freely suspend a bar magnet in a horizontal position, the magnetic field of the bar magnet will interact with the magnetic field of the Earth. This will cause the bar magnet to come to rest in a north-south direction, where the north pole of the magnet points to the north pole of the Earth.
  • Like poles repel and unlike poles attract. (just as like charges repel and unlike charges attract).
  • Magnets attract magnetic materials such as iron, steel, cobalt and nickel.
  • The stronger a magnet, the larger will be the attractive or repulsive force between other magnets.
  • The closer together the two magnets are, the greater is the magnetic force between them.

 

Note:

  • All magnets have a north and south poles – 2 poles. Cutting a bar magnet in half simply produces two smaller magnets, each with its own north and south poles. What if you cut the half-bar-magnet? You will just obtain two smaller magnets, each with its own north and south poles. There is currently no experimental nor theoretical evidence for the existence of a magnet containing only 1 pole (magnetic monopole). If a magnetic monopole is found, most of the Physics texts will have to be rewritten.
  • Only magnets can be made to repel each other. Otherwise, the magnets will attract all other magnetic materials.
  • The Earth has a giant magnet, its axis is oriented more or less in the direction of the Earth’s rotation. The North pole of the Earth is actually the south pole of the Earth’s magnet. (The magnetic poles actually does not align perfectly with the real north and south pole. There is a small deviation. But let’s not concern ourselves with this for now.)

 

Magnetic materials are matter that is attracted by magnets.

  • Magnetic materials can be made into magnets.

 

e.g. Iron, steel, nickel, cobalt and many alloys based on these metals.

 

Non-magnetic materials are matter that is not attracted by magnets.

  • Non-magnetic materials cannot be made into magnets.

 

e.g. Wood, glass, plastics and metals such as copper and brass.

 

Note: It would be good if you can remember the examples.

 

Next: Induced Magnetism & Electrical Method Of Magnetisation

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