How to make a temporary magnet?
Using magnetisation, we can make temporary magnets. Let us look at two ways of doing it.
● Iron nail as a temporary magnet
Any ferromagnetic material like an iron nail, vertically hung from one of the poles of a magnet acts as a temporary magnet. It retains its magnetism as long as it is in the external magnetic field of the magnet. This can be verified by bringing any lightweight ferromagnetic object in front of it. It will get attracted by the first nail.
● Iron bar as a temporary magnet
Rubbing a magnet 30 to 40 times on a horizontal line along the length of a non- magnetised iron bar can magnetise it. It is important to rub in one direction.
When an iron nail or any other ferromagnetic object is brought near the bar, the bar will attract it. The more you rub it, the longer it will retain its magnetism.
What is Demagnetisation?
It is the opposite of magnetisation. Demagnetisation is a process in which the magnetic material is demagnetised.
In the above examples, if the iron nail and iron bar are taken away from the magnets, they lose their magnetism. That is, they become demagnetised
What are the materials used in permanent magnets?
The two most common types of permanent magnets are:
- Magnets made of ALNICO, which is a compound made up of aluminium, nickel and cobalt. Most commonly used permanent magnets are made of this compound
- Neodymium magnets which are made up of an alloy of neodymium, iron and boron. These are the strongest permanent