We will discuss here about magnetization and demagnetization.
What is magnetization?
The method of developing the properties of a magnet in a magnetic substance is known as magnetization. A magnetic substance like a piece of iron can be magnetized by electric current or by touching with a magnet. We know about the method of preparing an electromagnet and now we will discuss about the method of preparing a magnet by direct contact.
Take an ordinary bar (AB) made of iron magnetic substance). Place it on a table and hold it firmly with left hand. Now take a strong magnet bar. Hold it with right hand in a fixed inclined position. Bring one pole of the bar magnet in contact with end A of the iron bar as shown in the figure. Now rub it down to end B of the bar along the surface. Repeat the process several times. After a few minutes the iron bar will turn into a magnet bar.
What is demagnetization?
The method of removing of the magnetic properties of a magnet is known as demagnetization. It can be done by the following methods:
1. Hitting a magnet heavily by hammer.
2. Heating a magnet at high temperature.
3. Placing two magnets with same poles facing each other.
The following uses of magnet are:
(i) Magnet is used to prepare mariner’s compass.
(ii) Electric bell and air pumps used in aquarium, are prepared with electromagnet.
(iii) Magnet is the main component of all types of speakers, telephone receivers, head phones etc.
(iv) Magnet is used to fix the door of a refrigerator.
(v) In factories heavy iron articles are lifted by very strong electromagnets
(vi) Specially designed electromagnets are used to remove iron fillings from the eyes.