What is Magnet -
What is Molecular Theory of Magnetism -
We know that every substance consists of small particles called Molecules. The molecules of some substances behave like independent magnets. In normal state, these molecules are scattered randomly in the material and they neutralize each other's effects.Consequently, in normal state matter does not have magnetism. When the external magnetic field acts on the substance, its molecules begin to settle in the direction of the magnetic field.
When all the molecules are arranged in the direction of the magnetic field, the material becomes a magnet. The magnetic properties present in the molecules arise due to the orbital and spin motion of the electrons present in their atoms. This is called the unique principle of magnet.
What is Properties of Magnet -
The following properties are found in a magnet.1. It attracts iron filings. The two parts of the magnet where most of the iron powder sticks are called Pole.
2. The freely hung magnet stops in the north-south direction. The north tip of the magnet is called the north pole and the south tip is called the south pole. Due to this magnetic property of magnet, it is also called load stone.
3. With two magnets, there is repulsion in the homogeneous pole and attraction in the heterogeneous pole.
4. If a magnet is repeatedly rubbed on an iron rod, it also becomes a magnet.
5. A magnet is red-heated and beat or banged to cool it down and its magnetism gets eroded or dissipated.
How Many Types of Magnets-
The magnets can be placed in the following two main categories.1. Natural magnet
2 . Artificial magnet
1- Natural magnet- Magnetite stone found in nature is called natural magnet, its shape is unformed and its magnetic field intensity is also very low, they are no longer used.
2- Artificial magnet- Magnets made of iron magnetized metals and alloys of iron are called artificial magnets. There are two types of these.
1- Permanent- Permanent magnets are those whose magnetization lasts for many years. These are made of steel or alloy magnetized metals. The alloyed metal is made of aluminum, nickel, iron, copper and cobalt (mixed in the ratio of 8: 14: 51: 3: 24). It is called Alnico or Alconex. Magnets were made by friction, but now-a-days, steel or rod of alloyed metal is kept for some time between powerful current coils and it becomes a permanent magnet. Hunting or the size of tap horse.
2- Temporary- Electromagnets made of soft iron are called temporary magnets. They are made of many sizes as required. A temporary magnet exists as long as the current flows from its coil.
What is Magnetic keeper -
Generally permanent magnet rods are made in horseshoe and cylindrical shape. When the magnets are not being used or are to be stored, the pole opposite the two magnets is mixed with a soft iron piece. This piece of iron is called a magnet-keeper, the keeper is joined together with a magnet or two magnets. Constructs closed magnetic circuit. This circuit helps in maintaining the magnetic power. In addition, the keeper also prevents the depressions in their magnetic force by creating opposite polarity in the magnet / magnet from any other external source.What is Electromagnet -
Soft iron rod can be magnetized by flowing current in a coil or solenoid while the soft iron rod is placed between the coil and the current is DC A magnet made in this way is called an electromagnet.What Features Of Electromengnet-
1. Its magnetic power can be increased gradually by decreasing the current value.2. Its polarity can be changed (by changing the direction of current flow).
3. Its magnetic power can be thousands of times more than that of permanent magnets.
4. Only a variety of electromagnets can be used in many types of instruments and equipment such as magnetic lift or crane eye iron emitting medical device etc.
It is used in power cables, relays, motors, generators, valid measuring instruments etc.