1. DISCOVERY
The natural magnet was discovered by a shepherd boy. Actually, that natural magnet was an ore of iron which got stuck to the axe of the shepherd boy. That ore of iron is called magnetite or lodestone.
2. WHAT IS MAGNET?
A magnet is a piece of iron or any other magnetic object which gets attract to another magnetic object.
3. WHAT ARE THE IMPORTANT PROPERTIES OF MAGNET?
There are two important properties of magnet. They are:
a. ATTRACTIVE PROPERTY- The magnet attracts small pieces of iron towards itself. This property is known as attractive property.
b. DIRECTIVE PROPERTY- If a magnet is suspended freely, then the magnet will always point at geographic north-south direction. This property is called directive property.
The other important property of a magnet are as follows:
a. A magnet has two poles- North pole and South pole.
b. The space around a magnet is known as magnetic field.
c. The direction of magnetic field is found as a direction along which the north pole of a magnetic compass would move.
d. The strength of a magnet is commonly explained by the magnetic field lines.
e. The field lines run from South pole to North pole inside a magnet.
f. The field lines tends to contract longitudinally. That is, the field lines bend along the length and are space loosely near the middle of a magnet. For this reason the middle of a magnet have minimum strength.
4.WHAT IS ATTRACTION AND REPULSION OF A MAGNET?
a. ATTRACTION- When two magnets get attracted by each other, then this is called attraction of a magnet. Always north pole and South pole attracts each other.
b. REPULSION- when two magnets repel each other, then this is called repulsion. Always same direction that is North pole-North pole and South pole-South pole repel each other.
5. WHY REPULSION IS THE SUREST TEST OF MAGNETISM?
A magnet can attract another magnet or a magnetic substance. So, by attraction we can't find whether a substance is magnet or magnetic substance. But a magnet can repels only another magnet. So, repulsion is a surest test of magnetism.
6. STATE SOME BASIC LAWS OF MAGNETISM.
There are some laws of magnetism. They are as follows:
a. A magnet can attract only a magnetic object such as iron, steel, cobalt, nickel etc.
b. When a magnet is suspended freely it always points in north-south direction.
c. Opposite poles of a magnet attract each other and similar poles of a magnet repel each other.
d. Repulsion is the surest test of magnetism.
e. The strength of a magnet is more near its end poles.
7. HOW CAN I MAKE MY OWN MAGNET?
There are several methods for making a magnet such a 'single touch method', 'double touch method' etc. However, the most easiest method is is the single touch method. It is described under:
Step 1- take a rectangular flat piece of iron AB and place it on a flat table.
Step 2- At the end a place the north pole of a permanent bar magnet.
Step 3- Rub the magnet over iron from A to B, without lifting it.
Step 4- at the end belief the magnet and again place it at the end a and repeat it 20 to 30 times.
Step 5- Now remove the permanent bar magnet. And test the end A of the bar magnet by bringing it near the north pole of freely suspended magnetic needle.
You will notice that north pole of magnetic needle gets repelled. This proves that the flat piece of iron has been magnetized. Similarly, you can magnetise an iron pin, a steel blade, a steel scale, a sewing needle etc.
8. PRECAUTIONS WHILE USING A MAGNET.
1. If you have made or rough handled or heat a magnet then it will lose its magnetism.
2. Don't place it near any electronic gadgets with very sensitive and powerful magnet. Like computers, televisions, music systems etc. So be careful. If you place then the magnets will be demagnetized.
3. It has been found that magnets lose their magnetism, if kept without any protection. Keep the bar magnets in pairs in a wooden box, separated by a piece of wood such that the opposite in face each other. In case of a horseshoe magnet a piece of soft iron should be placed at its end.
No comments:
Post a Comment