Magnetic and Non-Magnetic Materials
We know that a magnet pulls some objects. Does a magnet pull objects made up of all kinds of materials? Let us perform an activity to distinguish the objects which are either pulled by the magnet or not. Those materials which are attracted by the magnet are called magnetic materials. The other materials are non-magnetic materials. The iron, nickel and cobalt are magnetic materials. Copper, plastic and rubber are nonmagnetic materials. Over 2000 years ago, the Greeks found Loadstones. The Chinese found that a dish carrying a piece of loadstone would float in water such that the loadstone always settled in a North South direction.
Properties of a Magnet
A magnet has some more properties other than attracting iron objects. Let us perform an activity to explore its properties.
Poles of a Magnet
The end of the bar magnet that is pointing towards the geographic north of the Earth is called North Pole of the bar magnet, while the other end that is pointing towards the geographic south is called South Pole of the bar magnet. The North Pole is usually painted red while the South Pole is painted blue. The symbols N and S are engraved at the poles (Figure 9.3). It is interesting to find where the magnetic force in a magnet is strongest. Let us perform an activity to demonstrate this property of a magnet. Like poles repel each other and unlike poles attract each other.