David Bangaru

4   MAGNETISM Important points to remember : 4. M AGNETISM 1. Natural magnet : Some iron ores possess the property of magnetism in their natural state. A lodestone is a natural magnet. It was discovered about 800 to 600 BC by the people living in Magnesia in Asia Minor. The properties of the lodestone (magnetite) were studied since then. This study developed into the science of magnetism. 2. Magnetic materials : Materials which are attracted by a magnet are called magnetic materials. Iron, cobalt and nickel are magnetic materials. 3. Nonmagnetic materials : Materials which remain unaffected by a magnet are called nonmagnetic materials. Plastic, rubber, copper, etc. are nonmagnetic materials. 4. Characteristics of a magnet : (1) Directional : When a magnet is suspended freely, it comes to rest in the north-south direction. (2) Attraction : A magnet attracts magnetic materials. (3) Non-separation of poles : The two poles of a magnet cannot