Chapter Notes and Summary
• Magnet has property to attract objects made of iron.
• substance that can attract iron, cobalt, or nickel is known as magnet.
• Magnet was discovered by a shepherd named Magnes around 2000 BC., who lived in Magnesia, Greece.
• Materials that get attracted towards magnets are magnetic materials.
• Materials that does not get attracted towards magnets are non-magnetic materials.
• Pin-holders, screwdrivers, refrigerator stickers, junkyard cranes, etc., consist of magnets.
• There are two poles of a magnet–North Pole (N) and South Pole (S).
• A large number of iron filing sticks at two poles of magnet in comparison to rest of magnet body.
• A freely suspended bar magnet always aligns along North-South direction.
• direction at a place can be identified with help of a bar magnet or a magnetic compass.
• A magnetic compass consists of a magnetic needle that always comes to rest in North-South direction.
• In olden days, sailors found direction by suspending bar magnets.
• Like poles always repel each other. Unlike poles always attract each other.
• An iron bar becomes a bar magnet when one of pole of a bar magnet is rubbed on it several times. This is known as touch-stroke method.
• A magnet loses its magnetic property when dropped from a height, hammered, or heated.
• Magnets can be stored safely by keeping them away from cassettes, CDs, mobile, TVs, plastic cards, etc.