Science · Class 6 · Chapter 4

Exploring Magnets

• Magnetic materials — Attracted towards a magnet, e.g. iron, nickel, cobalt.
• Non-magnetic materials — Not attracted towards a magnet.
• Poles of a magnet — The two ends where attraction is strongest.
• North / South pole — The end pointing north / south when freely suspended.
• Magnetic compass — A device with a freely rotating needle, used to find directions.
• Attraction — Pulling force between unlike poles.
• Repulsion — Pushing-apart force between like poles.

Chapter 4 · Concept 1 of 10

Magnetic and Non-magnetic Materials

• Natural lodestones were used by ancient sailors; today's magnets are usually made of iron and its alloys.
• Magnetic materials — Materials attracted towards a magnet — iron, nickel, cobalt, and some of their alloys.
• Non-magnetic materials — Materials not attracted towards a magnet — wood, plastic, glass, rubber.

Chapter 4 · Concept 2 of 10

Shapes of Magnets

• Magnets also come as discs, cylinders, and spheres — the poles are always at the ends of strongest attraction.

Chapter 4 · Concept 3 of 10

Poles of a Magnet

• Iron filings sprinkled near a bar magnet stick mostly at its two ends — the poles.

Chapter 4 · Concept 4 of 10

A Magnet Always Has Two Poles

• Break a bar magnet into pieces, and every piece still has its own North and South pole.

Chapter 4 · Concept 5 of 10

Finding Directions

• A freely suspended bar magnet always comes to rest along the north-south direction.
• Not just any iron bar — An ordinary (non-magnetized) iron bar will not settle in the north-south direction when freely suspended — this is one way to test if something is really a magnet.

Chapter 4 · Concept 6 of 10

The Magnetic Compass

• A magnetic compass has a magnetized needle that rotates freely and always settles pointing north-south — used for navigation for centuries (e.g. the matsya-yantra of Indian sailors).

Chapter 4 · Concept 7 of 10

Attraction and Repulsion

• The rule — Unlike poles (North-South) attract each other. Like poles (North-North or South-South) repel each other.

Chapter 4 · Concept 8 of 10

Repulsion Is the Real Test

• Attraction alone isn't proof — A magnet also attracts plain iron. So if two objects attract each other, one of them might just be an iron bar, not a magnet at all.
• Repulsion never lies — Plain iron never repels a magnet. If two objects push each other away, both must be magnets — this makes repulsion the sure test.

Chapter 4 · Concept 9 of 10

Magnetism Passes Through Non-magnetic Materials

• A compass needle still deflects even with wood, cardboard, plastic, or glass placed between it and a magnet.

Chapter 4 · Concept 10 of 10

Storing and Handling Magnets

• Do — Store magnets in pairs with unlike poles together, a piece of wood in between, and soft iron pieces across the ends.
• Don't — Don't heat, drop, or hammer a magnet, and keep magnets away from mobile phones and remote controls.

Quick Recap

Check Your Understanding

1. 1Fill in the blanks: (i) Unlike poles of two magnets ___ each other, like poles ___ each other. (ii) Materials attracted towards a magnet are called ___. (iii) The needle of a magnetic compass rests along the ___ direction. (iv) A magnet always has ___ poles.
2. 2True or False? (i) A magnet can be broken into pieces to obtain a single pole. (ii) Similar poles of a magnet repel each other. (iii) Iron filings mostly stick in the middle of a bar magnet. (iv) A freely suspended bar magnet always aligns north-south.
3. 3Column I shows pole positions of two magnets placed near each other (N–N, N–S, S–N, S–S). Match each to Attraction or Repulsion.