Chapter 4 — Exploring Magnets

Chapter 4 'Exploring Magnets' covers magnets and their properties: magnetic and non-magnetic materials, the two poles of a magnet (North and South), why a freely suspended magnet always points north-south, how unlike poles attract and like poles repel, and how the magnetic compass works for finding directions.

Lodestones are naturally occurring magnets discovered in ancient times. The magnets used by sailors in the olden days were based on lodestones. Later, people found that magnets could also be made from pieces of iron, and today magnets are made from different materials.

Magnetic materials are attracted towards a magnet — examples are iron, nickel, and cobalt. Non-magnetic materials are not attracted towards a magnet — examples are wood, rubber, plastic, and glass.

Every magnet has exactly two poles — the North pole and the South pole. If a magnet is broken into smaller pieces, North and South poles always exist in pairs even in the smallest piece. A single North pole or South pole cannot exist — they cannot be separated.

A freely suspended magnet always comes to rest along the north-south direction because Earth itself behaves like a giant magnet. The end of the magnet that points towards geographic North is called the North pole (or North-seeking pole) of the magnet.

Like poles (North-North or South-South) of two magnets repel each other. Unlike poles (North-South) attract each other. This is the fundamental rule of magnetic interaction between two magnets.

A magnetic compass is a small circular box with a transparent cover containing a magnetised needle on a pin, free to rotate. The needle rests in the north-south direction. To use it, place it on a surface, let the needle rest, then rotate the compass box until N and S on the dial align with the needle — all directions are then shown on the dial.

Repulsion is the key test. A plain iron bar is attracted by both poles of a magnet. Only a magnet can repel the like pole of another magnet. Alternatively, a freely suspended magnet always rests in the north-south direction, while a plain iron bar can rest in any direction.

Yes. The magnetic effect can act through non-magnetic materials. Placing wood, cardboard, plastic, or glass between a bar magnet and a compass needle causes no appreciable change in the deflection of the compass needle.

The matsya-yantra (also called machchh-yantra) was an ancient Indian navigation device. It consisted of a magnetised fish-shaped iron piece kept in a vessel of oil. It was used by Indian sailors for navigation at sea, much before the modern magnetic compass became widespread.

Stroke an iron sewing needle with one pole of a bar magnet in the same direction at least 30 to 40 times. Pass the magnetised needle through a cork and float the cork in a glass bowl filled with water. The needle will rotate and come to rest pointing north-south — your homemade compass is ready.

Yes, the NCERT Class 6 Science (Curiosity) Chapter 4 PDF is available for free. No sign-up or account is required to download it from this website.