Why does a freely suspended magnetic needlepoint in geographic north-south direction? Name a device which is based on the above phenomenon.

Hint:A magnet aligns itself according to the earth’s magnetic field and the magnet has two poles. Almost every planet has a North pole and South pole.

Complete step by step solution:
Earth has two geographic poles, the North Pole and the South Pole. They are the places on earth’s surface that earth’s imaginary spin axis passes through. Our planet also has two magnetic poles, the north magnetic pole and south magnetic pole just like a bar magnet. The magnetic poles are nearer but not quite in the same places as the geographic poles. The needle in a compass points towards a magnetic pole. Earth’s north magnetic pole is actually the South Pole of earth’s geographic poles and vice – versa.

Hence, a freely suspended magnetic needlepoint in a geographic north-south direction. The magnetic compass is the device that uses this principle.

Addition information: Every magnet is made up of tiny magnets called domains. These domains when aligning in a particular manner result in a net magnetic field which is attracted or repelled by an external magnetic field. Magnetic substances are of a ferrimagnetic, ferromagnetic or antiferromagnetic type. The magnets lose their properties on heating or by applying pressure.

Note: Earth’s North pole is actually the South pole of Earth’s geographic poles and vice-versa. The magnetic field of the earth is created due to its rotation along the axis. The other factors which are responsible for a magnetic property are friction between the earth surface and the atmosphere.