How does a compass needle function?

A compass needle functions primarily because it is a magnet that aligns with the Earth's magnetic field. This alignment occurs due to the magnetic properties of the needle itself, which is typically made from a magnetized material. When the compass is held level, the needle rotates until its ends are oriented along the Earth's magnetic field lines; one end points towards the magnetic north and the other towards the magnetic south.

This principle is rooted in the concept that magnetic fields exert forces on magnetic materials, causing the compass needle to align with the external magnetic field it is in. The Earth's core generates a magnetic field due to the motion of molten iron and other metals, which creates a magnetic "north" and "south" pole. As a result, the compass needle's ability to indicate direction relies on this interaction with the Earth's magnetic field, making it a critical tool for navigation and orientation.