The simplest compass is a magnetized metal needle mounted in such a way that it can spin freely. (You can make one yourself by magnetizing an ordinary needle, placing it carefully on a slice of cork, and letting the cork float in a tray of water.) Left to its own devices, the needle turns until one end points north and the other south. You can usually figure out which end is which from the position of the Sun in the sky, remembering that the Sun rises in the east and sets in the west. So if you're looking down on the floating needle at about noon, with the eye on the left and the point on the right, and the Sun in front of you, you know the point is indicating north.
Construction of magnetic compassA magnetic compass has a flat circular aluminium box , at the base of which are marked directions like north , south , east and west. A suspended magnetic needle is placed in the center which can rotate freely . The north pole is if different colour to identify the north pole.
The magnetic compass is the most familiar compass type. It functions as a pointer to "magnetic north", the local magnetic meridian, because the magnetized needle at its heart aligns itself with the horizontal component of the Earth's magnetic field.
Magnetism is one of the first bits of science we learn in school and just about the first thing we discover is that "like poles repel, unlike poles attract." In other words, if you hold two bar magnets so their north poles are almost touching, they'll push away from one another; if you turn one of the magnets around so one magnet's north pole is near the other magnet's south pole, the magnets will pull toward one another.
That's all there is to a compass: the red pointer in a compass (or the magnetized needle on your home-made compass) is a magnet and it's being attracted by Earth's own magnetism (sometimes called the geomagnetic field—"geo" simply means Earth). As English scientist William Gilbert explained about 400 years ago, Earth behaves like a giant bar magnet with one pole up in the Arctic (near the north pole) and another pole down in Antarctica (near the south pole). Now if the needle in your compass is pointing north, that means it's being attracted (pulled toward) something near Earth's north pole. Since unlike poles attract, the thing your compass is being attracted to must be a magnetic south pole. In other words, the thing we call Earth's magnetic north pole is actually the south pole of the magnet inside Earth. That's quite a confusing idea, but it'll make sense if you always remember that unlike poles attract.