A bar magnet is a rectangular object that has a magnetic field. It is usually made of iron or steel, but it can also be made of any ferromagnetic substance or a ferromagnetic composite. A bar magnet is almost always a permanent magnet, meaning that it will retain its magnetic field for a significant period of time without the use of a supplied electric current.
Each end of a bar magnet is considered a pole – one being north, the other south. When freely suspended, a bar magnet will align itself so that the end of its northern pole points towards the Earth’s magnetic North Pole. This works in the exact same manner as a compass needle, which itself uses or is a magnet. If a bar magnet has one end painted red, that end is traditionally the bar magnet’s north pole.
Bar magnets are usually made of ferromagnetic materials. Ferromagnetic materials are elements that can naturally have a magnetic field. They include cobalt, iron, and nickel. Some magnets are made of composite materials which combine ferromagnetic materials with other substances such as aluminum, clay, or resin.
A bar magnet, like other magnets, has uses based on its magnetic attraction. This magnetic attraction draws other ferromagnetic materials to it or the bar magnet towards them. These uses include: picking up small ferromagnetic items such as screws and metal shavings; being used as “magnetic stirring rods” on laboratory hotplates; and holding papers and other items to the sides of refrigerators.