Bar magnets are narrow, rectangular pieces of ferromagnetic material or composite that generate a magnetic field. They are permanent magnets, meaning they do not require constant electric current in order to retain their magnetism, and they have a smooth and uniform cross section and surface. They are usually made from iron or steel, but they can also be made from any ferromagnetic substance or composite such as cobalt, nickel, aluminum or clay.
Bar magnets have a south and north pole on each end and are the most common type of magnet shape. The main function of bar magnets is to to pick up small metallic objects like metal shavings or nails and screws, as magnetic stirring rods in laboratory applications, and as magnets on refrigerators. Their most common application is the needle used in compasses.
The north pole of the bar magnet aligns with the actual north pole, letting travelers know in what direction they are headed. However, this is not the only application of bar magnets, which are utilized in a wide range of industries and applications including: residential, for applications such as holding up receipts and pictures onto refrigerators; research, in which they are used as stirring rods on laboratory hotplates; and the food industry, utilized in restaurants to hold the cutlery in an organized and safe location.
The magnetic lines of force of a bar magnet form closed, continuous lines on either side of the magnet. They never intersect, and flow from north to south in direction. Each end of the magnet is considered to be a pole, so when cut in half a bar magnet automatically forms into two separate magnets, each with their own poles and magnetic field.
The average magnetization magnitude of bar magnets is 100,000 A/m, but this varies based on what type of ferromagnetic material is chosen. In addition, the magnitude of the magnetism relates to how strong and far apart the two poles of the bar magnet are. When using any type of magnet, especially bar magnets that are often found in homes, it is important to keep them away from any sort of electronic device, including speakers, televisions and radios.
Irreversible damage can occur to the data storage if it comes in contact with a magnet, even if it has a weak magnetic force. While the most obvious function of a bar magnet is to attract iron or ferromagnetic materials, bar magnets also function to attract or repel other magnetic alloys. These magnetic alloys include nickel, cobalt, some rare Earth metals and their alloys, and some naturally occurring minerals such as lodestone.
Bar Magnets Informational Video