Magnetic force

Magnets “stick” to some metals. Iron, nickel, and alloys containing either or both of these elements, are known as ferromagnetic materials. When a magnet is brought near a piece of ferromagnetic material, the atoms in the material become lined up, so that the metal is temporarily magnetized. This produces a magnetic force between the atoms of the ferromagnetic substance and those in the magnet.
If a magnet is brought near another magnet, the force is even stronger. Not only is it more powerful, but it can be repulsive or attractive, depending on the way the magnets are turned. The force gets stronger as the magnets are brought near each other.
Some magnets are so strong that no human being can ever pull them apart if they get “stuck” together, and no person can bring them all the way together against their mutual repulsive force. This is especially true of electromagnets, discussed later in this chapter. The tremendous forces available are of use in industry. A huge electromagnet can be used to carry heavy pieces of scrap iron from place to place. Other electromagnets can provide sufficient repulsion to suspend one object above another. This is called magnetic levitation and is the basis for some low-friction, high-speed trains now being developed.