Educator

Magnetism

• Every magnet comes with two poles. Just like electricity, like poles repel each other, while opposite poles attract.
• Like electricity, we can describe the space around a magnet with a magnetic field and visualize it through the use of magnetic field lines.
• Unlike electricity, it is not possible to separate these poles from each other. Magnets always come as a dipole: two poles together.
• Moving charge creates a magnetic field.
• On an atomic level, all atoms involve moving charge (the electrons). Thus, they have many small magnetic fields. Normally, the random distribution of these fields results in no net effect.
• However, in some materials (such as iron), it is possible for these magnetic fields to all align and create a temporary or permanent magnet.
• Since moving charge creates a magnetic field, we can run current through a wire to create a magnetic field in the space around it.
• Through some clever arrangement, we can run current through some loops of wire, create a magnetic field, and then have it interact with another magnetic field, causing those loops to spin. Spin them with enough force, and you've got an electric motor.
• The reverse also works: a changing magnetic field induces a current in a conductor. If you place a loop in a magnetic field and make it spin with enough force, you've got an electric generator.