Magnetism Simulations

Magnetism is the branch of physics concerned with magnetic fields and the forces they exert. A magnetic field surrounds permanent magnets and any moving electric charge, and although it cannot be seen directly, it can be mapped by the direction it would push a small test compass. Simulations are particularly helpful here because they can draw these field lines explicitly, showing how a field emerges from one pole of a magnet and curves around to the other, and how the fields of separate magnets combine or oppose.

Magnetism and electricity are two aspects of a single underlying interaction. An electric current always produces a magnetic field around it, which is the working principle of the electromagnet: a coil of wire that becomes magnetic when current passes through it and loses its magnetism when the current stops. This effect can be strengthened by winding many turns or adding an iron core, and it allows magnetism to be switched on and off and controlled, unlike that of a permanent magnet.

The reverse effect is equally important. According to Faraday's law of induction, a changing magnetic field through a coil induces a voltage across it, so moving a magnet near a coil drives an electric current. Animated models can show a magnet being pushed through a coil and the resulting current appearing, making this otherwise abstract relationship concrete. Together, the production of magnetism by currents and the generation of currents by changing fields explain the operation of motors, generators, and electromagnetic devices.

Frequently asked questions

What produces a magnetic field?

Permanent magnets produce one, and so does any moving electric charge or electric current. This link between current and magnetism is fundamental to electromagnetism.

How can magnetism be switched on and off?

An electromagnet is magnetic only while current flows through its coil, so cutting the current removes the magnetism, unlike a permanent magnet.

How does moving a magnet near a coil create a current?

Faraday's law states that a changing magnetic field through the coil induces a voltage, which drives a current. This is the basis of the electric generator.