Electromagnetism

Electromagnetism: electricity and magnets

Most people rarely think about electricity and magnets as being related, but in physics, they are understood as the same fundamental force.

The force

In the universe, there are four fundamental forces: gravity, which is the pull that bodies with mass exert on each other, the strong nuclear force and the weak nuclear force, which are involved in the nucleus of atoms, and the electromagnetic force.

In the history of science, the electromagnetic force was first understood in the 1800s. The main scientists whose work clarified the nature of the force were the English physicist Michael Faraday and the Scottish physicist James Clerk Maxwell.

The following two experiments demonstrate the link.

Magnetic material, such as black sand, in the vicinity of a conducting wire, will experience a force when an electric current flows through the wire, and will move. The electric current generates a magnetic field.

When a changing magnetic field is applied to a conductor, a current runs through it. A changing magnetic field generates an electric current.

Geology

The earth contains a molten outer core made of metals like nickel and iron, that flow around in convection currents. The movement of these magnetic elements creates a changing magnetic field around the earth.

The south magnetic pole is the north geographic pole and the north magnetic pole is the south geographic pole.

In the sun, hydrogen fusion reactions are occurring, releasing enormous amounts of energy as heat and light. Ionised, or electrically charged particles, are released as well. They stream out from the Sun into the solar system as “solar wind.” The solar wind is affected by the earth’s magnetic field. Because the magnetic field is strongest around the south and north geographic poles, we see the auroras, or southern and northern lights. The particles are experiencing significant effects of the electromagnetic force, like the materials in Faraday and Maxwell’s experiments.

Energy systems

Electromagnetism is the basis for our energy systems. 

Hydro-powered turbines and wind turbines use renewable energy in nature to drive a generator. Generators are magnets that rotate around a conductor. As the magnetic field rotates, an alternating electric current is induced in the conductor.

Electric motors apply the same principle in reverse. An alternating electric current will create a changing magnetic field around a magnet which makes the magnet move. The kinetic energy of the moving magnet is harnessed mechanically to drive things like wheels.