Electromagnetism

18May08

Electromagnetism. I’ve heard the term a thousand times before now but never really grasped the concept until quite recently. Sure, I know what electricity is and I know all about magnets, but what’s electromagnetism all about and why is it so important?

Let’s nutshell it to begin with and go from there. Electromagnetism is the concept that a moving electric current creates a magnetic field and a moving magnet creates an electric current. As an example, electricity moving through a wire creates a magnetic field around itself while a magnet moved past a wire or through a coil of wire creates an electric current in that wire or coil.

Electric motors and generators work on these two ideas. In an electric motor an electric current moves past magnets that then turn a drive shaft. A generator with a chemical source of energy moves magnets past a coil of wire and creates an electric current.

Electromagnetic waves are self propagating. An electric wave sets off and the movement generates a magnetic wave that moves along with the electric wave. In turn, as this magnetic waves moves it creates an electric wave. The electric wave moving with the magnetic wave creates another magnetic wave, and so on.

Light, radio, x-rays etc are all electromagnetic waves with the variation in their wavelength determining their properties. It’s important to understand that all electromagnetic waves move at the speed of light (which is roughly 3×108 m/s).

There is so very much more to this subject but to go further is to branch out into other subjects and delve into more difficult territory.

As a final word I just wanted to mention that this article describes the classical model with an electromagnetic field regarded as a smooth, continuous wave. In the quantum world an electromagnetic field is regarded as a collection of particles, or photons. I’ll leave quantum physics until another day as I’ve only recently begun to understand how it works. Anything I say now is likely to be wrong.

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