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Static Electricity

Have you ever walked across a carpet and then gotten a slight shock as you reached out to turn on a light switch? Or heard and felt all the "crackles" as you removed a load of clothes from the dryer? Or gotten a similar effect when stroking a cat?

You probably already know that these phenomena are generally known as "static," but do you know how and why they happen?


What has happend in each case is that the friction of the physical action — walking over the carpet, stroking the cat, etc. — has caused loosely-held electrons to be transferred from one surface to the other. This results in a net negative charge on the surface that has gained electrons, and a net positive charge on the surface that has lost electrons. If there is no path for the electrons to take to restore the balance of electrical charges, these charges will remain where they are (although they will gradually leak off, as they cannot easily be held forever).

If the electrical charge continues building through ongoing friction or similar action, it will eventually reach the point where it cannot be contained, and will discharge itself over any available path. Lightning is a spectacular display of electrical energies discharging themselves after being built to high values by clouds rubbing and bumping against each other. It makes no difference that clouds consist of many tiny droplets of water floating in the air; each such droplet contributes a small amount to the total charge, which can reach enormous totals.


The point about static electricity is that it is indeed static, which means that it doesn't move from one place to another. Therefore, while some interesting experiments can be performed with it, it does not serve the purpose of providing energy to do sustained work in any practical capacity. Static electricity certainly exists, and under certain circumstances we must allow for it and account for its possible presence, but it will not be the main theme of these pages.


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