How to Colonize an Asteroid
Understanding a
Flashlight
Let's start with
a really simple electronic device with which we are all familiar and see
how it works, the humble flashlight. How does a flashlight produce light?
Well, let's see, what is inside a flashlight? There are batteries inside,
which are a source of electricity, or the "potential" to make electrons flow.
There is also a switch, a metal strap or wire from the far end of the batteries,
and a light bulb mounted in a reflector.
When you turn the switch on, chemical reactions in the battery begin to occur, which cause electrons to move through the circuit. If you open the switch, or the filament of the light bulb breaks, the chemical reactions in the battery cease, because there is no path (or "circuit") for the electrons to flow (this is know as an "open circuit"). The filament of the bulb is made from a material which resists the flow of electricity. This resistance causes the wire in the filament to heat up to the point where it gives off light.
© 1998, Robert Lyon Richards