Production of Conduction

Finally, let's talk about a metal's amazing ability to conduct electricity. Do you know what metal the wires in your house are made of? Here's a hint - they're probably brown. That's right - copper! Copper isn't actually the best metallic conductor of electricity. Silver is, but it's too expensive to use for wiring.

You can easily compare the conducting ability of metal to that of some other common materials using a flashlight. The best kind for this experiment is a cylindrical flashlight with a removable cap on one end. When you take the cap off, you should see the end of one of the batteries. First, make sure that the flashlight turns on! Then remove the cap, and place a small piece of aluminum foil on top of the battery you can see. Replace the cap, and turn the flashlight on. Does it still work? Open it up again, take the foil out, and put a small piece of paper in. Close it up again. What happens now? Try other materials you have around the house, like a small coin, plastic wrap, waxed paper, or any other thin solid that fits.

What you found was that the flashlight would only light up when you put a piece of metal in. Other materials didn't work. That's because those other things are insulators, which don't let electricity flow.

So how are metals different from insulators? The answer has to do with their electrons (not so surprising, considering that we're talking about electrical conduction!). In insulators, the electrons are stuck between the atoms of the material, and can't move around easily. But in metals, the electrons are free to move around, traveling from the area around one atomic nucleus to another. They're said to be delocalized, and the metal nuclei are sometimes described as being in a "sea of electrons". Normally, they just mill around in an unorganized way. But when the metal is hooked up to a battery or other source of electrical power, suddenly the electrons all start moving in one direction, creating an electrical current. Here's an animation that illustrates this.