Static electricity results from electrons being knocked off of the surface of atoms, which leaves a net positive charge. Learn about conductors and insulators in static electricity with help from a science teacher in this free video on physical science.
Hi. I'm Steve Jones. And I'm going to explain what causes static electricity. Now, first of all, there are two main types of material. There are conductors and there are insulators. Okay, there are things in between, too. And some things are better conductors and some things are worse conductors. But the thing that distinguishes the two is that a conductor contains free electrons. That is, within the atom, the electrons within the atom are able, actually, to move through the material. And when we apply a field across the material, the electrons will flow. So we get an electron movement. Now, in the case of an insulator, this does not happen. In the case of an insulator, if we put an electric field across the insulator, the electrons are bound to the atom. So they'll be pulled a little bit this way, but they can't move through the material. That's why an insulator. So the electrons don't move through it, it doesn't conduct electricity. So what causes static electricity? Well the answer is fairly simple. You can physically knock electrons off the atoms at the surface. So here's a surface atom, and literally, by rubbing it. I take my piece of plastic for example, which is an insulator. So this would be plastic. And i rub the surface with a cloth. Then what will happen is as I rub it, I will knock electrons off. So the electrons will fly off into the atmosphere, and that will leave a net positive charge on the surface of the plastic. That is static electricity. And you'll have noticed, for example, when you take off a nylon shirt or nylon blouse at night, very often you get little sparks. And this is because of these electrons being pulled off or electrons being pushed on. They are actually statically charging. And it has to be an insulating material, like plastics. And most modern materials are made out of plastics. So this is how we create our static electric charge. And the static electric charge will stay until we actually allow electrons to neutralize those. So obviously, sooner or later, electrons in the air will find these positive-charged places and will fill them up, and it will lose its charge. Eventually, it'll lose its charge. So that, basically, is what causes static electricity.