Observations on Static Electricity
You asked about static electricity ... probably because you have seen or experienced it many times. Every bolt of lightning you have observed is a massive static electric discharge between storm clouds and the Earth. Whenever you have rubbed a balloon against your clothes and then had it stick to the wall or felt it lift the ends of your hair ... that's static electricity too. If you ever walked across a carpet and then had a spark jump from your finger to a light switch ... static electricity. In fact the little spark that nips the end of your finger is the same thing as lightning, just very, very much smaller. The "crash" of thunder you hear after a lightening strike is caused by the same phenomenon as the tiny "snap" you hear at the end of your finger.
A flash picture I took tonight of our group sitting outside in the pitch dark watching a major thunder & lightning storm out over Penobscot Bay.
All matter is composed of different types of atoms and all atoms are built of protons (which carry a positive charge) and electrons (which carry a negative charge). Some materials are composed of tough atoms that hold together tightly and generally the number of protons and electrons are well balanced. These atoms as a whole have a neutral charge ... neither negative or positive. However, some materials have atoms that can easily loose a few of their electrons in collisions or friction with other atoms. When they loose some of their electrons, their overall charge goes positive. The lost electrons attach to something else, temporarily giving it a negative charge. Nature wants to restore the natural balance and the electrical charges in these materials usually settle back to their neutral state after a short while. The charge moves peacefully from one atom to another until all is neutral again.
However, if there is a lot of friction (rubbing a balloon vigorously on your sweater) or a great many collisions (air masses whipped together in a storm cloud) the unbalanced charges can accumulate faster than they can settle back down. Then things get interesting. Parts of the system get more and more positive and other parts more and more negative. Eventually, there is just too great a discrepancy in charge for the insulating properties of the air to hold back and electricity jumps from one place to another as a "spark" with all the accumulated charge moving at once.
This can be amusing when it is a small snapping spark at the end of your finger after you have walked across a rug or it can be a dangerous discharge of millions of volts from a big storm cloud to a tree, leaving the tree a smoking ruin. The extremely high heat of lighting heats the air (and the poor tree) so fast that an explosive sound is made. That's thunder.
Lots of things can increase or decrease the effects of static electricity. For example, if you walk across a wool rug in rubber shoes shuffling your feet, you will cause a great deal of friction and dislodge a lot of electrons. So you (your whole body) builds up a charge. If the air is very dry (say indoors in winter), the air will be a very good insulator and won't help you by taking away some of that charge. It will build up more and more. When you reach that light switch, you are in for a little shock as the charge finally finds a pathway through the wall back to the rug.
If your rug is nylon or your shoes are plastic, fewer electrons will stick to you as you walk. If the air is humid, the electrons can jump to the water vapor molecules in the air all around you as fast as they are accumulated. You won't get a shock.
Another trick to try under great sparking conditions (a dry day with a wool rug and rubber shoes, etc.) is to walk around holding a sharp pin in your hand. The extra electrons accumulating in you body want to spread out evenly all over you (electrons repel other electrons). However, at the end of that pin, there isn't enough space for them to spread out so they are concentrated and they can get so excited that they spark a bit even before you get to the light switch. You can actually hear a hiss as they jump off into the air trying to get away from each other. If you turn off the lights, you can actually see a faint blue spark at the end of the pin. I used to demonstrate this with your father at our home in Connecticut.
That trick is the reason that lightening rods are very sharp metal rods sticking way up into the air at the tops of buildings. Most folks think their purpose is to carry the lightening down to the ground if there is a strike. Instead, they allow the excess charge in the building to "hiss away" into the air harmlessly. This reduces the probability that the building will be struck.
Well, that's some of what I know about static electricity.
