What is Static Electricity?

Most people have experienced static electricity in one form or another. If you do not use a fabric softener in your laundry you have most likely experienced your clothing clinging to other pieces and the need of effort to pull them apart. How many times have you touched a metal door handle in winter only to get a small electrical shock? A familiar school demonstration of rubbing a balloon on someone's hair and watching it stand on end. The practical joker that shuffles across a carpet before shaking your hand. These are all examples of static electricity but the question is, what exactly is static electricity?

Understanding atom structure:

An atom itself has no positive or negative charge, it will have the same number of protons, positive charges and electrons, negative charges. If an atom loses one or more electrons it will have a positive charge. If it gains electrons it will have a negative charge. Atoms like to be balanced and in simple terms will attract to an opposite charge in order to balance themselves.

Basic definition of static electricity:

Static electricity is formed from a build up of electrical charges on a surface. It is termed static, non-moving, because there is no AC or DC current flowing. Two substances are involved in the production of static electricity. One with a surface that has a negative charge and one that has a surface with a positive charge. The build up of these charges on the two surfaces will cause the atoms to attract or repel each other.

Triboelectric effect - the cause:

When various materials are rubbed against each other electrons can be knocked from the surface of the atoms of one material and transferred to the surface of atoms on the other material. This will cause one surface to have a more positive charge and the other to have a more negative charge. When a balloon is rubbed against wool or other clothing the balloon will gain electrons from the wool and become negatively charged. The balloon can then be made to stick to a neutral, non-charged, surface because the negatively charged atoms in the balloon want to be balanced. This effect can be seen after rubbing your shoes on a carpet and then touching a metal door knob. If you have built up a large number of negative charges they will jump and cause the spark that is seen and felt when touching the neutral door knob.

Dry air, moisture and lightning:

Static electricity will build up most easily in a dry air environment. Water molecules in the air can prevent the build up of charges on surfaces. However, in conditions of extreme turbulence that occurs in major storms the reverse can occur. The massive bombardment of water molecules against each other causes them to gain or lose electrons and build static. When this static becomes great enough the negative charges will be attracted to the ground to balance themselves. This attraction is seen as lightning. While an occasional spark from a door knob may not seem significant there can be a great deal of power in static electrical build up.

References:

http://education.jlab.org/qa/pen_number.html

http://www.aboutnuclear.org/view.cgi?fC=The_Atom,Structure_of_the_Atom

http://www.school-for-champions.com/science/static.htm