LECTURE                              STATIC ELECTRICITY

In this lecture you will learn:

"Static electricity is the accumulation of electrical charges on the surface of a material, usually an insulator or non-conductor of electricity. It is called “static” because there is no current flowing, as there is in alternating current (AC) or direct current (DC) electricity.

Typically, two materials are involved in static electricity, with one having an excess of electrons or negative  charges on its surface and the other material having an excess of positive (+) electrical charges. Atoms near the surface of a material that have lost one or more electrons will have a positive (+) electrical charge. 

If one of the materials is an electrical conductor that is grounded, its charges will drain off immediately, leaving the other material still charged.

Cause of static electricity

Static electricity is usually caused when certain materials are rubbed against each other—like wool on plastic or the soles of your shoes on the carpet. It is also caused when materials are pressed against each other and pulled apart.

The process causes electrons to be pulled from the surface of one material and relocated on the surface of the other material. It is called the triboelectric effect or triboelectric charging.

The material that loses electrons ends up with an excess of positive (+) charges. The material that gains electrons ends up an excess of negative (?) charges on its surface." 
citation: http://www.school-for-champions.com/science/static.htm

Negative (-) charges 
collect on PCV pipe 
You may have noticed that when you wear certain clothing like nylon jump suits and slide over the car seat, you tend to zap on the door handle as you get out of the car. This seems to happen mostly in winter
- the protons of the nucleus are responsible for the + charges

- the electrons of the shell are responsible for the - charges

- electrons are the only particles that move or are transferred

- touching something allows electrons to "leak" off

- positive charges repel
- negative charges repel
- positive is attractive to negative
- this attraction is affected by amount of charge AND BY DISTANCE

   1. Turn on the faucet so that the water runs out in a small, steady stream, about 1/8 inch thick.
   2. Charge the comb by running it through long, dry hair several times or rub it vigorously on a sweater.
   3. Slowly bring the comb near the water and watch the water "bend" toward the comb. 
   4. This project can also be done with a balloon.

FABULOUS JAVA OF HOW THIS HAPPENS!!! http://micro.magnet.fsu.edu/electromag/java/lightning/

- Lightening is an example of what happens when static electricity builds up on a GIANT scale.
– A charge differential builds up in storm clouds
- The result is negative and positive charges are separated
- On the ground, charges accumulate on wood (trees) and other non-conducting materials
- When the charge differential is large enough, it becomes unstable, and a small discharge called a step-leader occurs. This sets up a path through the air that otherwise is very resistant to electron movement. Once the step leader sets up the path, the full electrical discharge occurs.

- the tree builds up static charges.
- It is also the highest item on most golf courses.
- when a tree is hit, the discharge occurs in a wide circle around the tree. If the ground is hit, the discharge travels
- In addition, holding an object composed of conducting metal ribs, like an umbrella, becomes a secondary discharge point.
-  wet ground makes a good conductor.
-- so contact between the person and the wet ground, like with a metal golf club and metal spikes in the shoes increases the likely hood of being a conductor

Electrons move freely thru metals which don't hold onto their electrons tightly.  Electrons move through metals like water thru a sieve, so metals actually don't accumulate static electricity for this reason.


Electrons are tightly attached in non-metals and charges accumulate on surface and show static electricity. Glass and plastics (organics in general ) are good non-conductors.