Expert: Ralph Salier-Hellendag - 2/19/2005

Question
Mr. Hellendag,
   Hi...I am a student at Christopher Newport University. In my natural science class we have to do a 1 minute script/video project on a science concept of our choice and consult with a science expert on the information we are using in the video. My group chose to do our video on static electricity. If you can make sure all of these facts we are going to use in our video are correct I would really apperciate it. Thanks:)

-Static electricity is an electric charge built up on persons or objects through friction.
-Static electricity is electricity is electricity that does not flow in a current. It is generated by rubbing two nonmagnetic objects together.
-Usually substances that don't conduct current electricity (insulators) are good at holding static electricity.
-The electrons that are transferred in static electricity are stored on the surface of an object.

Answer
Sarah

So you live in Newport News VA!  I used to live there in the 1990's. I worked for Siemens Automotive on Bland Blvd.  

As for your questions:

1) this is correct, Static electricity is an electrical charge which can build up on a person, object and generally in the atmosphere (as in lightening).  And yes it is generally caused by friction between dissimilar materials.

2) Static electricity does flow in an unconventional current or discharge cycle.  That is what lightening is, the " nutralization" of the charge, or closing of the charging circuit.  It can be directed through a circuit thus it can flow as a current.  That is  why when lightening hits your house it can knock out the power but blowing the circuit breakers.  See #1 above about the friction between dissimilar materials.  I have never tested two magnetic materials to build up a static charge but a Van de Graff machine stores the charge in a large steel ball and it is built up in the steel ball by friction of a strap running over a bar of dissimilar material that is touching the steel ball.  Steel is a magentic material.

3) Laytex, or natural rubber is very good for building up a charge through friction as is nylon and other plastic materials.  These are insulators which do allow for a charge to build up on the surface.  However, this charge seeks to discharge as quickly as possible which is why when you touch metal after walking over the carpet, you can get a shock.  But many substances both insulating and non-insulating can build up a static charge.

4) It depends on the nature of the material where the charge is held.  On non-insulators it may work like a capacitor or battery where the charge is internalized while with most insulators, the charge is carried on the outside.  In both cases, the electrons are held at the molecular level and they are "free" agents with the ability to discharge or neutralize the charge by "going to ground".  

I hope that I have not confused you with these explanations but it is not a simple subject.  There are a lot of variables.  Including humidity, ambiant electrical activity (like near power lines or during a thunder storm) and the materials in use.  There are some good resources at William and Mary as well as the local public library.. Try to isolate the variables and use the Van de Graff materials as an example.