Measuring Electrical Potential

[Zacharde]

I'm working on a project with some friends where we need to measure the potential electrical charge of various things. It is a fairly wide list, including hair, tapwater, the chair of the air around us, etc....

 

We want to know if the electrical potential is negative or positive, and ideally be able to measure magnitude.

 

This isn't something we typically do, and we can't afford to go to a lab. This is a hobby, and half the point is to learn as we go. So we are trying to research the correct instrumentation to obtain a measurement of the potential.

 

Obviously, a voltmeter isn't the tool for the job. From some preliminary research, it looks like we need a electrometer, but I'm finding it a little difficult to work out how to use one, and a little unsettled by how much they seem to cost.

 

The maker in me wants to build the instrument of course.....but I accept I may just need to find one we can use.

 

I'm looking for a little guidance, in the form of useful links, or a conversation with someone who can offer some expertise. How would you go about measuring the charge of air, or tapwater?

 

Thanks in advance for any assistance!

[EdEarl]

Zach, you can begin with an electroscope. The least expensive can be made with aluminum foil and a plastic bottle. They register electrons, which push the two Al leaves apart. The further the leaves are repelled, the more electrons and higher potential. A crude calibration can be done by knowing the volts needed to make a spark of specific distance in dry air. See references below for more info.

 

http://en.wikipedia.org/wiki/Electrometer#Gold-leaf_electroscopes

http://amasci.com/emotor/voltmeas.html