®
ES-9080A
012-07227G
Basic Electrostatics System
5
day can cause charge to easily build up in any moving object, including people. Minimize
all movement when demonstrating on a very dry day.
• Practice - Nothing can ruin the instructive value of a demonstration more than failure due to
a demonstrator’s unfamiliarity with the equipment and procedure.
Before presenting a series of electrostatic demonstrations, the student (and of course, the
instructor) should be made aware of the following:
• The theory and use of the Faraday Ice Pail. (This is adequately covered in the “Equipment
Description” section and in Demonstration 1.)
• The possible distortion of charge density due to improper use of the proof plane. (See the
“Equipment Description” section.)
• Residual charge may build up in the plastic insulator between the handle and disk of the
proof plane and charge producers. Make sure to ground these parts before any experiment.
• The capacitance of the electrometer must be considered when calculating the magnitude of
a charge from the voltage reading of the electrometer. (See Demonstration 3 for the
procedure necessary to determine the electrometer’s capacitance.)
By following the above principles and by practicing, the demonstrator should have a high
degree of success with the demonstrations and find their educational effect of great value.
Equipment Description
Electrometer (ES-9078A)
The Model ES-9078A Electrometer is a voltmeter used for direct measurements of voltage
and indirect measurements of current and charge. Because of its high (“infinite”) impedance
of 10
14
it is especially suited for measuring charge in electrostatic experiments. It has a
sensitivity nearly one thousand times that of a standard gold-leaf electroscope, a center-zero
meter that directly indicates charge polarity, and a digits display. The electrometer measures
charges as low as 10
-11
coulombs.
The electrometer includes a signal input cable (shielded), a banana plug patch cord, a signal
output (interface) cable, and a grounding cable (for use with the ES-9079 Basic Variable
Capacitor).
