Basic Electrostatics System
ES-9080B
8
®
• Avoid touching the neck during normal use. The oils from your hands will provide a path
for charges to leak off. If you experience a lot of leakage, wash the white non-conductive
neck with soap and water, rinsing generously; the leakage should disappear. Occasionally
clean the disk surfaces with alcohol.
• When you first use the charge producers, or just after cleaning, they may not produce
charges readily. Rub the white surface vigorously on the conductive proof plane disk.
• The charge producers are designed to be used with the ES-9078 Electrometer. They do not
produce sufficient charge for use with a standard electroscope.
The Proof Plane
As shown in Figure 5, the proof plane is an
aluminum-covered conductive disk attached to an
insulated handle. The conductive disk material is
carbon-filled black polycarbonate (about 10
3
) with
an aluminum surface. The nonconductive neck is
white polycarbonate (about 10
14
).
The proof plane can be used to sample the charge
density on charged conductive surfaces. A Faraday
Ice Pail and Electrometer can then be used to
measure the charge density on the proof plane (see
Figure 6).
By touching the proof plane to a surface, the proof
plane will acquire the same charge distribution as
the section of the surface it touched. By measuring
the charge on the proof plane, the charge density
on that part of the surface can be determined. The
greater the charge on the proof plane, the greater
the charge density on the surface where the proof
plane made contact.
When a proof plane is touched to a conductive
surface, the proof plane becomes part of the
conductive surface. If the effect on the shape of the
surface is significant, the sampling of the charge
density will not be accurate. Therefore, always
touch the proof plane to the conductor in such a way as to minimize the distortion of the
shape of the surface.
Figure 5: Proof Plane
-
Handle
Non-conductive neck
Aluminum
surface
Conductive knob
Non-conductive neck
in sampled area
equals charge
Figure 6: Proof Plane in Faraday Ice Pail
