Basic Electrostatics System
Model No. ES-9080
8
!
Here are some guidelines in the proper use and care of the charge
producers that are important to remember:
• If a zero charge is desirable, discharge the charge producers by
touching the conductive disk to ground. To be sure the disk is fully
discharged, gently breathe on the non-conductive neck. The moisture
from your breath will help remove any stray charge.
• 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 insulator shafts 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 disk. The
nonconductive neck is white
polycarbonate (about 10
14
:
).
The proof plane is used to
sample the charge density on charged conductive surfaces. A Faraday
Ice Pail can then be used to measure the charge density on the proof
plane.
Figure 5: Proof Plane
handle
surface
aluminum
(white)
non-conductive neck
(black)
conductive disk
NOTE:
The proof
planes can be used to
test for charge polarity
on conductors of any
shape. However, for
accurate readings of
charge density, the con-
ductor surface sam-
pled has to be
considerably larger
than the disk of the
proof plane and have a
relatively large radius
of curvature at the
point of contact.