PASCO ES-9042A Instruction Sheet

Instruction Sheet
for the PASCO
Model ES-9042A
Introduction
The Ice Pail designed by Faraday is an excellent product
for sampling a charge distribution. It operates on the
principle that a charge placed inside a conducting sur-
face will induce an equal charge on the outside of that
surface. For example, if a charged ball were hung inside
a coffee can, the charge on the outside of the can would
equal the charge of the ball. The charge can be measured
with an electrometer such as the PASCO Model ES-9078
Basic Electrometer.
The PASCO Model
ES-9042A Faraday Ice Pail
is a wire mesh cylinder
measuring 10 cm in diam-
eter by 15 cm deep with a
wire mesh bottom. It is
mounted on three insulating
rods along the outer edge of
a wire mesh shield.
The wire mesh shield not
only ensures complete vis-
ibility of the experiment but
also helps eliminate the
problem of stray charges and AC fields.
To prevent stray charges from producing erroneous re-
sults it is extremely important that the person performing
the experiment be continually grounded while perform-
ing the experiment. The Ice-Pail needs to be temporarily
grounded prior to starting the experiment.
A charged object such as the PASCO Model ES-9057A
Charge Producers and Proof Plane is placed in the
grounded ice pail (without touching it), and the elec-
trometer indicates the potential between the ice pail and
ground. The greater the charge the greater the potential.
Thus we can easily measure relative charges by varying
the charges in the ice pail and observing the potential
indicated by the electrometer.
Faraday Ice Pail
Complete instructions for the operation of PASCO Elec-
trostatic equipment can be found in the ES-9051 Acces-
sory and Demonstration Manual (included with the
Demonstration System) and the ES-9055 Laboratory
Manual (included with the Electrostatic Laboratory Sys-
tem)
Demonstration: Faraday Ice Pail and Charge
Production
Since the Faraday Ice Pail is used so frequently in elec-
trostatic demonstrations, one should examine the rela-
tionship between the charge induced on the ice pail by
an inserted object and the actual charge on that object.
Using the ice pail, one can then investigate the nature of
charging an object by contact as opposed to charging by in-
duction.
Equipment needed: Faraday Ice Pail, charge producing ob-
jects (such as ES-9057A Charge Producers), electrometer
Setup
Electrometer
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Black Clip
Faraday Ice Pail
Figure 1
Connect the electrometer input lead (red alligator
clip) to the ice pail to create a system for measuring
charge. The electrometer ground lead (black alligator
clip) attaches to the shield. (Setup is shown in Figure
1.) Adjust the sensitivity of the electrometer so that
most readings appear in the upper 2/3 of the scale.
012-04393C
Charge Producer
Red Clip
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