Basic Electrostatics System
Model No. ES-9080
10
!
Faraday Ice Pail (ES-9042A)
The PASCO Faraday Ice Pail is
shown in Figure 8. Originally
designed by Michael Faraday, it
works on the principle that any
charge placed inside a conducting
surface will induce an equal
charge on the outside of the
surface. It is an excellent product
for sampling charges and charge
distributions. The PASCO version
illustrated above consists of two
wire mesh cylinders, one inside
the other, mounted on a molded
plastic bottom.
The outer cylinder is called
the shield. It provides
complete visibility to the
inside of the pail and, when
grounded, helps eliminate
stray charges and AC
fields. The inner cylinder is
the actual pail. The pail is
mounted on insulated rods;
the pail is 10 cm in
diameter and 15 cm high.
When a charged object is
placed inside the pail, but without touching it, a charge of the same
magnitude is induced on the outside of the pail. (See Figure 9). An
electrometer connected between the pail and the shield will detect a
potential difference. The greater the charge, the greater the potential
difference. So even though the electrometer will give readings of
voltage, it is possible to use those values as relative charge
measurements.
To prevent stray charges from producing erroneous results, it is
extremely important that the Faraday Ice Pail be momentarily
grounded prior to starting any experiment. The demonstrator must also
be continually grounded while performing an experiment.
The Charge Producers are used as charged objects to lower into the ice
pail. The Proof Planes are used to sample surface charge densities.
Figure 8: Faraday
Ice Pail
shield
pail
insulators
Figure 9: Charge Induction
red lead
black lead
