PASCO ES-9060 Charge, Equipotential and Field Mapper - Manual (Page 15)

Charge, Equipotential, and Field Mapper Model No. ES-9060
14 ®
Experiment 9: Triode
Equipment required: 5 K
Potentiometer
Use a 5 K Potentiometer to provide
three potentials. Connect the three
short electrodes with wires “a.”
Do not let these wires touch the
black paper except at the
conductive ink electrodes.
Questions:
a) How is the field in the area between the short electrodes affected by
the potential between the short electrodes and the closer, long
electrode?
b) Could this paper model of a triode act as an amplifying device? If
not, why not?
Experiment 10: Fluid Mechanics Experiments
The PASCO Field Mapper can also be used to examine fluid flow. In
many fluid systems, the velocity potential satisfies the Laplace
equations (so does the electromagnetic potential). Consequently, there
is a direct analogy between fluid flow and electric fields. In particular,
the velocity potential of an incompressible fluid where the flow is both
steady and not rotational satisfies the Laplace equation. A steady flow
of water is a good approximation of this type of flow. Now the flow is
generated by “sources” which supply the fluid and “sinks” which
absorb the fluid. We are interested in “streamlines,” which can be
thought of as lines traced out by a particular particle in the fluid. The
streamlines begin at the sources and end at the sinks.
With the Field Mapper, we need to
draw electrodes in the shape of the
sources and sinks in the fluid flow
to be examined. Then the electric
field lines which we plot coincide
with the streamlines in the fluid
flow. (Remember that the electric
field lines are perpendicular to the
equipotential lines.) If there is
some fixed obstruction in the fluid
flow, we can represent it by cutting the same shape from the
conductive paper. The schematic drawing shows a fluid flow which is
analogous to the flow in a section of pipe (with frictionless walls). The
a
a
+
Schematic 9
5K Potentiometer
+
-
Schematic 10
cut-out
shape