VIII. Filters: Resistors, Capacitors, Inductors, and
AC
Circuits.
See section three starting on page 939 in Tipler's Fifth Edition for
some background.
Also, check out this website for AC: http://www.sciencejoywagon.com/physicszone/lesson/otherpub/wfendt/accircuit.htm
Equipment List:
Fluke O-Scope
HP function generator
Bread board
assorted bananas and BNC cables
one capacitor, one inductor, one resistor
Introduction:
In AC, a capacitor and an inductor can both be thought of as
"resistors"
because they can act to impede the flow of charge from an Emf. But
their
"resistances" (actually called reactances) are each a function of
frequency.
For the capacitor, the higher the frequency, the lower its resistance
to
current; for the inductor, the higher the frequency, the more it
impedes
the current. In other words, these two circuit elements behave in
opposite
manners when they act as resistors whose values are functions of the
driving
frequency. This lab tries to verify that claim and compare experimental
data
to theoretical predictions with two graphs..
Procedure:
Set up a series circuit for the capacitor and resistor. Take twenty
data
pairs of the voltage across the capacitor and the driving frequency
(calculated
from the scope). Also include the source voltage (you would not expect
it
to vary with the frequency) as a measurement from you scope.
Repeat the above for an inductor in series with the resistor (no
capacitor).
Analysis:
Use the computers to draw two separate graphs on two separte pages to
be
each taped in your lab book. One graph for the inductor circuit, and
one
graph for the capacitor circuit. Compare your graph with the
theoretical
model .
Conclusion:
Discuss any significant similarities and differences between your
results
and your expectations based on the theoretical model.
If you call the source voltage, Vin and the
voltage
across the capacitor, Vout, then you have constructed an
"RC
low pass filter circuit" of the most elementary kind. What is the
function
of the circuit that includes the inductor?