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Model No. ES-9080
Basic Electrostatics System
29
3D.1: Capacitors in Series
Make sure all capacitors are uncharged before connecting them. (Use a
short wire to momentarily short each one.)
1.
Set up the series circuit, as shown in Figure 3.7a.
2.
Plug in to the 30 VDC output on the Voltage Source. Close switch A
to charge capacitor C1.
3.
Using the known value of C
1
, calculate the initial amount of charge
on C
1
. Let’s call it Q
o
. (Remember Q=CV.)
4.
Throw the switch to position B. C
1
and C
2
are now in series.
5.
Use the electrometer to measure the voltage drop across each of the
capacitors (V
1
and V
2
).
6.
Using the known values of capacitance, determine the amount of
charge in each of them. (Q
1
and Q
2
).
7.
Questions: Can you find a relation between V
1
, V
2
and the voltage
of the source? How does Q
1
and Q
2
relate to the original charge on
C
1
?
3D.2: Capacitors in Parallel
1.
Make sure all capacitors are uncharged before connecting them to the
circuit.
2.
Set up the parallel circuit, as shown in Figure 3.7b.
3.
Set the voltage source to 30 VDC. Close the switch to charge the
capacitors.
4.
Use the electrometer to measure the potential difference across
each of the capacitors. How does it compare to the voltage of the
source?
5.
Use the known value of the capacitances to determine the charge in
each capacitor. How are the charges related?
Analysis:
1.
Compare series and parallel capacitors in terms of charges, voltages
and capacitance.
