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Clayton State University
Department of Natural Sciences
November 12, 2007
Physics 1112 – Quiz 9
Name _____SOLUTION________________________________
1. A resistor is connected to an AC supply. On this circuit, the current
a. Leads the voltage by 90o.
b. Lags the voltage by 90o.
c. Is in phase with the voltage.
d. Leads the voltage by 180o.
2. Which of the following statements is correct for a series RLC circuit?
a. The voltage across the capacitor leads the voltage across
the inductor by 90o.
b. The voltage across the inductor leads the voltage across the
capacitor by 90o.
c. The voltage across the inductor leads the voltage across the
resistor by 180o.
d. The voltage across the inductor leads the voltage across the
capacitor by 180o.
3. The capacitive reactance in an ac circuit changes by what factor when the
frequency is tripled?
a. 1/3.
b. 1/9.
c. 3.
d. 9.
Clayton State University
Department of Natural Sciences
July 10, 2008
Physics 1112 – Quiz 9
Name SOLUTION_____________________________________
1. The maximum voltage produced by an ac generator is 8.00 V. What is the rms voltage?
a. 2.8 V.
b. 5.7 V.
c. 4.0 V.
d. 16.0 V
2. Which of the following is the correct expression for the SI units of the capacitive
reactance?
a. -s.
b. .
c. J-A/s.
d. J/m.
3. A resistor is connected to the ac generator. The current in the resistor
a. Is in phase with the voltage.
b. Leads the voltage by 90o.
c. Lags the voltage by 90o.
d. Lags the voltage by 180o.
Department of Natural Sciences
Clayton State University
April 16, 2012
Physics 2212 – Quiz 10
Name _SOLUTION____________________________________
1. A sinusoidally varying potential difference has amplitude 578 V.
(i)
What is its minimum instantaneous value?
a. 578 V.
b. 409 V.
c. 0.
d. -409 V.
e. -578 V.
(ii)
What is its average value?
f. 578 V.
g. 409 V.
h. 0.
i. -409 V.
j. -578 V.
(iii)
What is its rms value?
k. 578 V.
l. 409 V.
m. 0.
n. -409 V.
o. -578 V.
2. An AC source with an output rms voltage of 33.0 V at a frequency of 60.0 Hz is
connected across a 13.0-µF capacitor.
(a) Find the capacitive reactance.
XC 
1
1

 204 
C 2fC
(b) Find the rms current.
I rms 
Vrms
 0.162 A
XC
(c) Find the maximum current in the circuit.
I max  I rms 2  0.229 A
(d) Does the capacitor have its maximum charge when the current has its maximum
value?
No, in a capacitive circuit voltage (and charge on the plates of a capacitor which is
directly proportional to voltage) lags behind current.
3. In a purely inductive AC circuit as shown in the figure, ΔVmax = 100 V.
If the maximum current is 6.50 A at 55.0 Hz, calculate the inductance L.
Vmax
I max 
XL
X L  2fL 
Vmax
 15.4 
I max
L  0.0445 H