Dr. Tabitha Buchler
Fall 2014
Phvsics 2220
Name:
Exam 4
Unid:
1
Discussion TA:
SHOW ALL WORK!
A 12 volt battery is connected to two resistors (R/ = 5.00 Q and R2 = 7.00 fl) and an inductor (L = 3.00 mH). Switch S
has been open for a long time and is closed at time t = 0 s.
A.
B.
C.
D.
flOpts.J What is the magnitude of the current Ii immediately after the switch is closed?
[15 pts.J What is the magnitude ofdli/dt immediately after the switch is closed?
flOpts.J What is the magnitude of the current IL after the switch has been closed for a long time?
flOpts.J After the switch has been closed for a long time, it is opened. The current IL now decays
exponentially as a function of time. What is the value of the time constant of this decay?
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Fhvsics 2220
Spring 2014
Dr. Tabitha Buchler
Name:
Unid:
Discussion TA: M r
Exam 4
2
SHOW ALL WORK!
The switch in the figure has been in position a for a long time, completely charging the capacitor. At time / = 0 s, the
switch is moved to position b. Let Ift) be the current through the inductor. Let e = 9.00 V, L = 8.00 mH, and C = 20 uF.
A.
B.
fl3pts.J What is the maximum magnitude of 7?
[12 pts.J Find the earliest time after t = 0 s that the magnitude of the current I is at its maximum value. It may
help to sketch the current as a function of time.
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Physics 2220
Spring 2014
Dr. Tabitha Buehler
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Name:
3
Exam 4
Unid:
Discussion TA:
SHOW ALL WORK!
The next three questions refer to the RLC circuit shown in the figure. Let e = 200 sin(o)/) volts, L = 5.00 mH,
C = 10.0 uF, and R = 30.0 Q.
A.
B.
C.
flOpts.J At what frequency, in Hertz, is Ims maximum?
flOpts.J What is the maximum possible magnitude of Irms7
flOpts.J Is the current through the capacitor leading, lagging, or in phase
with the voltage across the resistor? Explain how you know this.
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