TA: Tomoyuki Nakayama
Thursday, June 3, 2010
PHY 2048: Physics 2 with Calculus, Summer C 2010
Review (Chapter 26.1- 27.9)
The purpose of this review is to refresh your memory. Physics is a cumulative subject, so make it
sure that you understand basic concepts and typical problem solving techniques in previous chapters
before moving on to a new chapter.
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A. Resistance & Resistivity
Two conductors are made of the same material and have the same length. Conductor A is a solid wire
of diameter 5.00 mm. Conductor B is a hollow tube of outside diameter 6.00 mm and inside diameter
3.00 mm. What is the resistance ratio RA/RB, measured between their ends?
B. Equivalent Resistance
In the figure below right, R1 = 6 Ω, R2 = 3 Ω and R3 = 4 Ω. Find the equivalent resistance of the
combination of the five resistors.
C. Kirchoff’s Rules
In the figure below right, R1 = 6 Ω, R2 = 3 Ω and R3 = 4 Ω. Find the equivalent resistance of the
combination of the five resistors.
D. RC Circuit
In the figure, R1 = 4 kΩ, R2 = 2 kΩ, R3 = 3 kΩ. C = 5 µF and E = 30 V. First, the switch is closed a
long time so that the steady state is reached. Then the switch is opened at time t = 0. What is the
current in resistor 2 at t = 10 ms?
TA: Tomoyuki Nakayama
Thursday, June 3, 2010
PHY 2048: Physics 2 with Calculus, Summer C 2010
Practice Exam Problems (Chapter 26.1- 27.9)
Working on this problem set is optional, but it is strongly recommended. It is quite possible that
some of these problems will appear in exams. Do it on a weekly basis. Cramming is tiring and
sometimes it ends up in a disaster.
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1. A 60-watt light bulb carries a current of 0.5 A. The total charge passing through it in one hour is:
(Electric Current) a. 120 C b. 3600 C c. 3000 C d. 2400 C e. 1800 C
2. A certain sample carries a current of 4 A when the potential difference is 2V and a current of 10 A
when the potential difference is 4V. This sample: (Ohm’s Law) a. obeys Ohm’s law b. has a
resistance of 0.5 Ω at 1 V c. has a resistance of 2.5 Ω at 1 V d. has a resistance of 2.5 Ω at 2 V e.
does not have a resistance
3. A nichrome wire is 1 m long and 1 × 10-6 m2 in cross-sectional area. When connected to a
potential difference of 2 V, a current of 4 A exists in the wire. The resistivity of this nichrome is:
(Resistivity) a. 1 × 10-7 Ω·m b. 2 × 10-7 Ω·m c. 4 × 10-7 Ω·m d. 5 × 10-7 Ω·m e. 8 × 10-7 Ω·m
4. An ordinary light bulb is marked “60 W, 120 V”. Its resistance is:
(Power) a. 60 Ω b. 120 Ω c. 180 Ω d. 240 Ω e.15 Ω
5. The current in the 5.0-Ω resistor in the circuit shown is (Equivalent
Resistance) a. 0.42 A b. 0.67 A c. 1.5 A d. 2.4 A e. 3.0 A
6. “The sum of the emf’s and potential differences around a closed loop is a consequence of :
(Kirchhoff’s Loop Rule) a. Newton’s third law b. Ohm’s law c. Newton’s second law d.
conservation of enegy e. conservation of charge
7. A portion of a circuit is shown, with the values of the currents given
for some branches. What is the direction and value of the current i?
(Kirchoff’s Junction Rule) a. ↓, 6 A b. ↑, 6 A c. ↓, 4 A d. ↑, 4 A
e. ↓, 2 A
8. A certain galvanometer has a resistance of 100 Ω and requires 1 mA for full scale deflection. To
make this into a voltmeter reading 1 V full scale, connect a resistance of: (Ammeter/Voltmeter) a.
1000 Ω in parallel b. 900 Ω in series c. 1000 Ω in series d. 10 Ω in parallel e. 0.1 Ω in series
9. In the circuit shown, both resistors have the same value R. Suppose
switch S is initially closed. When it is then opened, the circuit has a time
constant τa. Conversely, suppose S is initially open. When it is then
closed, the circuit has a time constant τb. The ratio τa/τb is: (RC Circuits)
a. 1 b. 2 c. 0.5 d. 0.667 e. 1.5
Answer: 1-e 2-b 3-d 4-d 5-c 6-d 7-a 8-b 9-b