Name: ________________________ Class: ___________________ Date: __________
Exam 2--PHYS 102--S15
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. A parallel-plate capacitor initially has a potential
difference of 200 V and is then disconnected from
the charging battery. If the distance between the
plates is now doubled, what is the new value of the
voltage?
a.
b.
c.
d.
3. The capacitance of a parallel-plate capacitor can be
increased by:
I. increasing the charge
II. decreasing the charge
III. increasing the plate separation
IV. decreasing the plate separation
V. decreasing the plate area
a. II & III
b. only IV
c. I & IV
d. II & V
200 V
400 V
100 V
800 V
2.
This figure shows a capacitor with plates of area
A=0.2 m2 and distance between the plates
d=1.2x10-6 m. If an insulator, whose dielectric
constant is 5, is placed between the plates, what is
the capacitance?
a.
b.
c.
d.
e.
4. What is the voltage across the 6 µF capacitor?
24 µF
1.5 µF
120 µF
2.7x10-16 F
7.4 µF
a.
b.
c.
d.
1
9V
6V
18 V
3V
5. What is the equivalent capacitance of this circuit?
8. Current has these basic SI units:
a. volts/meter
b. volts/farad
c. newtons/second
d. tesla*meter
e. coulombs/second
9. A 10-ohm resistor has a constant current.If 1200 C
of charge flow through it in 4 minutes what is the
value of the current?
a.
b.
c.
d.
a.
b.
c.
d.
e.
8 µF
12 µF
15 µF
2 µF
5.0 A
3.0 A
11 A
20 A
15 A
10. Which of these statements, about the use of
voltmeters and ammeters, is correct?
I. Voltmeters have a large resistance and are
connected in parallel.
II. Voltmeters have a small resistance and are
connected in parallel.
III. Ammeters have a large resistance and are
connected in series.
IV. Ammeters have a large resistance and are
connected in parallel.
V. Voltmeters have a small resistance and are
connected in series.
a. I only
b. I & III
c. III only
d. II & IV
e. V only
6. For the previous circuit, what is the voltage across
the 3µF capacitor?
a. 3 V
b. 6 V
c. 4 V
d. 2 V
e. 12 V
7. Consider this circuit. What is the energy stored on
the topmost 2 µF capacitor (circled here)?
11. A flat iron is marked “120 V,600 W.” In normal
use, the current in it is:
a.
b.
c.
d.
e.
a.
b.
c.
d.
e.
144 µJ
12 µJ
24 µJ
16 µJ
288 µJ
2
2A
4A
5A
7.2 A
0.2 A
15. A battery has an internal resistance of 0.5 Ω.
When it provides a current of 4 A, the potential
across the battery is 10 V. What is the ideal
electromotive force provided by the battery?
12. A current of 20 A flows through a wire of length 1
m and cross-sectional area 7.85x10 -7 m2. The
potential across the wire is 1.4 V. From this table
of resistivities, select the material of the wire:
Material
Copper
Silver
Gold
Tungsten
Iron
a.
b.
c.
d.
e.
Resistivity(Ohm-m)
1.7x10-8
1.59x10-8
2.44x10-8
5.5x10-8
10.0x10-8
a.
b.
c.
d.
Copper
Silver
Gold
Tungsten
Iron
20 V
8V
12 V
14 V
16. Which of these rules for resistors in series is not
correct?
I. Resistors in series must have the same current.
II. Resistors in series must have the same voltage.
III. For resistors in series, the total voltage across
the resistors is equal to the sum of the voltage
across the individual resistors.
IV. For resistors in series, the equivalent resistance
is equal to the sum of the indiviual resistors
a. II only
b. II & III
c. I & III
d. I & IV
e. II & IV
13. For a cylindrical resistor made of ohmic material,
the resistance does NOT depend on:
a. the current
b. the radius of the cylinder
c. the cross-sectional area
d. the resistivity
e. the length
14. Which of the following best describes the purpose
of resistors?
a. turn a circuit on or off.
b. act as a timing device within a circuit.
c. slow the flow of electricity.
d. store electrical energy.
3
17. What is the voltage across R 2 in this circuit:
a.
b.
c.
d.
19. Consider this circuit; the first 3 Ω resistor has a
voltage of 6 V, as labeled. What is the voltage
across the 6 Ω resistor?
a.
b.
c.
d.
e.
2V
4V
8V
10 V
18. What is the total current, I, for this circuit?
2V
6V
12 V
3V
18 V
20. For the above circuit, what is the equivalent
resistance?
a. 11 Ω
b. 6 Ω
c. 2 Ω
d. 4 Ω
e. 5 Ω
21. Consider this circuit.What is the current through
the 1Ω resistor?
a.
b.
c.
d.
36 A
9A
2A
54 A
a.
b.
c.
d.
e.
4
2A
3A
4A
6A
8A
22. Which of these resistors has the smallest current?
a.
b.
c.
d.
24. On a circuit breaker, you have a 1200 W heater, a
60 W light bulb, and a 240 W radio. When you add
a 180 W blender, the circuit breaker turns off.
Assume all the devices operate at 120 V. Which of
these is the maximum allowed current for the
breaker?
a.
b.
c.
d.
R1
R2
R3
R5
25. What purpose does the third prong on a
three-prong outlet serve?
a.
b.
23. Which of these statements about a household
circuit is true:
I. The household circuit is a series circuit.
II. All devices in a household circuit operate at the
same current.
III. As you add more devices to a household circuit,
the total current increases.
IV. A ground fault circuit interrupt turns off if
Iin>Iout for any particular device.
a.
b.
c.
d.
10 A
20 A
16 A
13 A
No purpose
Act as a ground thus providing a safety
feature
c.
An alternative to the European system of
electrical outlets
d.
Allow for more stability in the outlet
26. This is a free question. Please bubble “A” for this
question.
a. A
b. B
c. C
d. D
I & IV
III
III & IV
II & III
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ID: A
Exam 2--PHYS 102--S15
Answer Section
MULTIPLE CHOICE
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