Test Bank for Physics Principles with Applications ((10))

Physics: Principles with Applications, Sixth Edition



25) If the current flowing through a circuit of constant resistance is doubled, the power dissipated
by that circuit will
A) quadruple.
B) double.
C) decrease to one half.
D) decrease to one fourth.
Answer: A
Diff: 1 Page Ref: Sec. 18.5-18.6


26) During a power demand, the voltage output is reduced by 5.0%. By what percentage is the
power on a resistor affected?
A) 2.5% less
B) 5.0% less
C) 10% less
D) 90% less
Answer: C
Diff: 2 Page Ref: Sec. 18.5-18.6


27) A current that is sinusoidal with respect to time is referred to as
A) a direct current.
B) an alternating current.
Answer: B
Diff: 1 Page Ref: Sec. 18.7


28) Consider two copper wires each carrying a current of 3.0 A. One wire has twice the diameter
of the other. The ratio of the drift velocity in the smaller diameter wire to that in the larger
diameter wire is
A) 4:1.
B) 2:1.
C) 1:2.
D) 1:4.
Answer: A
Diff: 2 Page Ref: Sec. 18.8


29) Materials in which the resistivity becomes essentially zero at very low temperatures are
referred to as
A) conductors.
B) insulators.
C) semiconductors.
D) superconductors.
Answer: D
Diff: 1 Page Ref: Sec. 18.9



347

,Chapter 18: Electric Currents



Quantitative Problems

1) What current is flowing if 0.67 C of charge pass a point in 0.30 s?
A) 2.2 A
B) 0.67 A
C) 0.30 A
D) 0.20 A
Answer: A
Diff: 1 Page Ref: Sec. 18.1


2) A charge of 12 C passes through an electroplating apparatus in 2.0 min. What is the average
current?
A) 0.10 A
B) 0.60 A
C) 1.0 A
D) 6.0 A
Answer: A
Diff: 1 Page Ref: Sec. 18.2


3) How much charge must pass by a point in 10 s for the current to be 0.50 A?
A) 20 C
B) 2.0 C
C) 5.0 C
D) 0.050 C
Answer: C
Diff: 1 Page Ref: Sec. 18.2


4) A total of 2.0 ˛ 1013 protons pass a given point in 15 s. What is the current?
A) 1.3 mA
B) 1.3 A
C) 0.21 mA
D) 3.2 mA
Answer: C
Diff: 2 Page Ref: Sec. 18.2


5) What current is flowing if 4.0 ˛ 1016 electrons pass a point in 0.50 s?
A) 0.013 A
B) 0.31 A
C) 6.3 A
D) 78 A
Answer: A
Diff: 2 Page Ref: Sec. 18.2


348

, Physics: Principles with Applications, Sixth Edition



6) If 3.0 ˛ 1015 electrons flow through a section of a wire of diameter 2.0 mm in 4.0 s, what is the
current in the wire?
A) 0.12 mA
B) 0.24 mA
C) 7.5 ˛ 107 A
D) 7.5 ˛ 1014 A
Answer: A
Diff: 2 Page Ref: Sec. 18.2


7) A coffee maker, which draws 13.5 A of current, has been left on for 10 min. What is the net
number of electrons that have passed through the coffee maker?
A) 1.5 ˛ 1022
B) 5.1 ˛ 1022
C) 1.8 ˛ 103
D) 8.1 ˛ 103
Answer: B
Diff: 2 Page Ref: Sec. 18.2


8) In an electroplating process, it is desired to deposit 40 mg of silver on a metal part by using a
current of 2.0 A. How long must the current be allowed to run to deposit this much silver?
(The silver ions are singly charged, and the atomic weight of silver is 108.)
A) 16 s
B) 18 s
C) 20 s
D) 22 s
Answer: B
Diff: 2 Page Ref: Sec. 18.2


9) What potential difference is required to cause 4.00 A to flow through a resistance of 330 W?
A) 12.1 V
B) 82.5 V
C) 334 V
D) 1320 V
Answer: D
Diff: 1 Page Ref: Sec. 18.3




349

, Chapter 18: Electric Currents



10) What is the voltage across a 5.0-W resistor if the current through it is 5.0 A?
A) 100 V
B) 25 V
C) 4.0 V
D) 1.0 V
Answer: B
Diff: 1 Page Ref: Sec. 18.3


11) A 4000-W resistor is connected across 220 V. What current will flow?
A) 0.055 A
B) 1.8 A
C) 5.5 A
D) 18 A
Answer: A
Diff: 1 Page Ref: Sec. 18.3


12) A light bulb operating at 110 V draws 1.40 A of current. What is its resistance?
A) 12.7 W
B) 78.6 W
C) 109 W
D) 154 W
Answer: B
Diff: 1 Page Ref: Sec. 18.3


13) A 12-V battery is connected to a 100-W resistor. How many electrons flow through the wire in
1.0 min?
A) 1.5 ˛ 1019
B) 2.5 ˛ 1019
C) 3.5 ˛ 1019
D) 4.5 ˛ 1019
Answer: D
Diff: 2 Page Ref: Sec. 18.3


14) What is the resistance of 1.0 m of no. 18 copper wire (diameter 0.40 in)? (The resistivity of
copper is 1.68 ˛ 10-8 Wœm.)
A) 0.00012 W
B) 0.00021 W
C) 0.0012 W
D) 0.0021 W
Answer: B
Diff: 2 Page Ref: Sec. 18.4



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