Physics for Scientists & Engineers with Modern Physics (Volume 2) 5e Test Bank
(Global Edition) By Douglas C. Giancoli (Answers At The End Of Each Chapter)
Chapter 21
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Internal battery resistance: In the figure, when the terminal voltage Vab of the battery is 1)
equal to 20 V, how much current passes through the battery, including its direction?
A) 6 A, from a to b
B) 5 A, from a to b
C) 4 A, from b to a
D) 5 A, from b to a
E) 4 A, from a to b
2) Internal battery resistance: The emf and the internal resistance of a battery are as shown 2)
in the figure. When the terminal voltage Vab is equal to 17.4 V, what is the current throug
battery, including its direction?
A) 6.8 A, from b to a
B) 8.7 A, from b to a
C) 16 A, from b to a
D) 6.8 A, from a to b
E) 8.7 A, from a to b
3) Current density: A proton beam that carries a total current of 1.3 mA has 10.0 mm 3)
diameter. The current density in the proton beam increases linearly with distance from
the center. This is expressed mathematically as J(r) = J0 (r/R), where R is the radius of
the beam and J0 is the current density at the edge. Determine the value of J0.
A) 6.2 A/m2 B) 17 A/m2 C) 25 A/m2 D) 12 A/m2
1
,4) Current: The figure shows a 2.0-cm diameter roller that turns at 90 rpm. A 4.0-cm wide 4)
plastic film is being wrapped onto the roller, and this plastic carries an excess electric
charge having a uniform surface charge density of 5.0 nC/cm2. What is the current of the
moving film?
A) 11 µA B) 23 µA C) 190 nA D) 30 nA
5) Basics of ac circuits: A 500-W device is connected to a 120-V ac power source. What 5)
peak current flows through this device?
A) 150 A B) 120 A C) 4.2 A D) 170 A E) 5.9 A
6) Power: The voltage and power ratings of a particular light bulb, which are its normal 6)
operating values, are 110 V and 60 W. Assume the resistance of the filament of the bulb
is constant and is independent of operating conditions. If the light bulb is operated with a
current that is 50% of the current rating of the bulb, what is the actual power drawn by
the bulb?
A) 15 W B) 10 W C) 20 W D) 30 W E) 25 W
7) Power: The resistivity of gold is 2.44 × 10-8 Ω · m at room temperature. A gold wire that 7)
is 1.8 mm in diameter and 11 cm long carries a current of 170 mA. How much power is
dissipated in the wire?
A) 0.013 mW
B) 0.030 mW
C) 0.0076 mW
D) 0.025 mW
E) 0.019 mW
8) Drift velocity: A silver wire has a cross sectional area A = 2.0 mm2. A total of 9.4 ×
8)
1018 electrons pass through the wire in 3.0 s. The conduction electron density in silver is
5.8 × 1028 electrons/m3 and e = 1.60 × 10-19 C. What is the drift velocity of these
electrons?
A) 5.2 × 10-5 m/s
B) 7.4 × 10-5 m/s
C) 2.7 × 10-5 m/s
D) 1.1 × 10-5 m/s
E) 9.1 × 10-5 m/s
2
, 9) Current density: If a current of 2.4 A is flowing in a cylindrical wire of diameter 2.0 mm, 9)
what is the average current density in this wire?
A) 21 × 10-6 A/m2
B) 1.9 × 105 A/m2
C) 3.6 × 105 A/m2
D) 7.6 × 105 A/m2
E) 5.2 × 10-6 A/m2
10) Power: A certain electric furnace consumes 24 kW when it is connected to a 240-V line. 10)
What is the resistance of the furnace?
A) 1.0 kΩ B) 100 Ω C) 2.4 Ω D) 0.42 Ω E) 10 Ω
11) Current density: A certain fuse "blows" if the current in it exceeds 1.0 A, at which instant
11)
the fuse melts with a current density of620 A/cm2. What is the diameter of the wire in
the fuse?
A) 0.45 mm B) 0.91 mm C) 0.68 mm D) 0.63 mm
12) Power: A 1500-W heater is connected to a 120-V line. How much heat energy does it
12)
produce in 2.0 hours?
A) 11 MJ B) 1.5 kJ C) 0.18 MJ D) 18 MJ E) 3.0 kJ
13) Ohm's law: Two cables of the same length are made of the same material, except that
13)
one cable has twice the diameter of the other cable. When the same potential difference
is maintained across both cables, which of the following statements are true? (There may
be more than one correct choice.)
A) The current in the thin cable is twice as great as the current in the thick cable.
B) Both cables carry the same current density.
C) The current in the thin cable is four times as great as the current in the thick cable.
D) The electrons have the same drift velocity in both cables.
E) The same current flows through both cables.
14) Internal battery resistance: The emf and the internal resistance of a battery are shown in
the figure. If a current of 7.8 A is established through the battery from b to a, what is the 14)
terminal voltage Vab of the battery?
A) -80 V B) -30 V C) 80 V D) zero E) 30 V
3
, 15) Ohm's law: When a voltage difference is applied to a piece of metal wire, a 5.0-mA 15)
current flows through it. If this metal wire is now replaced with a silver wire having
twice the diameter of the original wire, how much current will flow through the silver
wire? The lengths of both wires are the same, and the voltage difference remains
unchanged. (The resistivity of the original metal is 1.68 × 10-8 Ω · m, and the resistivity
of silver is 1.59 × 10-8 Ω · m.)
A) 19 mA B) 5.3 mA C) 11 mA D) 21 mA
16) Current: In an electroplating process, copper (ionic charge +2e, atomic weight 63.6 16)
g/mol) is deposited using a current of 10.0 A. What mass of copper is deposited in 10.0
minutes? Avogadro's number is 6.022 × 1023 molecules/mol and e = 1.60 × 10-19 C.
A) 0.99 g B) 2.52 g C) 1.52 g D) 3.96 g E) 1.98 g
17) Power: A light bulb is connected to a 110-V source. What is the resistance of this bulb if 17)
it is a 100-W bulb?
A) 6.0 mΩ B) 120 Ω C) 240 Ω D) 8.0 mΩ E) 100 Ω
18) Power: A 110-V hair dryer is rated at 1200 W. What current will it draw when operating 18)
from a 110-V electrical outlet?
A) 14 A B) 5.0 A C) 90 mA D) 1.0 A E) 11 A
19) Power: The voltage and power ratings of a particular light bulb, which are its normal 19)
operating values, are 110 V and 60 W. Assume the resistance of the filament of the bulb
is constant and is independent of operating conditions. If the light bulb is operated at a
reduced voltage and the power drawn by the bulb is 36 W, what is the operating voltage
of the bulb?
A) 85 V B) 66 V C) 78 V D) 72 V E) 90 V
20) Resistivity: What length of a certain metal wire of diameter 0.15 mm is needed for the 20)
wire to have a resistance of 15 Ω? The resistivity of this metal is 1.68 × 10-8 Ω · m.
A) 1.6 m B) 16 cm C) 16 m D) 16 mm E) 160 m
21) Electric field in a wire: A narrow copper wire of length L and radius b is attached to a 21)
wide copper wire of length L and radius 2b, forming one long wire of length 2L. This
long wire is attached to a battery, and a current is flowing through it. If the electric field
in the narrow wire is E, the electric field in the wide wire is
A) 4E. B) E/2. C) E. D) E/4. E) 2E.
4
(Global Edition) By Douglas C. Giancoli (Answers At The End Of Each Chapter)
Chapter 21
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Internal battery resistance: In the figure, when the terminal voltage Vab of the battery is 1)
equal to 20 V, how much current passes through the battery, including its direction?
A) 6 A, from a to b
B) 5 A, from a to b
C) 4 A, from b to a
D) 5 A, from b to a
E) 4 A, from a to b
2) Internal battery resistance: The emf and the internal resistance of a battery are as shown 2)
in the figure. When the terminal voltage Vab is equal to 17.4 V, what is the current throug
battery, including its direction?
A) 6.8 A, from b to a
B) 8.7 A, from b to a
C) 16 A, from b to a
D) 6.8 A, from a to b
E) 8.7 A, from a to b
3) Current density: A proton beam that carries a total current of 1.3 mA has 10.0 mm 3)
diameter. The current density in the proton beam increases linearly with distance from
the center. This is expressed mathematically as J(r) = J0 (r/R), where R is the radius of
the beam and J0 is the current density at the edge. Determine the value of J0.
A) 6.2 A/m2 B) 17 A/m2 C) 25 A/m2 D) 12 A/m2
1
,4) Current: The figure shows a 2.0-cm diameter roller that turns at 90 rpm. A 4.0-cm wide 4)
plastic film is being wrapped onto the roller, and this plastic carries an excess electric
charge having a uniform surface charge density of 5.0 nC/cm2. What is the current of the
moving film?
A) 11 µA B) 23 µA C) 190 nA D) 30 nA
5) Basics of ac circuits: A 500-W device is connected to a 120-V ac power source. What 5)
peak current flows through this device?
A) 150 A B) 120 A C) 4.2 A D) 170 A E) 5.9 A
6) Power: The voltage and power ratings of a particular light bulb, which are its normal 6)
operating values, are 110 V and 60 W. Assume the resistance of the filament of the bulb
is constant and is independent of operating conditions. If the light bulb is operated with a
current that is 50% of the current rating of the bulb, what is the actual power drawn by
the bulb?
A) 15 W B) 10 W C) 20 W D) 30 W E) 25 W
7) Power: The resistivity of gold is 2.44 × 10-8 Ω · m at room temperature. A gold wire that 7)
is 1.8 mm in diameter and 11 cm long carries a current of 170 mA. How much power is
dissipated in the wire?
A) 0.013 mW
B) 0.030 mW
C) 0.0076 mW
D) 0.025 mW
E) 0.019 mW
8) Drift velocity: A silver wire has a cross sectional area A = 2.0 mm2. A total of 9.4 ×
8)
1018 electrons pass through the wire in 3.0 s. The conduction electron density in silver is
5.8 × 1028 electrons/m3 and e = 1.60 × 10-19 C. What is the drift velocity of these
electrons?
A) 5.2 × 10-5 m/s
B) 7.4 × 10-5 m/s
C) 2.7 × 10-5 m/s
D) 1.1 × 10-5 m/s
E) 9.1 × 10-5 m/s
2
, 9) Current density: If a current of 2.4 A is flowing in a cylindrical wire of diameter 2.0 mm, 9)
what is the average current density in this wire?
A) 21 × 10-6 A/m2
B) 1.9 × 105 A/m2
C) 3.6 × 105 A/m2
D) 7.6 × 105 A/m2
E) 5.2 × 10-6 A/m2
10) Power: A certain electric furnace consumes 24 kW when it is connected to a 240-V line. 10)
What is the resistance of the furnace?
A) 1.0 kΩ B) 100 Ω C) 2.4 Ω D) 0.42 Ω E) 10 Ω
11) Current density: A certain fuse "blows" if the current in it exceeds 1.0 A, at which instant
11)
the fuse melts with a current density of620 A/cm2. What is the diameter of the wire in
the fuse?
A) 0.45 mm B) 0.91 mm C) 0.68 mm D) 0.63 mm
12) Power: A 1500-W heater is connected to a 120-V line. How much heat energy does it
12)
produce in 2.0 hours?
A) 11 MJ B) 1.5 kJ C) 0.18 MJ D) 18 MJ E) 3.0 kJ
13) Ohm's law: Two cables of the same length are made of the same material, except that
13)
one cable has twice the diameter of the other cable. When the same potential difference
is maintained across both cables, which of the following statements are true? (There may
be more than one correct choice.)
A) The current in the thin cable is twice as great as the current in the thick cable.
B) Both cables carry the same current density.
C) The current in the thin cable is four times as great as the current in the thick cable.
D) The electrons have the same drift velocity in both cables.
E) The same current flows through both cables.
14) Internal battery resistance: The emf and the internal resistance of a battery are shown in
the figure. If a current of 7.8 A is established through the battery from b to a, what is the 14)
terminal voltage Vab of the battery?
A) -80 V B) -30 V C) 80 V D) zero E) 30 V
3
, 15) Ohm's law: When a voltage difference is applied to a piece of metal wire, a 5.0-mA 15)
current flows through it. If this metal wire is now replaced with a silver wire having
twice the diameter of the original wire, how much current will flow through the silver
wire? The lengths of both wires are the same, and the voltage difference remains
unchanged. (The resistivity of the original metal is 1.68 × 10-8 Ω · m, and the resistivity
of silver is 1.59 × 10-8 Ω · m.)
A) 19 mA B) 5.3 mA C) 11 mA D) 21 mA
16) Current: In an electroplating process, copper (ionic charge +2e, atomic weight 63.6 16)
g/mol) is deposited using a current of 10.0 A. What mass of copper is deposited in 10.0
minutes? Avogadro's number is 6.022 × 1023 molecules/mol and e = 1.60 × 10-19 C.
A) 0.99 g B) 2.52 g C) 1.52 g D) 3.96 g E) 1.98 g
17) Power: A light bulb is connected to a 110-V source. What is the resistance of this bulb if 17)
it is a 100-W bulb?
A) 6.0 mΩ B) 120 Ω C) 240 Ω D) 8.0 mΩ E) 100 Ω
18) Power: A 110-V hair dryer is rated at 1200 W. What current will it draw when operating 18)
from a 110-V electrical outlet?
A) 14 A B) 5.0 A C) 90 mA D) 1.0 A E) 11 A
19) Power: The voltage and power ratings of a particular light bulb, which are its normal 19)
operating values, are 110 V and 60 W. Assume the resistance of the filament of the bulb
is constant and is independent of operating conditions. If the light bulb is operated at a
reduced voltage and the power drawn by the bulb is 36 W, what is the operating voltage
of the bulb?
A) 85 V B) 66 V C) 78 V D) 72 V E) 90 V
20) Resistivity: What length of a certain metal wire of diameter 0.15 mm is needed for the 20)
wire to have a resistance of 15 Ω? The resistivity of this metal is 1.68 × 10-8 Ω · m.
A) 1.6 m B) 16 cm C) 16 m D) 16 mm E) 160 m
21) Electric field in a wire: A narrow copper wire of length L and radius b is attached to a 21)
wide copper wire of length L and radius 2b, forming one long wire of length 2L. This
long wire is attached to a battery, and a current is flowing through it. If the electric field
in the narrow wire is E, the electric field in the wide wire is
A) 4E. B) E/2. C) E. D) E/4. E) 2E.
4
