Question 1

Drift velocity: Building codes usually limit the current carried by a 1.6-mm diameter copper wire to 15 A. Many household circuits are wired with this size wire. What is the drift velocity of the electrons in this case?. Assume one conduction electron per atom in copper. The atomic weight of copper is 63.3 g/mol and its density is 8900 kg/m3. Avogadro's number is 6.022 × 1023 molecules/mol and e = 1.60 × 10-19 C.

Accepted Answer

A)   5.51 × 10-4 m/s
B)   4.56 × 10-4 m/s
C)   1.65 × 10-3 m/s
D)   4.44 × 10-2 m/s
E)   4.89 × 10-5 m/sF) All of the above
G) D) and E)

Question 2

Power: A certain electric furnace consumes 24 kW when it is connected to a 240-V line. What is the resistance of the furnace?

Accepted Answer

A)   1.0 kΩ
B)   10 Ω
C)   2.4 Ω
D)   0.42 Ω
E)   100 ΩF) C) and E)
G) A) and B)

Question 3

Drift velocity: When electric current is flowing in a metal, the electrons are moving

Accepted Answer

A)   at nearly the speed of light.
B)   at the speed of light.
C)   at the speed of sound in the metal.
D)   at the speed of sound in air.
E)   at none of the above speeds.F) A) and C)
G) B) and D)

Question 4

Current density: If a current of 2.4 A is flowing in a cylindrical wire of diameter 2.0 mm, what is the average current density in this wire?

Accepted Answer

A)   7.6 × 105 A/m2
B)   5.2 × 10-6 A/m2
C)   1.9 × 105 A/m2
D)   3.6 × 105 A/m2
E)   21 × 10-6 A/m2F) A) and B)
G) A) and C)

Question 5

Ohm's law: Two cables of the same length are made of the same material, except that 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.)

Accepted Answer

A)   The same current flows through both cables.
B)   Both cables carry the same current density.
C)   The electrons have the same drift velocity in both cables.
D)   The current in the thin cable is twice as great as the current in the thick cable.
E)   The current in the thin cable is four times as great as the current in the thick cable.F) C) and D)
G) B) and C)

Question 6

Resistivity and temperature: A Nichrome wire is used as a heating element in a toaster. From the moment the toaster is first turned on to the moment the wire reaches it maximum temperature, the current in the wire drops by 20.0% from its initial value. What is the temperature change in the wire? The temperature coefficient of resistivity for Nichrome is 0.000400 (°C) -1.

Accepted Answer

A)   200°C
B)   400°C
C)   500°C
D)   625°C
E)   300°CF) C) and D)
G) A) and C)

Question 7

Current: In a certain electroplating process gold is deposited by using a current of 14.0 A for 19 minutes. A gold ion, Au+, has a mass of approximately 3.3 × 10-22 g. How many grams of gold are deposited by this process?

Accepted Answer

A)   33 g
B)   16 g
C)   22 g
D)   28 g
E)   97 gF) B) and C)
G) D) and E)

Question 8

Electric field in a wire: A narrow copper wire of length L and radius b is attached to a 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

Accepted Answer

A)   E.
B)   2E.
C)   4E.
D)   E/2.
E)   E/4.F) A) and C)
G) A) and D)

Question 9

Basics of ac circuits: A 500-W device is connected to a 230-V ac power source. What rms current flows through this device?

Accepted Answer

A)   290 A
B)   2.2 A
C)   330 A
D)   230 A
E)   3.1 AF) D) and E)
G) A) and B)

Question 10

Resistivity and temperature: The temperature coefficient of resistivity for copper is 0.0068 (C°) -1. If a copper wire has a resistance of 104 Ω at 20°C, what is its resistance 80°C?

Accepted Answer

A)   192 Ω
B)   42 Ω
C)   71 Ω
D)   161 Ω
E)   146 ΩF) C) and E)
G) D) and E)

Question 11

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 terminal voltage Vab of the battery? ab of the battery?   A)  -30 V B)  80 V C)  30 V D)  -80 V E)  zero" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   -30 V
B)   80 V
C)   30 V
D)   -80 V
E)   zeroF) A) and B)
G) B) and E)

Question 12

Power: The resistivity of gold is 2.44 × 10-8 Ω ∙ m at room temperature. A gold wire that is 1.8 mm in diameter and 11 cm long carries a current of 170 mA. How much power is dissipated in the wire?

Accepted Answer

A)   0.030 mW
B)   0.0076 mW
C)   0.013 mW
D)   0.019 mW
E)   0.025 mWF) A) and E)
G) A) and D)

Question 13

Drift velocity: The figure shows two connected wires that are made of the same material. The current entering the wire on the left is 2.0 A and in that wire the electron drift speed is vd. What is the electron drift speed in the wire on the right side? d. What is the electron drift speed in the wire on the right side?   A)  4vd B)  2vd C)  vd D)  vd/2 E)  vd/4" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   4vd
B)   2vd
C)   vd
D)   vd/2
E)   vd/4F) B) and C)
G) B) and E)

Question 14

Current density: A certain fuse "blows" if the current in it exceeds 1.0 A, at which instant the fuse melts with a current density of  What is the diameter of the wire in the fuse?

Accepted Answer

A)   0.45 mm
B)   0.63 mm
C)   0.68 mm
D)   0.91 mmE) None of the above
F) A) and D)

Question 15

Basics of ac circuits: A 500-W device is connected to a 230-V ac power source. What peak current flows through this device?

Accepted Answer

A)   2.2 A
B)   330 A
C)   3.1 A
D)   290 A
E)   230 AF) A) and B)
G) A) and C)

Question 16

Internal battery resistance: The emf and the internal resistance of a battery are as shown in the figure. When the terminal voltage Vab is equal to 17.4 V, what is the current through the battery, including its direction? ab is equal to 17.4 V, what is the current through the battery, including its direction?   A)  6.8 A, from b to a B)  8.7 A, from b to a C)  6.8 A, from a to b D)  8.7 A, from a to b E)  16 A, from b to a" class="answers-bank-image d-inline" rel="preload" >

Accepted Answer

A)   6.8 A, from b to a
B)   8.7 A, from b to a
C)   6.8 A, from a to b
D)   8.7 A, from a to b
E)   16 A, from b to aF) D) and E)
G) A) and B)

Question 17

Drift velocity: The figure shows a steady electric current passing through a wire with a narrow region. What happens to the drift velocity of the moving charges as they go from region A to region B and then to region C?

Accepted Answer

A)   The drift velocity decreases from A to B and increases from B to C.
B)   The drift velocity increases all the time.
C)   The drift velocity remains constant.
D)   The drift velocity decreases all the time.
E)   The drift velocity increases from A to B and decreases from B to C.F) C) and D)
G) A) and B)

Question 18

Power: A light bulb is connected to a 110-V source. What is the resistance of this bulb if it is a 100-W bulb?

Accepted Answer

A)   100 Ω
B)   8.0 mΩ
C)   6.0 mΩ
D)   120 Ω
E)   240 ΩF) C) and E)
G) B) and C)

Question 19

Current: The current in a wire varies with time according to the equation I(t) = 6.00 A + ( 4.80 A/s)t, where t is in seconds. How many coulombs of charge pass a cross section of the wire in the time period between t = 0.00 s and

Accepted Answer

The answer of Current: The current in a wire varies...

Question 20

Internal battery resistance: The emf and the internal resistance of a battery are as shown in the figure. If a current of 8.3 A is drawn from the battery when a resistor R is connected across the terminals ab of the battery, what is the power dissipated by the resistor R?

Accepted Answer

A)   440 W
B)   700 W
C)   620 W
D)   530 W
E)   790 WF) All of the above
G) B) and E)

Exam 21: Electric Charge and Electric Field

Internal battery resistance: The emf and the internal resistance of a battery are as shown in the figure. If a current of 8.3 A is drawn from the battery when a resistor R is connected across the terminals ab of the battery, what is the power dissipated by the resistor R?

Correct Answer
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Correct Answer
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Current: The current in a wire varies with time according to the equation I(t) = 6.00 A + ( 4.80 A/s)t, where t is in seconds. How many coulombs of charge pass a cross section of the wire in the time period between t = 0.00 s and

Correct Answer
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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 terminal voltage V_ab of the battery?

Correct Answer
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Power: A certain electric furnace consumes 24 kW when it is connected to a 240-V line. What is the resistance of the furnace?

Correct Answer
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Current density: A certain fuse "blows" if the current in it exceeds 1.0 A, at which instant the fuse melts with a current density of What is the diameter of the wire in the fuse?

Correct Answer
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Power: The resistivity of gold is 2.44 × 10^-8 Ω ∙ m at room temperature. A gold wire that is 1.8 mm in diameter and 11 cm long carries a current of 170 mA. How much power is dissipated in the wire?

Correct Answer
verified

Drift velocity: When electric current is flowing in a metal, the electrons are moving

Correct Answer
verified

Current: In a certain electroplating process gold is deposited by using a current of 14.0 A for 19 minutes. A gold ion, Au⁺, has a mass of approximately 3.3 × 10^-22 g. How many grams of gold are deposited by this process?

Correct Answer
verified

Drift velocity: The figure shows two connected wires that are made of the same material. The current entering the wire on the left is 2.0 A and in that wire the electron drift speed is v_d. What is the electron drift speed in the wire on the right side?

Correct Answer
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Correct Answer
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Ohm's law: Two cables of the same length are made of the same material, except that 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.)

Correct Answer
verified

Internal battery resistance: The emf and the internal resistance of a battery are as shown in the figure. When the terminal voltage V_ab is equal to 17.4 V, what is the current through the battery, including its direction?

Correct Answer
verified

Power: A light bulb is connected to a 110-V source. What is the resistance of this bulb if it is a 100-W bulb?

Correct Answer
verified

Resistivity and temperature: The temperature coefficient of resistivity for copper is 0.0068 (C°) ^-1. If a copper wire has a resistance of 104 Ω at 20°C, what is its resistance 80°C?

Correct Answer
verified

Current density: If a current of 2.4 A is flowing in a cylindrical wire of diameter 2.0 mm, what is the average current density in this wire?

Correct Answer
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Drift velocity: The figure shows a steady electric current passing through a wire with a narrow region. What happens to the drift velocity of the moving charges as they go from region A to region B and then to region C?

Correct Answer
verified

Basics of ac circuits: A 500-W device is connected to a 230-V ac power source. What rms current flows through this device?

Correct Answer
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Basics of ac circuits: A 500-W device is connected to a 230-V ac power source. What peak current flows through this device?

Correct Answer
verified

Correct Answer
verified

Exam 21: Electric Charge and Electric Field

Internal battery resistance: The emf and the internal resistance of a battery are as shown in the figure. If a current of 8.3 A is drawn from the battery when a resistor R is connected across the terminals ab of the battery, what is the power dissipated by the resistor R?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Current: The current in a wire varies with time according to the equation I(t) = 6.00 A + ( 4.80 A/s)t, where t is in seconds. How many coulombs of charge pass a cross section of the wire in the time period between t = 0.00 s and

Correct AnswerverifiedShow Answer

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 terminal voltage Vab of the battery?

Correct AnswerverifiedShow Answer

Power: A certain electric furnace consumes 24 kW when it is connected to a 240-V line. What is the resistance of the furnace?

Correct AnswerverifiedShow Answer

Current density: A certain fuse "blows" if the current in it exceeds 1.0 A, at which instant the fuse melts with a current density of What is the diameter of the wire in the fuse?

Correct AnswerverifiedShow Answer

Power: The resistivity of gold is 2.44 × 10-8 Ω ∙ m at room temperature. A gold wire that is 1.8 mm in diameter and 11 cm long carries a current of 170 mA. How much power is dissipated in the wire?

Correct AnswerverifiedShow Answer

Drift velocity: When electric current is flowing in a metal, the electrons are moving

Correct AnswerverifiedShow Answer

Current: In a certain electroplating process gold is deposited by using a current of 14.0 A for 19 minutes. A gold ion, Au+, has a mass of approximately 3.3 × 10-22 g. How many grams of gold are deposited by this process?

Correct AnswerverifiedShow Answer

Drift velocity: The figure shows two connected wires that are made of the same material. The current entering the wire on the left is 2.0 A and in that wire the electron drift speed is vd. What is the electron drift speed in the wire on the right side?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Ohm's law: Two cables of the same length are made of the same material, except that 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.)

Correct AnswerverifiedShow Answer

Internal battery resistance: The emf and the internal resistance of a battery are as shown in the figure. When the terminal voltage Vab is equal to 17.4 V, what is the current through the battery, including its direction?

Correct AnswerverifiedShow Answer

Power: A light bulb is connected to a 110-V source. What is the resistance of this bulb if it is a 100-W bulb?

Correct AnswerverifiedShow Answer

Resistivity and temperature: The temperature coefficient of resistivity for copper is 0.0068 (C°) -1. If a copper wire has a resistance of 104 Ω at 20°C, what is its resistance 80°C?

Correct AnswerverifiedShow Answer

Current density: If a current of 2.4 A is flowing in a cylindrical wire of diameter 2.0 mm, what is the average current density in this wire?

Correct AnswerverifiedShow Answer

Drift velocity: The figure shows a steady electric current passing through a wire with a narrow region. What happens to the drift velocity of the moving charges as they go from region A to region B and then to region C?

Correct AnswerverifiedShow Answer

Basics of ac circuits: A 500-W device is connected to a 230-V ac power source. What rms current flows through this device?

Correct AnswerverifiedShow Answer

Basics of ac circuits: A 500-W device is connected to a 230-V ac power source. What peak current flows through this device?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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Correct Answer
verified

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 terminal voltage V_ab of the battery?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Power: The resistivity of gold is 2.44 × 10^-8 Ω ∙ m at room temperature. A gold wire that is 1.8 mm in diameter and 11 cm long carries a current of 170 mA. How much power is dissipated in the wire?

Correct Answer
verified

Correct Answer
verified

Current: In a certain electroplating process gold is deposited by using a current of 14.0 A for 19 minutes. A gold ion, Au⁺, has a mass of approximately 3.3 × 10^-22 g. How many grams of gold are deposited by this process?

Correct Answer
verified

Drift velocity: The figure shows two connected wires that are made of the same material. The current entering the wire on the left is 2.0 A and in that wire the electron drift speed is v_d. What is the electron drift speed in the wire on the right side?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Internal battery resistance: The emf and the internal resistance of a battery are as shown in the figure. When the terminal voltage V_ab is equal to 17.4 V, what is the current through the battery, including its direction?

Correct Answer
verified

Correct Answer
verified

Resistivity and temperature: The temperature coefficient of resistivity for copper is 0.0068 (C°) ^-1. If a copper wire has a resistance of 104 Ω at 20°C, what is its resistance 80°C?

Correct Answer
verified

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
verified

Correct Answer
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