Question 1

What is the voltage drop across a 5.0-Ω resistor if the current through it is 5.0 A?

Accepted Answer

A)  100 V 
B)  25 V 
C)  4.0 V 
D)  1.0 V 
A)  100 V 
B)  25 V 
C)  4.0 V 
D)  1.0 V

Question 2

A 200-Ω resistor is rated at 1/4 W. What is the maximum voltage that can safely be connected across it?

Accepted Answer

A)  0.71 V 
B)  7.1 V 
C)  50 V 
D)  0.25 V 
A)  0.71 V 
B)  7.1 V 
C)  50 V 
D)  0.25 V

Question 3

A 100-W driveway light bulb is on 10 hours per day. If the power company charges 10¢ for each kilowatt-hour of electricity used, estimate the yearly cost to operate the bulb if it is used every day for a 365-day year.

Accepted Answer

A)  $3.65 
B)  $7.30 
C)  $37 
D)  $73 
A)  $3.65 
B)  $7.30 
C)  $37 
D)  $73

Question 4

The length of a certain wire is doubled and at the same time its radius is reduced by a factor of 2. What is the new resistance of this wire?

Accepted Answer

A)  It is 2 times as large. 
B)  It is 4 times as large. 
C)  It is 6 times as large. 
D)  It it 8 times as large. 
E)  It is 1/2 as large. 
A)  It is 2 times as large. 
B)  It is 4 times as large. 
C)  It is 6 times as large. 
D)  It it 8 times as large. 
E)  It is 1/2 as large.

Question 5

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? (e = 1.60 × 10-19 C)

Accepted Answer

A)  0.12 mA 
B)  0.24 mA 
C)  7.5 × 107 A 
D)  7.5 × 1014 A 
A)  0.12 mA 
B)  0.24 mA 
C)  7.5 × 107 A 
D)  7.5 × 1014 A

Question 6

When a 14.0-A current flows through an 8.00-Ω device for 24.0 hours, how much does this cost if energy costs $0.0900 per kW ∙ h?

Accepted Answer

A)  $0.24 
B)  $1.04 
C)  $2.16 
D)  $3.39 
A)  $0.24 
B)  $1.04 
C)  $2.16 
D)  $3.39

Question 7

A battery is rated such that it provides $1.0 \mathrm {~mW}$ of power at $9.0 \mathrm {~V}$ when fully charged. How much current can it deliver?

Accepted Answer

A)  0.11 mA 
B)  81 kA 
C)  0.33 mA 
D)  9.1 kA 
A)  0.11 mA 
B)  81 kA 
C)  0.33 mA 
D)  9.1 kA

Question 8

An instrument is rated at 250 W if it is connected across a 120-V dc power supply.
(a) What current does it draw under normal operation?
(b) What is its resistance?
(c) How many kilowatt-hours does it use in a day if it is left on all the time?

Accepted Answer

(a) 2.1 A

Question 9

When a potential difference is applied across a piece of wire made of metal A, a $5.0 - m A$ current flows. If the metal-A wire is replaced with a wire made of metal B having twice the diameter of the metal-A wire, how much current will flow through the metal-B wire? The lengths of both wires are the same, and the voltage difference remains unchanged. The resistivity of metal A is 1.68 × 10-8 Ω ∙ m, and the resistivity of metal B is 1.59 × 10-8 Ω ∙ m.

Accepted Answer

A)  21 mA 
B)  19 mA 
C)  11 mA 
D)  5.3 mA 
A)  21 mA 
B)  19 mA 
C)  11 mA 
D)  5.3 mA

Question 10

How much energy does a 100-W light bulb use in 8.0 hours?

Accepted Answer

A)  0.0080 kWh 
B)  0.80 kWh 
C)  13 kWh 
D)  800 kWh 
A)  0.0080 kWh 
B)  0.80 kWh 
C)  13 kWh 
D)  800 kWh

Question 11

A 400-W computer (including its monitor) is turned on for 8.0 hours per day. If electricity costs 10¢ per kWh, how much does it cost to run the computer annually for a 365-day year?

Accepted Answer

A)  $120 
B)  $1200 
C)  $15 
D)  $150 
A)  $120 
B)  $1200 
C)  $15 
D)  $150

Question 12

What is the resistance of a 0.100-kW light bulb designed to be used in a 120-V circuit dc?

Accepted Answer

A)  12.0 Ω 
B)  144 Ω 
C)  1.2 Ω 
D)  0.83 Ω 
A)  12.0 Ω 
B)  144 Ω 
C)  1.2 Ω 
D)  0.83 Ω

Question 13

What potential difference is required across an 8.0-Ω resistor to cause 2.0 A to flow through it?

Accepted Answer

The answer of What potential difference is required across an...

Question 14

If the current flowing through a circuit of constant resistance is doubled, the power dissipated by that circuit will

Accepted Answer

A)  quadruple in magnitude. 
B)  double in magnitude. 
C)  decrease to one-half of what it was. 
D)  decrease to one-fourth of what it was. 
A)  quadruple in magnitude. 
B)  double in magnitude. 
C)  decrease to one-half of what it was. 
D)  decrease to one-fourth of what it was.

Question 15

What potential difference is required to cause 4.00 A to flow through a resistance of 330 Ω?

Accepted Answer

A)  12.1 V 
B)  82.5 V 
C)  334 V 
D)  1320 V 
A)  12.1 V 
B)  82.5 V 
C)  334 V 
D)  1320 V

Question 16

Which one of the following quantities is equivalent to 1 Ω?

Accepted Answer

A)  1 J/s 
B)  1 W/A 
C)  1 V ∙ A 
D)  1 V/A 
E)  1 A ∙ s 
A)  1 J/s 
B)  1 W/A 
C)  1 V ∙ A 
D)  1 V/A 
E)  1 A ∙ s

Question 17

For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?

Accepted Answer

A)  current 
B)  resistivity 
C)  1/(current) 
D)  power 
E)  1/(resistivity) 
A)  current 
B)  resistivity 
C)  1/(current) 
D)  power 
E)  1/(resistivity)

Question 18

A wire of resistivity ρ must be replaced in a circuit by a wire of the same material but four times as long. If, however, the total resistance is to remain as before, the diameter of the new wire must

Accepted Answer

A)  be the same as the original diameter. 
B)  be one-half the original diameter. 
C)  be one-fourth the original diameter. 
D)  be two times the original diameter. 
E)  be four times the original diameter. 
A)  be the same as the original diameter. 
B)  be one-half the original diameter. 
C)  be one-fourth the original diameter. 
D)  be two times the original diameter. 
E)  be four times the original diameter.

Question 19

What current is flowing in a resistor if 4.0 × 1016 electrons pass a point in the resistor in 0.50 s? (e = 1.60 × 10-19 C)

Accepted Answer

A)  0.013 A 
B)  0.31 A 
C)  6.3 A 
D)  78 A 
A)  0.013 A 
B)  0.31 A 
C)  6.3 A 
D)  78 A

Question 20

A 6.0-V battery that can store $500.0 \mathrm {~J}$ of energy is connected to a resistor. How much charge must flow between the battery's terminals to completely drain the battery if it is fully charged? Assume that the voltage of the battery remains the same until it is totally drained.

Accepted Answer

A)  83 C 
B)  0.010 C 
C)  3000 C 
D)  0.07 C 
A)  83 C 
B)  0.010 C 
C)  3000 C 
D)  0.07 C

Exam 22: Current and Resistance

What is the voltage drop across a 5.0-Ω resistor if the current through it is 5.0 A?

A 200-Ω resistor is rated at 1/4 W. What is the maximum voltage that can safely be connected across it?

A 100-W driveway light bulb is on 10 hours per day. If the power company charges 10¢ for each kilowatt-hour of electricity used, estimate the yearly cost to operate the bulb if it is used every day for a 365-day year.

The length of a certain wire is doubled and at the same time its radius is reduced by a factor of 2. What is the new resistance of this wire?

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? (e = 1.60 × 10-19 C)

When a 14.0-A current flows through an 8.00-Ω device for 24.0 hours, how much does this cost if energy costs $0.0900 per kW ∙ h?

A battery is rated such that it provides 1.0 mW1.0 \mathrm {~mW}1.0 mW of power at 9.0 V9.0 \mathrm {~V}9.0 V when fully charged. How much current can it deliver?

An instrument is rated at 250 W if it is connected across a 120-V dc power supply. (a) What current does it draw under normal operation? (b) What is its resistance? (c) How many kilowatt-hours does it use in a day if it is left on all the time?

How much energy does a 100-W light bulb use in 8.0 hours?

A 400-W computer (including its monitor) is turned on for 8.0 hours per day. If electricity costs 10¢ per kWh, how much does it cost to run the computer annually for a 365-day year?

What is the resistance of a 0.100-kW light bulb designed to be used in a 120-V circuit dc?

What potential difference is required across an 8.0-Ω resistor to cause 2.0 A to flow through it?

If the current flowing through a circuit of constant resistance is doubled, the power dissipated by that circuit will

What potential difference is required to cause 4.00 A to flow through a resistance of 330 Ω?

Which one of the following quantities is equivalent to 1 Ω?

For the graph shown in the figure, what physical quantity does the slope of the graph represent for ohmic material?

A wire of resistivity ρ must be replaced in a circuit by a wire of the same material but four times as long. If, however, the total resistance is to remain as before, the diameter of the new wire must

What current is flowing in a resistor if 4.0 × 1016 electrons pass a point in the resistor in 0.50 s? (e = 1.60 × 10-19 C)

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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? (e = 1.60 × 10^-19C)

A battery is rated such that it provides $1.0 \mathrm {~mW}$ of power at $9.0 \mathrm {~V}$ when fully charged. How much current can it deliver?

What current is flowing in a resistor if 4.0 × 10¹⁶ electrons pass a point in the resistor in 0.50 s? (e = 1.60 × 10^-19C)