Question 1

If the resistance in a constant voltage circuit is doubled, the power dissipated by that circuit will

Accepted Answer

A) increase by a factor of two. 
B) increase by a factor of four. 
C) decrease to one-half its original value. 
D) decrease to one-fourth its original value. 
A) increase by a factor of two. 
B) increase by a factor of four. 
C) decrease to one-half its original value. 
D) decrease to one-fourth its original value. C

Question 2

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 A

Question 3

Consider two copper wires with circular cross-sections and equal lengths. One wire has 3 times the diameter of the other. How do the resistances of these two wires compare?

Accepted Answer

A) The thicker wire has 1/3 the resistance of the thinner wire. 
B) The thicker wire has 1/9 the resistance of the thinner wire. 
C) The thicker wire has 3 times the resistance of the thinner wire. 
D) The thicker wire has 9 times the resistance of the thinner wire. 
E) The thicker wire has $\sqrt { 3 }$ times the resistance of the thinner wire. 
A) The thicker wire has 1/3 the resistance of the thinner wire. 
B) The thicker wire has 1/9 the resistance of the thinner wire. 
C) The thicker wire has 3 times the resistance of the thinner wire. 
D) The thicker wire has 9 times the resistance of the thinner wire. 
E) The thicker wire has $\sqrt { 3 }$ times the resistance of the thinner wire. B

Question 4

The resistance of a 100-cm wire of cross sectional area 2 × $10 ^ { - 6 }$ $m ^ { 2 }$ is 400 ?. What is the resistivity of the material from which this wire is made?

Accepted Answer

A) 0.80 × $10 ^ { - 4 }$ ? ? m 
B) 8.0 × $10 ^ { - 4 }$ ? ? m 
C) 0.80 × $10 ^ { - 5 }$ ? ? m 
D) 0.80 × $10 ^ { - 6 }$ ? ? m 
E) 8.0 × $10 ^ { - 6 }$ ?v 
A) 0.80 × $10 ^ { - 4 }$ ? ? m 
B) 8.0 × $10 ^ { - 4 }$ ? ? m 
C) 0.80 × $10 ^ { - 5 }$ ? ? m 
D) 0.80 × $10 ^ { - 6 }$ ? ? m 
E) 8.0 × $10 ^ { - 6 }$ ?v

Question 5

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 6

Calculate the current through a 10.0-m long 22-gauge nichrome wire with a radius of 0.321 mm if it is connected across a 12.0-V battery. The resistivity of the nichrome is 1.00 × 10-6 Ω ∙ m.

Accepted Answer

A) 30.9 A 
B) 61.8 A 
C) 0.388 A 
D) 0.776 A 
A) 30.9 A 
B) 61.8 A 
C) 0.388 A 
D) 0.776 A

Question 7

A 200-W light bulb is connected across a 110-V dc power supply. What current will flow through this bulb?

Accepted Answer

A) 0.90 A 
B) 0.36 A 
C) 0 A 
D) 0.60 A 
E) 1.8 A 
A) 0.90 A 
B) 0.36 A 
C) 0 A 
D) 0.60 A 
E) 1.8 A

Question 8

A kilowatt-hour is equivalent to

Accepted Answer

A) 1000 W. 
B) 3600 J. 
C) 3,600,000 J/s. 
D) 3,600,000 J. 
E) 3600 J/s 
A) 1000 W. 
B) 3600 J. 
C) 3,600,000 J/s. 
D) 3,600,000 J. 
E) 3600 J/s

Question 9

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 10

The length of a certain wire is kept same while its radius is doubled. What is the new resistance of this wire?

Accepted Answer

A) It is increased by a factor of 2. 
B) It is increased by a factor of 4. 
C) It is reduced by a factor of 2. 
D) It is reduced by a factor of 4. 
E) It is reduced by a factor of 8. 
A) It is increased by a factor of 2. 
B) It is increased by a factor of 4. 
C) It is reduced by a factor of 2. 
D) It is reduced by a factor of 4. 
E) It is reduced by a factor of 8.

Question 11

When 5.00 A is flowing through an 10.0-Ω device, how much power is being dissipated in the device?

Accepted Answer

A) 50.0 W 
B) 250 W 
C) 500 W 
D) 2.50 kW 
A) 50.0 W 
B) 250 W 
C) 500 W 
D) 2.50 kW

Question 12

A 10-A current flows through a wire for 2.0 min. (e = 1.60 × 10-19 C)
(a)How much charge has passed through this wire?
(b)How many electrons have passed any point in the wire?

Accepted Answer

(a)1200 C

Question 13

A 1.0-m length of nichrome wire has a radius of 0.50 mm and a resistivity of 1.0 × 10-6 Ω ∙ m. When this wire carries a current of 0.50 A, what is the voltage across its ends?

Accepted Answer

A) 0.0030 V 
B) 0.32 V 
C) 0.64 V 
D) 1.6 V 
A) 0.0030 V 
B) 0.32 V 
C) 0.64 V 
D) 1.6 V

Question 14

A 1.0-mm diameter extension cord is made of metal having a resistivity of 1.68 × 10-8 Ω ∙ m. When it carries a current of 15 A, what is the potential difference between two points in the cord that are 100 m apart?

Accepted Answer

A) 12 V 
B) 23 V 
C) 32 V 
D) 41 V 
A) 12 V 
B) 23 V 
C) 32 V 
D) 41 V

Question 15

A light bulb operating at 110 V draws 1.40 A of current. What is its resistance?

Accepted Answer

A) 12.7 Ω 
B) 78.6 Ω 
C) 109 Ω 
D) 154 Ω 
A) 12.7 Ω 
B) 78.6 Ω 
C) 109 Ω 
D) 154 Ω

Question 16

The graph shown in the figure shows the results of measurements of the dc current through a circuit device for various potential differences across it. Assume that all the numbers shown are accurate to two significant figures. What is the resistance of this device?

Accepted Answer

The answer of The graph shown in the figure shows...

Question 17

For the graph shown in the figure, what physical quantity does the slope of the graph represent for a dc circuit?

Accepted Answer

A) resistivity 
B) resistance 
C) energy 
D) current 
E) capacitance 
A) resistivity 
B) resistance 
C) energy 
D) current 
E) capacitance

Question 18

Consider two copper wires of equal cross-sectional area. One wire has 3 times the length of the other. How do the resistivities of these two wires compare?

Accepted Answer

A) Both wires have the same resistivity. 
B) The longer wire has 3 times the resistivity of the shorter wire. 
C) The longer wire has 9 times times the resistivity of the shorter wire. 
D) The longer wire has 27 times times the resistivity of the shorter wire. 
A) Both wires have the same resistivity. 
B) The longer wire has 3 times the resistivity of the shorter wire. 
C) The longer wire has 9 times times the resistivity of the shorter wire. 
D) The longer wire has 27 times times the resistivity of the shorter wire.

Question 19

What is the resistance of 1.0 m of a solid cylindrical metal cable having a diameter of 0.40 inches and a resistivity of 1.68 × 10-8 Ω ∙ m?

Accepted Answer

A) 0.00012 Ω 
B) 0.00021 Ω 
C) 0.0012 Ω 
D) 0.0021 Ω 
A) 0.00012 Ω 
B) 0.00021 Ω 
C) 0.0012 Ω 
D) 0.0021 Ω

Question 20

When current is flowing in an ordinary metal wire, the magnitude of the average velocity of the electrons is closest to

Accepted Answer

A) 10 m/s. 
B) the speed of light. 
C) 1 mm/s. 
D) 1 km/s. 
E) 1 m/s. 
A) 10 m/s. 
B) the speed of light. 
C) 1 mm/s. 
D) 1 km/s. 
E) 1 m/s.

Exam 22: Current and Resistance

If the resistance in a constant voltage circuit is doubled, the power dissipated by that circuit will

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?

Consider two copper wires with circular cross-sections and equal lengths. One wire has 3 times the diameter of the other. How do the resistances of these two wires compare?

The resistance of a 100-cm wire of cross sectional area 2 × 10−610 ^ { - 6 }10−6 m2m ^ { 2 }m2 is 400 ?. What is the resistivity of the material from which this wire is made?

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?

Calculate the current through a 10.0-m long 22-gauge nichrome wire with a radius of 0.321 mm if it is connected across a 12.0-V battery. The resistivity of the nichrome is 1.00 × 10-6 Ω ∙ m.

A 200-W light bulb is connected across a 110-V dc power supply. What current will flow through this bulb?

A kilowatt-hour is equivalent to

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

The length of a certain wire is kept same while its radius is doubled. What is the new resistance of this wire?

When 5.00 A is flowing through an 10.0-Ω device, how much power is being dissipated in the device?

A 10-A current flows through a wire for 2.0 min. (e = 1.60 × 10-19 C) (a)How much charge has passed through this wire? (b)How many electrons have passed any point in the wire?

A 1.0-m length of nichrome wire has a radius of 0.50 mm and a resistivity of 1.0 × 10-6 Ω ∙ m. When this wire carries a current of 0.50 A, what is the voltage across its ends?

A 1.0-mm diameter extension cord is made of metal having a resistivity of 1.68 × 10-8 Ω ∙ m. When it carries a current of 15 A, what is the potential difference between two points in the cord that are 100 m apart?

A light bulb operating at 110 V draws 1.40 A of current. What is its resistance?

The graph shown in the figure shows the results of measurements of the dc current through a circuit device for various potential differences across it. Assume that all the numbers shown are accurate to two significant figures. What is the resistance of this device?

For the graph shown in the figure, what physical quantity does the slope of the graph represent for a dc circuit?

Consider two copper wires of equal cross-sectional area. One wire has 3 times the length of the other. How do the resistivities of these two wires compare?

What is the resistance of 1.0 m of a solid cylindrical metal cable having a diameter of 0.40 inches and a resistivity of 1.68 × 10-8 Ω ∙ m?

When current is flowing in an ordinary metal wire, the magnitude of the average velocity of the electrons is closest to

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The resistance of a 100-cm wire of cross sectional area 2 × $10 ^ { - 6 }$ $m ^ { 2 }$ is 400 ?. What is the resistivity of the material from which this wire is made?

Calculate the current through a 10.0-m long 22-gauge nichrome wire with a radius of 0.321 mm if it is connected across a 12.0-V battery. The resistivity of the nichrome is 1.00 × 10^-6 Ω ∙ m.

A 10-A current flows through a wire for 2.0 min. (e = 1.60 × 10^-19C) (a)How much charge has passed through this wire? (b)How many electrons have passed any point in the wire?

A 1.0-m length of nichrome wire has a radius of 0.50 mm and a resistivity of 1.0 × 10^-6 Ω ∙ m. When this wire carries a current of 0.50 A, what is the voltage across its ends?

A 1.0-mm diameter extension cord is made of metal having a resistivity of 1.68 × 10^-8 Ω ∙ m. When it carries a current of 15 A, what is the potential difference between two points in the cord that are 100 m apart?

What is the resistance of 1.0 m of a solid cylindrical metal cable having a diameter of 0.40 inches and a resistivity of 1.68 × 10^-8 Ω ∙ m?