Question 1

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 E

Question 2

What current is flowing in a wire if 0.67 C of charge pass a point in the wire in 0.30 s?

Accepted Answer

A)  2.2 A 
B)  0.67 A 
C)  0.30 A 
D)  0.20 A 
A)  2.2 A 
B)  0.67 A 
C)  0.30 A 
D)  0.20 A A

Question 3

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

Accepted Answer

A)  1/(resistance) 
B)  resistance 
C)  potential 
D)  (potential)2 
E)  1/(potential) 
A)  1/(resistance) 
B)  resistance 
C)  potential 
D)  (potential)2 
E)  1/(potential) E

Question 4

How much current will flow through a 40.0 -$
{ m }$ length of metal wire with a radius of $0.0 \mathrm {~mm}$ if it is connected to a power source supplying $16.0 \mathrm {~V} ?$ The resistivity of the metal is 1.68 × 10-8 Ω ∙ m.

Accepted Answer

A)  0 A 
B)  0 x 108 A 
C)  0 nA 
A)  0 A 
B)  0 x 108 A 
C)  0 nA

Question 5

The voltage drop across a metal bar is $5.0 \mathrm {~V}$ while a current of $10.0 \mathrm {~mA}$ flows through it. How much power does this bar dissipate?

Accepted Answer

A)  50 mW 
B)  500 μW 
C)  2.5 kW 
D)  0.50 kW 
A)  50 mW 
B)  500 μW 
C)  2.5 kW 
D)  0.50 kW

Question 6

A 9.0-V battery costs $1.49 and will run a portable CD player for 6.0 hours before running down and needing to be replaced. If this battery supplies a current of 25 mA to the player, what is the cost of the energy provided by the battery in dollars per kWh?

Accepted Answer

A)  $11/kWh 
B)  $110/kWh 
C)  $1100/kWh 
D)  $11,000/kWh 
A)  $11/kWh 
B)  $110/kWh 
C)  $1100/kWh 
D)  $11,000/kWh

Question 7

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

Accepted Answer

A)  be four times as large. 
B)  be two times as large. 
C)  decrease to one-half the original power. 
D)  decrease to one-fourth the original power. 
A)  be four times as large. 
B)  be two times as large. 
C)  decrease to one-half the original power. 
D)  decrease to one-fourth the original power.

Question 8

The figure shows conventional current passing through a resistor. The arrow shows the direction in which this conventional current is flowing. Which of the following statements are correct? (There could be more than one correct choice.)

Accepted Answer

A)  The charges are moving slower at point b than at point a. 
B)  The electric potential is lower at point b than at point a. 
C)  The electric potential is higher at point b than at point a. 
D)  The current at point b is the same as the current at point a. 
E)  The electric potential at point b is the same as it is at point a. 
A)  The charges are moving slower at point b than at point a. 
B)  The electric potential is lower at point b than at point a. 
C)  The electric potential is higher at point b than at point a. 
D)  The current at point b is the same as the current at point a. 
E)  The electric potential at point b is the same as it is at point a.

Question 9

If a quantity you calculated has units of $\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 2 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } }$ what is that quantity?

Accepted Answer

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

Question 10

A charge of 12 C passes through an electroplating apparatus in 2.0 min. What is the average current in the apparatus?

Accepted Answer

A)  0.10 A 
B)  0.60 A 
C)  1.0 A 
D)  6.0 A 
A)  0.10 A 
B)  0.60 A 
C)  1.0 A 
D)  6.0 A

Question 11

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 12

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

Accepted Answer

A)  0.80 × $10^{ - 4}$ Ω ∙ m 
B)  8.0 × $10 ^{- 4}$ Ω ∙ m 
C)  0.80 × $10 ^ { - 5 }$ Ω ∙ m 
D)  0.80 × $10^{ - 6}$ Ω ∙ m 
E)  8.0 × $10 ^{- 6}$ Ωv 
A)  0.80 × $10^{ - 4}$ Ω ∙ m 
B)  8.0 × $10 ^{- 4}$ Ω ∙ m 
C)  0.80 × $10 ^ { - 5 }$ Ω ∙ m 
D)  0.80 × $10^{ - 6}$ Ω ∙ m 
E)  8.0 × $10 ^{- 6}$ Ωv

Question 13

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

Accepted Answer

A)  It stays the same. 
B)  It is 2 times as large. 
C)  It is 4 times as large. 
D)  It is 1/2 as large. 
E)  It is 1/4 as large. 
A)  It stays the same. 
B)  It is 2 times as large. 
C)  It is 4 times as large. 
D)  It is 1/2 as large. 
E)  It is 1/4 as large.

Question 14

A toaster is rated at 800 W when operating at 120 V dc. What is the resistance of its heating element?

Accepted Answer

A)  16 Ω 
B)  18 Ω 
C)  6.7 Ω 
D)  0.15 Ω 
A)  16 Ω 
B)  18 Ω 
C)  6.7 Ω 
D)  0.15 Ω

Question 15

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 mass of silver is 108 g/mol. (e = 1.60 × 10-19 C, NA = 6.02 × 1023 atoms/mol)

Accepted Answer

A)  16 s 
B)  18 s 
C)  20 s 
D)  22 s 
A)  16 s 
B)  18 s 
C)  20 s 
D)  22 s

Question 16

The figure shows a graph of the power dissipated in a resistor as a function of the resistance. What quantity does the slope of this graph represent?

Accepted Answer

A)  the current in the resistor 
B)  the potential difference across the resistor 
C)  the reciprocal of the current in the resistor 
D)  the square of the current in the resistor 
E)  the resistivity of the resistor 
A)  the current in the resistor 
B)  the potential difference across the resistor 
C)  the reciprocal of the current in the resistor 
D)  the square of the current in the resistor 
E)  the resistivity of the resistor

Question 17

How much charge must pass by a point in a wire in 10 s for the current inb the wire to be 0.50 A?

Accepted Answer

A)  20 C 
B)  2.0 C 
C)  5.0 C 
D)  0.050 C 
A)  20 C 
B)  2.0 C 
C)  5.0 C 
D)  0.050 C

Question 18

A jeweler needs to electroplate gold, having an atomic mass of 196.97 g/mol, onto a bracelet. He knows that the charge carriers in the ionic solution are singly-ionized gold ions, Au+, and has calculated that he must deposit $0.20 \mathrm {~g}$ of gold to reach the necessary thickness. How much current does he need to plate the bracelet in 3.0 hours? (e = 1.60 × 10-19 C, NA = 6.02 × 1023 atoms/mol)

Accepted Answer

A)  9.1 mA 
B)  540 mA 
C)  33 A 
D)  1800 mA 
A)  9.1 mA 
B)  540 mA 
C)  33 A 
D)  1800 mA

Question 19

A metal bar is 20 cm long and has a rectangular cross-section measuring 1.0 cm × 2.0 cm. What is the voltage drop along its length when it carries a 4000-A current? The resistivity of the metal is 1.68 × 10-8 Ω ∙ m.

Accepted Answer

A)  0.67 V 
B)  0.34 V 
C)  0.067 V 
D)  0.034 V 
A)  0.67 V 
B)  0.34 V 
C)  0.067 V 
D)  0.034 V

Question 20

If the power rating of a 400-Ω resistor is 0.800 W, what is the maximum voltage that can safely be connected across the resistor?

Accepted Answer

A)  110 V 
B)  17.9 V 
C)  170 V 
D)  1.80 V 
A)  110 V 
B)  17.9 V 
C)  170 V 
D)  1.80 V

Exam 22: Current and Resistance

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

What current is flowing in a wire if 0.67 C of charge pass a point in the wire in 0.30 s?

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

How much current will flow through a 40.0 - m{ m }m length of metal wire with a radius of 0.0 mm0.0 \mathrm {~mm}0.0 mm if it is connected to a power source supplying 16.0 V?16.0 \mathrm {~V} ?16.0 V? The resistivity of the metal is 1.68 × 10-8 Ω ∙ m.

The voltage drop across a metal bar is 5.0 V5.0 \mathrm {~V}5.0 V while a current of 10.0 mA10.0 \mathrm {~mA}10.0 mA flows through it. How much power does this bar dissipate?

A 9.0-V battery costs $1.49 and will run a portable CD player for 6.0 hours before running down and needing to be replaced. If this battery supplies a current of 25 mA to the player, what is the cost of the energy provided by the battery in dollars per kWh?

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

The figure shows conventional current passing through a resistor. The arrow shows the direction in which this conventional current is flowing. Which of the following statements are correct? (There could be more than one correct choice.)

If a quantity you calculated has units of kg⋅m2 s⋅C2\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 2 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } } s⋅C2kg⋅m2​ what is that quantity?

A charge of 12 C passes through an electroplating apparatus in 2.0 min. What is the average current in the apparatus?

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?

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

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

A toaster is rated at 800 W when operating at 120 V dc. What is the resistance of its heating element?

The figure shows a graph of the power dissipated in a resistor as a function of the resistance. What quantity does the slope of this graph represent?

How much charge must pass by a point in a wire in 10 s for the current inb the wire to be 0.50 A?

A metal bar is 20 cm long and has a rectangular cross-section measuring 1.0 cm × 2.0 cm. What is the voltage drop along its length when it carries a 4000-A current? The resistivity of the metal is 1.68 × 10-8 Ω ∙ m.

If the power rating of a 400-Ω resistor is 0.800 W, what is the maximum voltage that can safely be connected across the resistor?

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How much current will flow through a 40.0 - ${ m }$ length of metal wire with a radius of $0.0 \mathrm {~mm}$ if it is connected to a power source supplying $16.0 \mathrm {~V} ?$ The resistivity of the metal is 1.68 × 10^-8 Ω ∙ m.

The voltage drop across a metal bar is $5.0 \mathrm {~V}$ while a current of $10.0 \mathrm {~mA}$ flows through it. How much power does this bar dissipate?

If a quantity you calculated has units of $\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 2 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } }$ what is that quantity?

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?

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

A metal bar is 20 cm long and has a rectangular cross-section measuring 1.0 cm × 2.0 cm. What is the voltage drop along its length when it carries a 4000-A current? The resistivity of the metal is 1.68 × 10^-8 Ω ∙ m.