Question 1

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 2

The figure shows a graph of the resistance of a wire as a function of its length. What physical quantities does the slope of this graph represent?

Accepted Answer

A)  the cross-sectional area of the wire 
B)  the resistivity of the material of which the wire is made 
C)  the product of the resistivity and the cross-sectional area of the wire 
D)  the resistivity of the material divided by the cross-sectional area of the wire 
E)  the reciprocal of the resistivity of the material 
A)  the cross-sectional area of the wire 
B)  the resistivity of the material of which the wire is made 
C)  the product of the resistivity and the cross-sectional area of the wire 
D)  the resistivity of the material divided by the cross-sectional area of the wire 
E)  the reciprocal of the resistivity of the material

Question 3

A battery is rated at 12 V and 160 A-h. How much energy does this battery store?

Accepted Answer

A)  1.9 kJ 
B)  6.0 kJ 
C)  1.9 MJ 
D)  6.9 MJ 
A)  1.9 kJ 
B)  6.0 kJ 
C)  1.9 MJ 
D)  6.9 MJ

Question 4

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

Accepted Answer

A)  1 V/A 
B)  1 Ω ∙ m 
C)  1 V ∙ A 
D)  1 V/Ω 
E)  1 A ∙ s 
A)  1 V/A 
B)  1 Ω ∙ m 
C)  1 V ∙ A 
D)  1 V/Ω 
E)  1 A ∙ s

Question 5

A light bulb operating at a dc voltage of 120 V has a resistance of 200 Ω. How much power is dissipated in this bulb?

Accepted Answer

A)  100 W 
B)  60 W 
C)  72 W 
D)  14 mW 
E)  7.2 W 
A)  100 W 
B)  60 W 
C)  72 W 
D)  14 mW 
E)  7.2 W

Question 6

A light bulb operating at a dc voltage of 120 V has a power rating of 60 W. How much current is flowing through this bulb?

Accepted Answer

A)  1.5 A 
B)  2.5 A 
C)  0.50 A 
D)  2.0 A 
E)  1.0 A 
A)  1.5 A 
B)  2.5 A 
C)  0.50 A 
D)  2.0 A 
E)  1.0 A

Question 7

If a quantity you calculated has units of Ω ∙ m what is that quantity?

Accepted Answer

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

Question 8

What is the resistance of a cylindrical metal rod 1.0 cm in diameter and 45 m long, if the resistivity of the metal is 1.4 × 10-8 Ω ∙ m?

Accepted Answer

A)  0.0063 Ω 
B)  0.0080 Ω 
C)  0.80 Ω 
D)  6.3 Ω 
A)  0.0063 Ω 
B)  0.0080 Ω 
C)  0.80 Ω 
D)  6.3 Ω

Question 9

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 10

A 12-V battery is connected across a 100-Ω resistor. How many electrons flow through the wire in 1.0 min? (e = 1.60 × 10-19 C)

Accepted Answer

A)  1.5 × 1019 
B)  2.5 × 1019 
C)  3.5 × 1019 
D)  4.5 × 1019 
A)  1.5 × 1019 
B)  2.5 × 1019 
C)  3.5 × 1019 
D)  4.5 × 1019

Question 11

A 4000-Ω resistor is connected across a 220-V power source. What current will flow through the resistor?

Accepted Answer

A)  0.055 A 
B)  1.8 A 
C)  5.5 A 
D)  18 A 
A)  0.055 A 
B)  1.8 A 
C)  5.5 A 
D)  18 A

Question 12

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

Accepted Answer

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

Question 13

If the power rating of a 400-Ω resistor is 0.80 W, what is the maximum current it can safely draw?

Accepted Answer

A)  45 mA 
B)  18 mA 
C)  4.4 mA 
D)  2.0 mA 
E)  320 mA 
A)  45 mA 
B)  18 mA 
C)  4.4 mA 
D)  2.0 mA 
E)  320 mA

Question 14

The power rating of a 400-Ω resistor is 0.800 W.
(a) What is the maximum safe voltage across this resistor?
(b) What is the maximum current the resistor can safely draw?

Accepted Answer

(a) 17.9 V

Question 15

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.

Question 16

If a quantity you calculated has units of $\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 3 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } }$ 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 17

A current of 5.0 A flows through an electrical device for 10 seconds. How many electrons flow through this device during this time? (e = 1.60 × 10-19 C)

Accepted Answer

A)  0.20 
B)  20 
C)  2.0 
D)  3.1 x $10^{20}$ 
E)  31 x $10^{20}$ 
A)  0.20 
B)  20 
C)  2.0 
D)  3.1 x $10^{20}$ 
E)  31 x $10^{20}$

Question 18

If a quantity you calculated has units of A ∙ s, what is that quantity?

Accepted Answer

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

Question 19

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 20

Copper wire #1 has a length L and a radius b. Copper wire #2 has a length 2L and a radius 2b. Which statement about the resistance across the ends of the wires is true?

Accepted Answer

A)  The resistance of wire #1 is twice as high as that of wire #2. 
B)  The resistance of wire #1 is equal to that of wire #2. 
C)  The resistance of wire #1 is half that of wire #2. 
D)  The resistance of wire #1 is four times higher than that of wire #2. 
A)  The resistance of wire #1 is twice as high as that of wire #2. 
B)  The resistance of wire #1 is equal to that of wire #2. 
C)  The resistance of wire #1 is half that of wire #2. 
D)  The resistance of wire #1 is four times higher than that of wire #2.

Exam 22: Current and Resistance

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

The figure shows a graph of the resistance of a wire as a function of its length. What physical quantities does the slope of this graph represent?

A battery is rated at 12 V and 160 A-h. How much energy does this battery store?

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

A light bulb operating at a dc voltage of 120 V has a resistance of 200 Ω. How much power is dissipated in this bulb?

A light bulb operating at a dc voltage of 120 V has a power rating of 60 W. How much current is flowing through this bulb?

If a quantity you calculated has units of Ω ∙ m what is that quantity?

What is the resistance of a cylindrical metal rod 1.0 cm in diameter and 45 m long, if the resistivity of the metal is 1.4 × 10-8 Ω ∙ m?

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?

A 12-V battery is connected across a 100-Ω resistor. How many electrons flow through the wire in 1.0 min? (e = 1.60 × 10-19 C)

A 4000-Ω resistor is connected across a 220-V power source. What current will flow through the resistor?

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

If the power rating of a 400-Ω resistor is 0.80 W, what is the maximum current it can safely draw?

The power rating of a 400-Ω resistor is 0.800 W. (a) What is the maximum safe voltage across this resistor? (b) What is the maximum current the resistor can safely draw?

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?

If a quantity you calculated has units of kg⋅m3 s⋅C2\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 3 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } } s⋅C2kg⋅m3​ what is that quantity?

A current of 5.0 A flows through an electrical device for 10 seconds. How many electrons flow through this device during this time? (e = 1.60 × 10-19 C)

If a quantity you calculated has units of A ∙ s, what is that quantity?

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?

Copper wire #1 has a length L and a radius b. Copper wire #2 has a length 2L and a radius 2b. Which statement about the resistance across the ends of the wires is true?

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What is the resistance of a cylindrical metal rod 1.0 cm in diameter and 45 m long, if the resistivity of the metal is 1.4 × 10^-8 Ω ∙ m?

A 12-V battery is connected across a 100-Ω resistor. How many electrons flow through the wire in 1.0 min? (e = 1.60 × 10^-¹⁹ C)

If a quantity you calculated has units of $\frac { \mathrm { kg } \cdot \mathrm { m } ^ { 3 } } { \mathrm {~s} \cdot \mathrm { C } ^ { 2 } }$ what is that quantity?

A current of 5.0 A flows through an electrical device for 10 seconds. How many electrons flow through this device during this time? (e = 1.60 × 10^-19C)