Question 1

A 1.56-V battery has an internal resistance of 0.120 Ω. What is the maximum current that can be drawn from this battery?

Accepted Answer

A)  infinite (or at least 1000s of amps) 
B)  1.56 A 
C)  0.190 A 
D)  13.0 A 
E)  7.50 A 
A)  infinite (or at least 1000s of amps) 
B)  1.56 A 
C)  0.190 A 
D)  13.0 A 
E)  7.50 A

Question 2

In the diagram, each resistor is 3 ohms, and the battery is 9 volts. What is the current through the middle resistor?

Accepted Answer

A)  3 A to the right 
B)  3 A to the left 
C)  9 A to the right 
D)  9 A to the left 
E)  1 A to the left 
A)  3 A to the right 
B)  3 A to the left 
C)  9 A to the right 
D)  9 A to the left 
E)  1 A to the left

Question 3

A carbon resistor is made of a cylinder of carbon, of length 1.5 cm. If the resistivity of carbon is 3.5 × 10−5 Ω·m, and a potential difference of 0.15 V causes a current of 12 A to flow through the resistor, what is the radius of the cylinder?

Accepted Answer

A)  6.5 mm 
B)  12 mm 
C)  3.7 mm 
D)  1.2 mm 
A)  6.5 mm 
B)  12 mm 
C)  3.7 mm 
D)  1.2 mm

Question 4

Four 12 Ω resistors are connected together. What is the least resistance that can be attained with these resistors by connecting them in various ways?

Accepted Answer

A)  12 Ω 
B)  6.0 Ω 
C)  3.0 Ω 
D)  2.0 Ω 
E)  1.0 Ω 
A)  12 Ω 
B)  6.0 Ω 
C)  3.0 Ω 
D)  2.0 Ω 
E)  1.0 Ω

Question 5

By how much does the current fall after the switch is closed in a series RC circuit when three time constants have elapsed?

Accepted Answer

A)  5.0% 
B)  38% 
C)  62% 
D)  95% 
E)  100% since after 2 time constants the current is 0 
A)  5.0% 
B)  38% 
C)  62% 
D)  95% 
E)  100% since after 2 time constants the current is 0

Question 6

If R1 = 6 Ω, R2 = 8 Ω, R3 = 2 Ω, ε1 = 4 V, and ε2 = 14 V, what is the current in R2?

Accepted Answer

A)  1 A up 
B)  1 A down 
C)  2.5 A up 
D)  2.5 A down 
E)  5 A down 
A)  1 A up 
B)  1 A down 
C)  2.5 A up 
D)  2.5 A down 
E)  5 A down

Question 7

The watt, W, is equivalent to which of the following?

Accepted Answer

A)  A·V 
B)  C·J 
C)  C/J 
D)  A/V 
E)  V2/A 
A)  A·V 
B)  C·J 
C)  C/J 
D)  A/V 
E)  V2/A

Question 8

Capacitors of values 1.0 F, 2.0 F, 3.0 F, and 6.0 F are connected in series across a 12 V power supply. Which capacitor has the greatest potential difference across it?

Accepted Answer

A)  the 1.0 F capacitor 
B)  the 2.0 F capacitor 
C)  the 3.0 F capacitor 
D)  the 6.0 F capacitor 
E)  they all are equal 
A)  the 1.0 F capacitor 
B)  the 2.0 F capacitor 
C)  the 3.0 F capacitor 
D)  the 6.0 F capacitor 
E)  they all are equal

Question 9

In an RC circuit with an initially uncharged capacitor, the time constant is the time that is required for the current through the resistor to reach what percentage of its initial value?

Accepted Answer

A)  63% 
B)  90% 
C)  37% 
D)  100% 
E)  50% 
A)  63% 
B)  90% 
C)  37% 
D)  100% 
E)  50%

Question 10

When current flows through a wire

Accepted Answer

A)  electrons are moving in the direction of the current. 
B)  electrons are moving opposite the direction of the current. 
C)  protons are moving in the direction of the current. 
D)  protons are moving opposite the direction of the current. 
E)  both protons and electrons are moving in the direction of the current. 
A)  electrons are moving in the direction of the current. 
B)  electrons are moving opposite the direction of the current. 
C)  protons are moving in the direction of the current. 
D)  protons are moving opposite the direction of the current. 
E)  both protons and electrons are moving in the direction of the current.

Question 11

The resistance of a wire increases by 3.9% when the temperature of the wire is raised 100°C. What is the temperature coefficient of resistivity of the wire material?

Accepted Answer

A)  3.9°C−1 
B)  0.39°C−1 
C)  0.039°C−1 
D)  0.0039°C−1 
E)  0.00039°C−1 
A)  3.9°C−1 
B)  0.39°C−1 
C)  0.039°C−1 
D)  0.0039°C−1 
E)  0.00039°C−1

Question 12

In a three-pronged plug, the purpose of the third prong is to

Accepted Answer

A)  provide a short circuit to ground. 
B)  prevent excessive power use by inefficient appliances. 
C)  create a stronger connection to the outlet when plugged in. 
D)  provide a path to ground in the event of a short circuit to the case of an appliance. 
A)  provide a short circuit to ground. 
B)  prevent excessive power use by inefficient appliances. 
C)  create a stronger connection to the outlet when plugged in. 
D)  provide a path to ground in the event of a short circuit to the case of an appliance.

Question 13

A 2.50 A current is carried by a copper wire of radius 1.0 mm. If the density of conduction electrons is 8.0 × 1028 m−3, what is the drift velocity of the conduction electrons?

Accepted Answer

A)  3.0 × 108 m/s 
B)  3.2 × 10−4 m/s 
C)  1.6 × 10−5 m/s 
D)  6.2 × 10−4 m/s 
E)  6.2 × 10−5 m/s 
A)  3.0 × 108 m/s 
B)  3.2 × 10−4 m/s 
C)  1.6 × 10−5 m/s 
D)  6.2 × 10−4 m/s 
E)  6.2 × 10−5 m/s

Question 14

In a series circuit consisting of a 12.0 V source of emf, a 2.00 mF capacitor, a 1.00 kΩ resistor and a switch, what is the voltage across the capacitor at a time of one time constant t after the switch is closed?

Accepted Answer

A)  0.632 V 
B)  6.32 V 
C)  7.59 V 
D)  8.65 V 
A)  0.632 V 
B)  6.32 V 
C)  7.59 V 
D)  8.65 V

Question 15

A 6.0 Ω resistor and a 3.0 Ω resistor are connected in parallel to a 1.5 V battery of negligible internal resistance. What is the current in the 3.0 Ω resistor?

Accepted Answer

A)  2.0 A 
B)  0.50 A 
C)  0.25 A 
D)  0.17 A 
E)  0.75 A 
A)  2.0 A 
B)  0.50 A 
C)  0.25 A 
D)  0.17 A 
E)  0.75 A

Question 16

Two capacitors of values 6.00 mF and 9.00 mF are connected in series to a 30.0 V power supply. What is the resulting charge on the 6.00 mF capacitor?

Accepted Answer

A)  180 mC 
B)  270 mC 
C)  90.0 mC 
D)  108 mC 
E)  200 mC 
A)  180 mC 
B)  270 mC 
C)  90.0 mC 
D)  108 mC 
E)  200 mC

Question 17

Three wires are connected at a junction. One of the wires carries a current of 4 A into the junction, while another carries 5 A into the junction. What is the current in the third wire?

Accepted Answer

A)  4 A away from the junction 
B)  9 A away from the junction 
C)  4 A into the junction 
D)  9 A into the junction 
E)  1 A away from the junction 
A)  4 A away from the junction 
B)  9 A away from the junction 
C)  4 A into the junction 
D)  9 A into the junction 
E)  1 A away from the junction

Question 18

Four 12 Ω resistors are connected together. What is the maximum resistance that can be attained with these resistors by connecting them in various ways?

Accepted Answer

A)  12 Ω 
B)  24 Ω 
C)  36 Ω 
D)  48 Ω 
E)  44 Ω 
A)  12 Ω 
B)  24 Ω 
C)  36 Ω 
D)  48 Ω 
E)  44 Ω

Question 19

A 12.0 V battery is connected across a 4.00-Ω resistor. If the current through the resistor is 2.80 A, what is the internal resistance of the battery?

Accepted Answer

A)  0.200 Ω 
B)  0.286 Ω 
C)  4.29 Ω 
D)  3.71 Ω 
E)  0.800 Ω 
A)  0.200 Ω 
B)  0.286 Ω 
C)  4.29 Ω 
D)  3.71 Ω 
E)  0.800 Ω

Question 20

One hundred meters of 2.00 mm diameter wire has a resistance of 0.532 Ω. What is the resistivity of the material from which the wire is made?

Accepted Answer

A)  1.59 × 10-8 Ω·m 
B)  1.67 × 10-8 Ω·m 
C)  2.35 × 10-8 Ω·m 
D)  2.65 × 10-8 Ω·m 
E)  5.40 × 10-8 Ω·m 
A)  1.59 × 10-8 Ω·m 
B)  1.67 × 10-8 Ω·m 
C)  2.35 × 10-8 Ω·m 
D)  2.65 × 10-8 Ω·m 
E)  5.40 × 10-8 Ω·m

Exam 18: Electric Current and Circuits

A 1.56-V battery has an internal resistance of 0.120 Ω. What is the maximum current that can be drawn from this battery?

In the diagram, each resistor is 3 ohms, and the battery is 9 volts. What is the current through the middle resistor?

A carbon resistor is made of a cylinder of carbon, of length 1.5 cm. If the resistivity of carbon is 3.5 × 10−5 Ω·m, and a potential difference of 0.15 V causes a current of 12 A to flow through the resistor, what is the radius of the cylinder?

Four 12 Ω resistors are connected together. What is the least resistance that can be attained with these resistors by connecting them in various ways?

By how much does the current fall after the switch is closed in a series RC circuit when three time constants have elapsed?

If R1 = 6 Ω, R2 = 8 Ω, R3 = 2 Ω, ε1 = 4 V, and ε2 = 14 V, what is the current in R2?

The watt, W, is equivalent to which of the following?

Capacitors of values 1.0 F, 2.0 F, 3.0 F, and 6.0 F are connected in series across a 12 V power supply. Which capacitor has the greatest potential difference across it?

In an RC circuit with an initially uncharged capacitor, the time constant is the time that is required for the current through the resistor to reach what percentage of its initial value?

When current flows through a wire

The resistance of a wire increases by 3.9% when the temperature of the wire is raised 100°C. What is the temperature coefficient of resistivity of the wire material?

In a three-pronged plug, the purpose of the third prong is to

A 2.50 A current is carried by a copper wire of radius 1.0 mm. If the density of conduction electrons is 8.0 × 1028 m−3, what is the drift velocity of the conduction electrons?

In a series circuit consisting of a 12.0 V source of emf, a 2.00 mF capacitor, a 1.00 kΩ resistor and a switch, what is the voltage across the capacitor at a time of one time constant t after the switch is closed?

A 6.0 Ω resistor and a 3.0 Ω resistor are connected in parallel to a 1.5 V battery of negligible internal resistance. What is the current in the 3.0 Ω resistor?

Two capacitors of values 6.00 mF and 9.00 mF are connected in series to a 30.0 V power supply. What is the resulting charge on the 6.00 mF capacitor?

Three wires are connected at a junction. One of the wires carries a current of 4 A into the junction, while another carries 5 A into the junction. What is the current in the third wire?

Four 12 Ω resistors are connected together. What is the maximum resistance that can be attained with these resistors by connecting them in various ways?

A 12.0 V battery is connected across a 4.00-Ω resistor. If the current through the resistor is 2.80 A, what is the internal resistance of the battery?

One hundred meters of 2.00 mm diameter wire has a resistance of 0.532 Ω. What is the resistivity of the material from which the wire is made?

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Filters

A carbon resistor is made of a cylinder of carbon, of length 1.5 cm. If the resistivity of carbon is 3.5 × 10⁻⁵ Ω·m, and a potential difference of 0.15 V causes a current of 12 A to flow through the resistor, what is the radius of the cylinder?

If R₁ = 6 Ω, R₂ = 8 Ω, R₃ = 2 Ω, ε₁ = 4 V, and ε₂ = 14 V, what is the current in R₂?

A 2.50 A current is carried by a copper wire of radius 1.0 mm. If the density of conduction electrons is 8.0 × 10²⁸ m⁻³, what is the drift velocity of the conduction electrons?