Question 1

A 100-W light bulb is connected to a 110-V source. What current flows through the lamp?

Accepted Answer

A)  1.1 A 
B)  2.2 A 
C)  3.3 A 
D)  4.4 A 
E)  0.91 A 
A)  1.1 A 
B)  2.2 A 
C)  3.3 A 
D)  4.4 A 
E)  0.91 A E

Question 2

The length of a certain wire is halved while the radius is doubled. What is the change in the resistance of this wire?

Accepted Answer

A)  It stays the same. 
B)  It is reduced by a factor of 2. 
C)  It is reduced by a factor of 4. 
D)  It is reduced by a factor of 8. 
E)  It is quadrupled. 
A)  It stays the same. 
B)  It is reduced by a factor of 2. 
C)  It is reduced by a factor of 4. 
D)  It is reduced by a factor of 8. 
E)  It is quadrupled. D

Question 3

FIGURE 21-1  
-Identify the junction nodes in the circuit shown in Figure 21-1.

Accepted Answer

A)  A and B 
B)  D and E 
C)  A and E 
D)  C and F 
E)  E and F 
A)  A and B 
B)  D and E 
C)  A and E 
D)  C and F 
E)  E and F D

Question 4

FIGURE 21-18  
-A 4.0 μF and a 6.0 μF capacitor are connected in series across an 8.0-V DC source. What is the charge on the 6.0 μF capacitor?

Accepted Answer

A)  2.0 μC 
B)  4.0 μC 
C)  12 μC 
D)  25 μC 
E)  19 μC 
A)  2.0 μC 
B)  4.0 μC 
C)  12 μC 
D)  25 μC 
E)  19 μC

Question 5

FIGURE 21-15  
-Four resistors of values 2.0 Ω, 4.0 Ω, 3.0 Ω, and 9.0 Ω are connected across a DC source with voltage V as shown in Figure 21-15. If the total current through this circuit is 2.0 A, what is the current through the 4-Ω resistor?

Accepted Answer

A)  1.0 A 
B)  2.0 A 
C)  3.0 A 
D)  1.3 A 
E)  2.4 A 
A)  1.0 A 
B)  2.0 A 
C)  3.0 A 
D)  1.3 A 
E)  2.4 A

Question 6

Four unequal resistors are connected in a series circuit. Which one of the following statements is correct about this circuit?

Accepted Answer

A)  The total resistance is equal to any one of the resistors. 
B)  The total resistance is equal to average of the four resistors. 
C)  The total resistance is less than the smallest resistor. 
D)  The total resistance is less than the largest resistor. 
E)  The total resistance is more than the largest resistor. 
A)  The total resistance is equal to any one of the resistors. 
B)  The total resistance is equal to average of the four resistors. 
C)  The total resistance is less than the smallest resistor. 
D)  The total resistance is less than the largest resistor. 
E)  The total resistance is more than the largest resistor.

Question 7

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

Accepted Answer

A)  remain unchanged. 
B)  be two times smaller. 
C)  be four times smaller. 
D)  be two times larger. 
E)  be four times larger. 
A)  remain unchanged. 
B)  be two times smaller. 
C)  be four times smaller. 
D)  be two times larger. 
E)  be four times larger.

Question 8

Four unequal resistors connected in series have same current but different voltages.

Accepted Answer

A) True 
 B)False

Question 9

Four resistors of 20 Ω, 40 Ω, 60 Ω, and 80 Ω are connected across a DC voltage source. If the current through this circuit is 0.5 A, what is the voltage applied to this circuit?

Accepted Answer

A)  20 V 
B)  40 V 
C)  60 V 
D)  80 V 
E)  100 V 
A)  20 V 
B)  40 V 
C)  60 V 
D)  80 V 
E)  100 V

Question 10

The power rating of a 400 Ω resistor is 0.25 W. What is the maximum voltage?

Accepted Answer

A)  10 V 
B)  20 V 
C)  30 V 
D)  40 V 
E)  50 V 
A)  10 V 
B)  20 V 
C)  30 V 
D)  40 V 
E)  50 V

Question 11

A 4.0 μF capacitor is connected in series with a 2.0 kΩ resistor across a 20-V DC source and an open switch. If the switch is closed at t = 0 s, what is the charge on the capacitor at t = 9 ms?

Accepted Answer

A)  0 C 
B)  37% of the minimum charge 
C)  68% of the maximum charge 
D)  68% of the minimum charge 
E)  96% of the maximum charge 
A)  0 C 
B)  37% of the minimum charge 
C)  68% of the maximum charge 
D)  68% of the minimum charge 
E)  96% of the maximum charge

Question 12

An RC circuit is connected across a DC voltage source through an open switch. The switch is closed at t = 0 s. Which of the following is a correct statement regarding the circuit?

Accepted Answer

A)  The capacitor charges to its maximum value in one time constant. 
B)  The capacitor charges to its maximum value in two time constants. 
C)  The resistor and the capacitor share the applied voltage equally as a function of time. 
D)  The current flows through the circuit even after the capacitor is fully charged. 
E)  Once the capacitor is fully charged, there is no current in the circuit. 
A)  The capacitor charges to its maximum value in one time constant. 
B)  The capacitor charges to its maximum value in two time constants. 
C)  The resistor and the capacitor share the applied voltage equally as a function of time. 
D)  The current flows through the circuit even after the capacitor is fully charged. 
E)  Once the capacitor is fully charged, there is no current in the circuit.

Question 13

The electromotive force of a battery is the maximum potential difference between the terminals of the battery.

Accepted Answer

A) True 
 B)False

Question 14

Kirchhoff's junction rule is a statement of

Accepted Answer

A)  the law of conservation of momentum. 
B)  the law of conservation of charge. 
C)  the law of conservation of energy. 
D)  the law of conservation of angular momentum. 
E)  Newton's second law. 
A)  the law of conservation of momentum. 
B)  the law of conservation of charge. 
C)  the law of conservation of energy. 
D)  the law of conservation of angular momentum. 
E)  Newton's second law.

Question 15

The resistivity of the material of a wire is 1.76 × 10-8 Ωm. If the diameter of the wire is 2 × 10-3 m and its length is 2 m, what is its resistance?

Accepted Answer

A)  112 Ω 
B)  11.2 Ω 
C)  1.12 Ω 
D)  0.112 Ω 
E)  0.0112 Ω 
A)  112 Ω 
B)  11.2 Ω 
C)  1.12 Ω 
D)  0.112 Ω 
E)  0.0112 Ω

Question 16

FIGURE 21-10  
-A 4-Ω resistor is connected in parallel with a 12-Ω resistor and this combination is connected to a 6-V DC power supply as shown in Figure 21-10. What is the current through the 12-Ω resistor?

Accepted Answer

A)  1.5 A 
B)  2.0 A 
C)  2.5 A 
D)  3.0 A 
E)  0.5 A 
A)  1.5 A 
B)  2.0 A 
C)  2.5 A 
D)  3.0 A 
E)  0.5 A

Question 17

A simple circuit has a total resistance of 30 Ω. If a 2.0-A current is maintained in this circuit, how much energy is dissipated in this circuit in 4.0 seconds?

Accepted Answer

A)  24 J 
B)  4.8 J 
C)  48 J 
D)  480 J 
E)  6.0 J 
A)  24 J 
B)  4.8 J 
C)  48 J 
D)  480 J 
E)  6.0 J

Question 18

Four unequal resistors are connected in a parallel circuit. Which one of the following statements is correct about this circuit?

Accepted Answer

A)  The total resistance is less than the smallest resistor. 
B)  The total resistance is equal to the average of the resistance of all the resistors. 
C)  The total resistance is equal to average of the four resistors. 
D)  The total resistance is more than the largest resistor. 
E)  None of the other answers is correct. 
A)  The total resistance is less than the smallest resistor. 
B)  The total resistance is equal to the average of the resistance of all the resistors. 
C)  The total resistance is equal to average of the four resistors. 
D)  The total resistance is more than the largest resistor. 
E)  None of the other answers is correct.

Question 19

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

Accepted Answer

A)  It stays the same. 
B)  It is doubled. 
C)  It is quadrupled. 
D)  It is reduced by a factor of 2. 
E)  It is reduced by a factor of 4. 
A)  It stays the same. 
B)  It is doubled. 
C)  It is quadrupled. 
D)  It is reduced by a factor of 2. 
E)  It is reduced by a factor of 4.

Question 20

The resistivity of a 1.0 m long wire is 1.72 × 10-8 Ωm and its cross sectional area is 2.0 × 10-6 m2. If the wire carries a current of 0.20 A, what is the voltage across the wire?

Accepted Answer

A)  17 mV 
B)  0.90 mV 
C)  1.7 mV 
D)  10 mV 
E)  90 mV 
A)  17 mV 
B)  0.90 mV 
C)  1.7 mV 
D)  10 mV 
E)  90 mV

Exam 21: Electric Current and Direct-Current Circuits

A 100-W light bulb is connected to a 110-V source. What current flows through the lamp?

The length of a certain wire is halved while the radius is doubled. What is the change in the resistance of this wire?

FIGURE 21-1 -Identify the junction nodes in the circuit shown in Figure 21-1.

FIGURE 21-18 -A 4.0 μF and a 6.0 μF capacitor are connected in series across an 8.0-V DC source. What is the charge on the 6.0 μF capacitor?

FIGURE 21-15 -Four resistors of values 2.0 Ω, 4.0 Ω, 3.0 Ω, and 9.0 Ω are connected across a DC source with voltage V as shown in Figure 21-15. If the total current through this circuit is 2.0 A, what is the current through the 4-Ω resistor?

Four unequal resistors are connected in a series circuit. Which one of the following statements is correct about this circuit?

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

Four unequal resistors connected in series have same current but different voltages.

Four resistors of 20 Ω, 40 Ω, 60 Ω, and 80 Ω are connected across a DC voltage source. If the current through this circuit is 0.5 A, what is the voltage applied to this circuit?

The power rating of a 400 Ω resistor is 0.25 W. What is the maximum voltage?

A 4.0 μF capacitor is connected in series with a 2.0 kΩ resistor across a 20-V DC source and an open switch. If the switch is closed at t = 0 s, what is the charge on the capacitor at t = 9 ms?

An RC circuit is connected across a DC voltage source through an open switch. The switch is closed at t = 0 s. Which of the following is a correct statement regarding the circuit?

The electromotive force of a battery is the maximum potential difference between the terminals of the battery.

Kirchhoff's junction rule is a statement of

The resistivity of the material of a wire is 1.76 × 10-8 Ωm. If the diameter of the wire is 2 × 10-3 m and its length is 2 m, what is its resistance?

FIGURE 21-10 -A 4-Ω resistor is connected in parallel with a 12-Ω resistor and this combination is connected to a 6-V DC power supply as shown in Figure 21-10. What is the current through the 12-Ω resistor?

A simple circuit has a total resistance of 30 Ω. If a 2.0-A current is maintained in this circuit, how much energy is dissipated in this circuit in 4.0 seconds?

Four unequal resistors are connected in a parallel circuit. Which one of the following statements is correct about this circuit?

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

The resistivity of a 1.0 m long wire is 1.72 × 10-8 Ωm and its cross sectional area is 2.0 × 10-6 m2. If the wire carries a current of 0.20 A, what is the voltage across the wire?

Introduction to Physics

One-Dimensional Kinematics

Vectors in Physics

Two-Dimensional Kinematics

Newtons Laws of Motion

Applications of Newtons Laws

Work and Kinetic Energy

Potential Energy and Conservation of Energy

Linear Momentum and Collisions

Rotational Kinematics and Energy

Rotational Dynamics and Static Equilibrium

Gravity

Oscillations About Equilibrium

Waves and Sound

Fluids

Temperature and Heat

Phases and Phase Changes

The Laws of Thermodynamics

Electric Charges, Forces, and Fields

Electric Potential and Electric Potential Energy

Magnetism

Magnetic Flux and Faradays Law of Induction

Alternating-Current Circuits

Electromagnetic Waves

Geometrical Optics

Optical Instruments

Physical Optics: Interference and Diffraction

Relativity

Quantum Physics

Atomic Physics

Nuclear Physics and Nuclear Radiation

Filters

The resistivity of the material of a wire is 1.76 × 10^-8 Ωm. If the diameter of the wire is 2 × 10^-3 m and its length is 2 m, what is its resistance?

The resistivity of a 1.0 m long wire is 1.72 × 10^-8 Ωm and its cross sectional area is 2.0 × 10^-6 m². If the wire carries a current of 0.20 A, what is the voltage across the wire?