Question 1

What is the current in the 15-Ω resistor when ε = 9.0 V?

Accepted Answer

A)  0.20 A 
B)  0.30 A 
C)  0.10 A 
D)  0.26 A 
E)  0.60 A 
A)  0.20 A 
B)  0.30 A 
C)  0.10 A 
D)  0.26 A 
E)  0.60 A

Question 2

A circuit consists of N resistors, all of resistance R, connected as shown below. A potential difference V is applied to the circuit. The equivalent resistance of the circuit is

Accepted Answer

A) 
  . 
B) 
  . 
C)  R. 
D)  NR. 
E)  2NR. 
A) 
  . 
B) 
  . 
C)  R. 
D)  NR. 
E)  2NR.

Question 3

A resistor of unknown resistance and a 15-Ω resistor are connected across a 20-V emf in such a way that a 2.0 A current is observed in the emf. What is the value of the unknown resistance?

Accepted Answer

A)  75 Ω 
B)  12 Ω 
C)  7.5 Ω 
D)  30 Ω 
E)  5.0 Ω 
A)  75 Ω 
B)  12 Ω 
C)  7.5 Ω 
D)  30 Ω 
E)  5.0 Ω

Question 4

A series circuit consists of a 100 V DC power source, a 100 Ω resistor, and a variable resistor of resistance R, which varies from 0 to 100 Ω. The current in the circuit is

Accepted Answer

A)  directly proportional to R. 
B)  inversely proportional to R. 
C)  directly proportional to (100 Ω + R). 
D)  inversely proportional to (100 Ω + R). 
E)  neither directly nor inversely proportional to R or to (100 Ω + R). 
A)  directly proportional to R. 
B)  inversely proportional to R. 
C)  directly proportional to (100 Ω + R). 
D)  inversely proportional to (100 Ω + R). 
E)  neither directly nor inversely proportional to R or to (100 Ω + R).

Question 5

If R = 4.0 kΩ, C = 3.0 mF, ε = 15 V, Q = 12 mC, and I = 2.0 mA, what is the potential difference Vb − Va?

Accepted Answer

A)  +3.0 V 
B)  −19 V 
C)  −3.0 V 
D)  +27 V 
E)  +21 V 
A)  +3.0 V 
B)  −19 V 
C)  −3.0 V 
D)  +27 V 
E)  +21 V

Question 6

Which of the identical light bulb(s) is(are) brightest when the capacitor has half its maximum charge?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  A and B 
E)  All three are equally bright. 
A)  A 
B)  B 
C)  C 
D)  A and B 
E)  All three are equally bright.

Question 7

A parallel circuit consists of a 100 V DC power source, a 100 Ω resistor, and a variable resistor of resistance R, which varies from 0 to 100 Ω. The current in the circuit is

Accepted Answer

A)  directly proportional to R. 
B)  inversely proportional to R. 
C)  directly proportional to (100 Ω + R). 
D)  inversely proportional to (100 Ω + R). 
E)  neither directly nor inversely proportional to R or to (100 Ω + R). 
A)  directly proportional to R. 
B)  inversely proportional to R. 
C)  directly proportional to (100 Ω + R). 
D)  inversely proportional to (100 Ω + R). 
E)  neither directly nor inversely proportional to R or to (100 Ω + R).

Question 8

A battery has an internal resistance of 4.0 Ω. Which of the following load resistors would have the most power delivered to it when connected across the battery?

Accepted Answer

A)  1.4 Ω 
B)  2.0 Ω 
C)  4.0 Ω 
D)  8.0 Ω 
E)  16 Ω 
A)  1.4 Ω 
B)  2.0 Ω 
C)  4.0 Ω 
D)  8.0 Ω 
E)  16 Ω

Question 9

At what rate is thermal energy generated in the 30-Ω resistor?

Accepted Answer

A)  20 W 
B)  27 W 
C)  60 W 
D)  13 W 
E)  30 W 
A)  20 W 
B)  27 W 
C)  60 W 
D)  13 W 
E)  30 W

Question 10

The circuit below contains three resistors, A, B, and C, which all have equal resistances. The emf ε = 110V. Which resistor generates the most thermal energy after the switch is closed?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  A and B 
E)  All three generate equal amounts of thermal energy. 
A)  A 
B)  B 
C)  C 
D)  A and B 
E)  All three generate equal amounts of thermal energy.

Question 11

What is the magnitude of the current in the 20-Ω resistor?

Accepted Answer

A)  0.75 A 
B)  0.00 A 
C)  0.25 A 
D)  0.50 A 
E)  1.00 A 
A)  0.75 A 
B)  0.00 A 
C)  0.25 A 
D)  0.50 A 
E)  1.00 A

Question 12

A 10-V battery is connected to a 15-Ω resistor and an unknown resistor R, as shown. The current in the circuit is 0.40 A. How much heat is produced in the 15-Ω resistor in 2.0 min?

Accepted Answer

A)  0.40 kJ 
B)  0.19 kJ 
C)  0.29 kJ 
D)  0.72 kJ 
E)  0.80 kJ 
A)  0.40 kJ 
B)  0.19 kJ 
C)  0.29 kJ 
D)  0.72 kJ 
E)  0.80 kJ

Question 13

The circuit below shows three resistors in parallel. R3 > R2 > R1. The resistors are all made of the same wire with the same diameter but have different lengths. Rank the magnitudes of the electric fields in the resistors from least to greatest.

Accepted Answer

A)  E3 2 1. 
B)  E2 1 = E3. 
C)  E1 = E2 = E3. 
D)  E1 = E3 2. 
E)  E1 2 3. 
A)  E3 2 1. 
B)  E2 1 = E3. 
C)  E1 = E2 = E3. 
D)  E1 = E3 2. 
E)  E1 2 3.

Question 14

In a loop in a closed circuit, the sum of the currents entering a junction equals the sum of the currents leaving a junction because

Accepted Answer

A)  the potential of the nearest battery is the potential at the junction. 
B)  there are no transformations of energy from one type to another in a circuit loop. 
C)  capacitors tend to maintain current through them at a constant value. 
D)  current is used up after it leaves a junction. 
E)  charge is neither created nor destroyed at a junction. 
A)  the potential of the nearest battery is the potential at the junction. 
B)  there are no transformations of energy from one type to another in a circuit loop. 
C)  capacitors tend to maintain current through them at a constant value. 
D)  current is used up after it leaves a junction. 
E)  charge is neither created nor destroyed at a junction.

Question 15

Determine the resistance R when I = 1.5 A.

Accepted Answer

A)  40 Ω 
B)  8.0 Ω 
C)  85 Ω 
D)  28 Ω 
E)  32 Ω 
A)  40 Ω 
B)  8.0 Ω 
C)  85 Ω 
D)  28 Ω 
E)  32 Ω

Question 16

If Q = 400 μC and the potential difference VA − VB = −10 V in the circuit segment shown below, what is the current in the resistor?

Accepted Answer

A)  1.0 mA right to left 
B)  1.0 mA left to right 
C)  3.5 mA right to left 
D)  3.5 mA left to right 
E)  None of the above 
A)  1.0 mA right to left 
B)  1.0 mA left to right 
C)  3.5 mA right to left 
D)  3.5 mA left to right 
E)  None of the above

Question 17

Determine the magnitude and sense (direction) of the current in the 500-Ω resistor when I = 30 mA.

Accepted Answer

A)  56 mA left to right 
B)  56 mA right to left 
C)  48 mA left to right 
D)  48 mA right to left 
E)  26 mA left to right 
A)  56 mA left to right 
B)  56 mA right to left 
C)  48 mA left to right 
D)  48 mA right to left 
E)  26 mA left to right

Question 18

If the current in the 4.0-Ω resistor is 1.4 A, what is the magnitude of the potential difference, VA − VB?

Accepted Answer

A)  69 V 
B)  55 V 
C)  62 V 
D)  48 V 
E)  31 V 
A)  69 V 
B)  55 V 
C)  62 V 
D)  48 V 
E)  31 V

Question 19

How long will it take a charged 80-μF capacitor to lose 20% of its initial energy when it is allowed to discharge through a 45-Ω resistor?

Accepted Answer

A)  0.92 ms 
B)  0.64 ms 
C)  0.40 ms 
D)  0.19 ms 
E)  0.80 ms 
A)  0.92 ms 
B)  0.64 ms 
C)  0.40 ms 
D)  0.19 ms 
E)  0.80 ms

Question 20

The circuit below contains 3 100-W light bulbs and a capacitor. The emf is 110 V. Which light bulb(s) is(are) brightest? (Assume the capacitor is fully charged.)

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  A and B 
E)  All three are equally bright. 
A)  A 
B)  B 
C)  C 
D)  A and B 
E)  All three are equally bright.

Exam 28: Direct-Current Circuits

What is the current in the 15-Ω resistor when ε = 9.0 V?

A circuit consists of N resistors, all of resistance R, connected as shown below. A potential difference V is applied to the circuit. The equivalent resistance of the circuit is

A resistor of unknown resistance and a 15-Ω resistor are connected across a 20-V emf in such a way that a 2.0 A current is observed in the emf. What is the value of the unknown resistance?

A series circuit consists of a 100 V DC power source, a 100 Ω resistor, and a variable resistor of resistance R, which varies from 0 to 100 Ω. The current in the circuit is

If R = 4.0 kΩ, C = 3.0 mF, ε = 15 V, Q = 12 mC, and I = 2.0 mA, what is the potential difference Vb − Va?

Which of the identical light bulb(s) is(are) brightest when the capacitor has half its maximum charge?

A parallel circuit consists of a 100 V DC power source, a 100 Ω resistor, and a variable resistor of resistance R, which varies from 0 to 100 Ω. The current in the circuit is

A battery has an internal resistance of 4.0 Ω. Which of the following load resistors would have the most power delivered to it when connected across the battery?

At what rate is thermal energy generated in the 30-Ω resistor?

The circuit below contains three resistors, A, B, and C, which all have equal resistances. The emf ε = 110V. Which resistor generates the most thermal energy after the switch is closed?

What is the magnitude of the current in the 20-Ω resistor?

A 10-V battery is connected to a 15-Ω resistor and an unknown resistor R, as shown. The current in the circuit is 0.40 A. How much heat is produced in the 15-Ω resistor in 2.0 min?

The circuit below shows three resistors in parallel. R3 > R2 > R1. The resistors are all made of the same wire with the same diameter but have different lengths. Rank the magnitudes of the electric fields in the resistors from least to greatest.

In a loop in a closed circuit, the sum of the currents entering a junction equals the sum of the currents leaving a junction because

Determine the resistance R when I = 1.5 A.

If Q = 400 μC and the potential difference VA − VB = −10 V in the circuit segment shown below, what is the current in the resistor?

Determine the magnitude and sense (direction) of the current in the 500-Ω resistor when I = 30 mA.

If the current in the 4.0-Ω resistor is 1.4 A, what is the magnitude of the potential difference, VA − VB?

How long will it take a charged 80-μF capacitor to lose 20% of its initial energy when it is allowed to discharge through a 45-Ω resistor?

The circuit below contains 3 100-W light bulbs and a capacitor. The emf is 110 V. Which light bulb(s) is(are) brightest? (Assume the capacitor is fully charged.)

Physics and Measurement

Motion in One Dimension

Vectors

Motion in Two Dimensions

The Laws of Motion

Circular Motion and Other Applications of Newtons Laws

Energy of a System

Conservation of Energy

Linear Momentum and Collisions

Rotation of a Rigid Object About a Fixed Axis

Angular Momentum

Static Equilibrium and Elasticity

Universal Gravitation

Fluid Mechanics

Oscillatory Motion

Wave Motion

Superposition and Standing Waves

Temperature

The First Law of Thermodynamics

The Kinetic Theory of Gases

Heat Engines, Entropy, and the Second Law of Thermodynamics

Electric Fields

Gausss Law

Electric Potential

Capacitance and Dielectrics

Current and Resistance

Magnetic Fields

Sources of the Magnetic Field

Faradays Law

Inductance

Alternating-Current Circuits

Electromagnetic Waves

The Nature of Light and the Principles of Ray Optics

Image Formation

Wave Optics

Diffraction Patterns and Polarization

Relativity

Introduction to Quantum Physics

Quantum Mechanics

Atomic Physics

Molecules and Solids

Nuclear Structure

Particle Physics and Cosmology

Filters

If R = 4.0 kΩ, C = 3.0 mF, ε = 15 V, Q = 12 mC, and I = 2.0 mA, what is the potential difference V_b − V_a?

The circuit below shows three resistors in parallel. R₃ > R₂ > R₁. The resistors are all made of the same wire with the same diameter but have different lengths. Rank the magnitudes of the electric fields in the resistors from least to greatest.

If Q = 400 μC and the potential difference V_A − V_B = −10 V in the circuit segment shown below, what is the current in the resistor?

If the current in the 4.0-Ω resistor is 1.4 A, what is the magnitude of the potential difference, V_A − V_B?