Question 1

What is the energy density in the magnetic field 25 cm from a long straight wire carrying a current of 12 A? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  7.3 × 10-5 J/m3 
B)  3.7 × 10-5 J/m3 
C)  3.6 × 10-4 J/m3 
D)  1.2 × 10-4 J/m3 
E)  The density cannot be determined without knowing the volume. 
A)  7.3 × 10-5 J/m3 
B)  3.7 × 10-5 J/m3 
C)  3.6 × 10-4 J/m3 
D)  1.2 × 10-4 J/m3 
E)  The density cannot be determined without knowing the volume.

Question 2

A series circuit consists of a 0.55-H inductor with internal resistance of 8.0 Ω connected in series with a 4.0-Ω resistor, an open switch, and an ideal 12-V battery.
(a) When the switch is closed, what is the initial current through the 4.0-Ω resistor?
(b) What is the current through the 4.0-Ω resistor a very long time after the switch is closed?

Accepted Answer

(a) 0.00 A

Question 3

An LC circuit consists of a 3.4-µF capacitor and a coil with a self-inductance 0.080 H and no appreciable resistance. At t = 0 the capacitor has a charge of 5.4 µC and the current in the inductor is zero.
(a) How long after t = 0 will the current in the circuit be maximum?
(b) What will be this maximum current?

Accepted Answer

(a) 0.82 m

Question 4

How much energy is stored in a room 3.0 m by 4.0 m by 2.4 m due to the earth's magnetic field with a strength of 5.0 × 10-5 T? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  570 mJ. 
B)  29 mJ. 
C)  10 mJ. 
D)  100 mJ. 
E)  570   mJ. 
A)  570 mJ. 
B)  29 mJ. 
C)  10 mJ. 
D)  100 mJ. 
E)  570   mJ.

Question 5

For the circuit shown in the figure, the switch has been open for a very long time.   
(a) What is the potential drop across the 15.0-mH inductor just after closing the switch?
(b) What is the potential drop across the 70.0-µF capacitor after the switch has been closed for a very long time?

Accepted Answer

(a) 150.0

Question 6

Which of the following statements about inductors are correct? There may be more than one correct choice.

Accepted Answer

A)  When it is connected in a circuit, an inductor always resists having current flow through it. 
B)  Inductors store energy by building up charge. 
C)  When an inductor and a resistor are connected in series with a DC battery, the current in the circuit is reduced to zero in one time constant. 
D)  An inductor always resists any change in the current through it. 
E)  When an inductor and a resistor are connected in series with a DC battery, the current in the circuit is zero after a very long time. 
A)  When it is connected in a circuit, an inductor always resists having current flow through it. 
B)  Inductors store energy by building up charge. 
C)  When an inductor and a resistor are connected in series with a DC battery, the current in the circuit is reduced to zero in one time constant. 
D)  An inductor always resists any change in the current through it. 
E)  When an inductor and a resistor are connected in series with a DC battery, the current in the circuit is zero after a very long time.

Exam 29: Inductance

What is the energy density in the magnetic field 25 cm from a long straight wire carrying a current of 12 A? (μ0 = 4π × 10-7 T ∙ m/A)

How much energy is stored in a room 3.0 m by 4.0 m by 2.4 m due to the earth's magnetic field with a strength of 5.0 × 10-5 T? (μ0 = 4π × 10-7 T ∙ m/A)

For the circuit shown in the figure, the switch has been open for a very long time. (a) What is the potential drop across the 15.0-mH inductor just after closing the switch? (b) What is the potential drop across the 70.0-µF capacitor after the switch has been closed for a very long time?

Which of the following statements about inductors are correct? There may be more than one correct choice.

Units, Physical Quantities, and Vectors

Motion Along a Straight Line

Motion in Two or Three Dimensions

Newtons Laws of Motion

Applying Newtons Laws

Work and Kinetic Energy

Potential Energy and Energy Conservation

Momentum, Impulse, and Collisions

Rotation of Rigid Bodies

Equilibrium and Elasticity

Fluid Mechanics

Gravitation

Periodic Motion

Mechanical Waves

Sound and Hearing

Temperature and Heat

Thermal Properties of Matter

The First Law of Thermodynamics

The Second Law of Thermodynamics

Electric Charge and Electric Field

Gausss Law

Electric Potential

Capacitance and Dielectrics

Current, Resistance, and Electromotive Force

Direct-Current Circuits

Magnetic Field and Magnetic Forces

Sources of Magnetic Field

Electromagnetic Induction

Alternating Current

Electromagnetic Waves

The Nature and Propagation of Light

Geometric Optics

Interference

Diffraction

Relativity

Photons: Light Waves Behaving As Particles

Particles Behaving As Waves

Quantum Mechanics

Atomic Structure

Molecules and Condensed Matter

Nuclear Physics

Particle Physics and Cosmology

Filters

What is the energy density in the magnetic field 25 cm from a long straight wire carrying a current of 12 A? (μ₀ = 4π × 10^-7 T ∙ m/A)

How much energy is stored in a room 3.0 m by 4.0 m by 2.4 m due to the earth's magnetic field with a strength of 5.0 × 10^-5T? (μ₀= 4π × 10^-7 T ∙ m/A)