Physics
Physics
1st Edition
Walker
ISBN: 9780133256925
Table of contents
Textbook solutions

All Solutions

Page 827: Lesson Check

Exercise 7
Step 1
1 of 2
The magnitude of the induced emf is given by Faraday’s law:

$$
begin{align*}
abs{varepsilon}=Nabs{frac{Delta Phi}{Delta t}} ,.
end{align*}
$$

The factor $dfrac{Delta Phi}{Delta t}$ is the rate of change of the flux of the magnetic field through a coil. The quicker the magnetic field (its flux through the coil) changes, the absolute value of $dfrac{Delta Phi}{Delta t}$ is greater. Thus, a magnetic field that changes quickly rather than slowly, induces a greater emf.

Result
2 of 2
A magnetic field that changes quickly rather than slowly, induces a greater emf.
Exercise 8
Step 1
1 of 2
The expression for the magnetic flux through a wire loop is

$$
begin{align*}
Phi=BAcos{theta} ,.
end{align*}
$$

If we double the area of the loop $A$ and halve the magnetic field $B$ the flux becomes

$$
begin{align*}
Phi&=frac{B}{2}2Acos{theta} \
&=BAcos{theta} ,,
end{align*}
$$

which is the same as the starting flux. Thus, the flux doesn’t change when the area of the wire loop is doubled an the magnetic field is halved.

Result
2 of 2
The flux doesn’t change when the area of the wire loop is doubled an the magnetic field is halved.
Exercise 9
Step 1
1 of 2
Lenz’s law tells us that the direction of the induced current is such that it opposes the change which caused it. For example, an increasing magnetic flux through a wire loop induces a current in the wire which generates a magnetic field that opposes the change in the flux through the loop.
Result
2 of 2
Lenz’s law tells us that the direction of the induced current is such that it opposes the change which caused it.
Exercise 10
Result
1 of 1
Constant magnetic fields don’t produce electric fields. Changing magnetic fields produce electric fields.
Exercise 11
Step 1
1 of 2
The magnetic flux through a wire loop is given by

$$
begin{align*}
Phi=BAcos{theta} ,.
end{align*}
$$

The magnitude of the magnetic field $B$ and the area of the loop $A$ are the same for the loops 1 and 2. The angle between the normal to the loop and the magnetic field, $theta$, is equal to $10^{circ}$ and $20^{circ}$ for the loops 1 and 2, respectively. Because

$$
begin{align*}
cos{10^{circ}}>cos{20^{circ}} ,,
end{align*}
$$

the flux through loop 1 is greater than the flux through loop 2.

Result
2 of 2
The flux through loop 1 is greater than the flux through loop 2.
Exercise 12
Step 1
1 of 1
When the coil is moving along $y$ axis, there is no change in the
field, hence there will be no current. So for coil 2 and 4 the current
is zero.

When the coil is moving towards positive $x$ axis, the field is increasing,
so the current should be such that this change is opposed, that is
induced field should point into the page. So, the current should be
clockwise for loop 1.

When the loop is moving towards negative $x$ axis, the field is decreasing.
Hence, to oppose the change, the induced field should be in point
out of the page. So, the current should be counterclockwise for loop
3.

Exercise 13
Step 1
1 of 3
The magnetic flux in the loop is given by the equation:

$$
begin{align*}
Phi&=Bcdot{A}cdotcos theta
end{align*}
$$

Where $B$ represents the magnitude of the magnetic field, $A$ stands for the area of the loop, and $theta$ stands for the loop orientation regarding the direction of the magnetic field.

Let’s compute the area of the loop:

$$
begin{align*}
A&=acdot{b}\
A&=0.32text{ m}cdot{0.16text{ m}}\
A&=0.0512text{m}^2
end{align*}
$$

$bold{a)}$

In case that the magnetic field is perpendicular to a plan of the loop, the angle between them is $theta=0text{textdegree}$. So, the flux will be:

$$
begin{align*}
Phi&=Bcdot{A}cdotcos theta\
Phi&=0.77text{ T}cdot{0.0512text{m}^2}cdotcos{0text{textdegree}}
end{align*}
$$

$$
boxed{Phi=0.0394text{ T}cdottext{m}^2}
$$

Step 2
2 of 3
$bold{b)}$

In case that the magnetic field is paralel to a plan of the loop, the angle between them is $theta=90text{textdegree}$. So, the flux will be:

$$
begin{align*}
Phi&=Bcdot{A}cdotcos theta\
Phi&=0.77text{ T}cdot{0.0512text{m}^2}cdotcos{90text{textdegree}}
end{align*}
$$

$$
boxed{Phi=0}
$$

Result
3 of 3
a) $Phi=0.0394text{ T}cdottext{m}^2$

b) $Phi=0$

Exercise 14
Step 1
1 of 2
The induced emf in the loop that is in a variable magnetic field is given by Faraday’s law as:

$$
begin{align*}
|varepsilon|=Ncdotleft|frac{DeltaPhi}{Delta{t}}right|
end{align*}
$$

As we have the single loop of wire the $N=1$, let’s express the time and substitute:

$$
begin{align*}
|Delta{t}|&=Ncdotleft|frac{DeltaPhi}{varepsilon}right|\
|Delta{t}|&=1cdotleft|frac{0.85text{ T}cdot{ m}^2-0.110text{ T}cdot{ m}^2}{1.48text{ V}}right|\
|Delta{t}|&=1cdotleft|frac{0.74text{ T}cdot{ m}^2}{1.48text{ V}}right|
end{align*}
$$

The time needed for a change in a flux is:

$$
boxed{Delta{t}=0.5text{ s}}
$$

Result
2 of 2
$$
Delta{t}=0.5text{ s}
$$
Exercise 15
Step 1
1 of 2
The induced emf in the loop that is in a variable magnetic field is given by Faraday’s law as:

$$
begin{align*}
|varepsilon|=Ncdotleft|frac{DeltaPhi}{Delta{t}}right|
end{align*}
$$

Where the $N$ stands for the number of loops, $DeltaPhi$ is the magnitude of change in flux, $Delta{t}$ stands for time that is needed for the change in flux, and $varepsilon$ is induced emf.

If we express the change in flux from this equation, we get:

$$
begin{align*}
|DeltaPhi|&=left|frac{varepsiloncdotDelta{t}}{N}right|
end{align*}
$$

Ler’s substitute and compute the magnitude of change in flux:

$$
begin{align*}
|DeltaPhi|&=left|frac{2.6text{ V}cdot{0.35text{ s}}}{25}right|
end{align*}
$$

The magnitude of change in flux is:

$$
boxed{DeltaPhi=0.0364text{ T}cdottext{ m}^2}
$$

Result
2 of 2
$$
DeltaPhi=0.0364text{ T}cdottext{ m}^2
$$
Exercise 16
Step 1
1 of 2
The magnetic flux through the loop of wire that is into a magnetic field is given by the equation:

$$
begin{align*}
Phi&=Bcdot{A}cdotcos theta
end{align*}
$$

Where $B$ represents the magnitude of the magnetic field, $A$ stands for the area of the loop, and $theta$ stands for the loop orientation regarding the direction of the magnetic field.

Let’s express the angle from this equation:

$$
begin{align*}
cos theta&=frac{Phi}{Bcdot{A}}\
theta&=arccos {frac{Phi}{Bcdot{A}}}
end{align*}
$$

Let’s substitute and compute:

$$
begin{align*}
theta&=arccos{left(frac{7.1cdot{10^{-4}}text{ T}cdottext{ m}^2}{0.45text{ T}cdot{0.085text{ m}^2}}right)}\
theta&=arccos {left(0.0185621right)}
end{align*}
$$

$$
boxed{theta=88.94text{textdegree}}
$$

Result
2 of 2
$$
theta=88.94text{textdegree}
$$
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Chapter 1: Introduction to Physics
Section 1.1: Physics and the Scientific Method
Section 1.2: Physics and Society
Section 1.3: Units and Dimensions
Section 1.4: Basic Math for Physics
Page 38: Assessment
Page 41: Standardized Test Prep
Chapter 2: Introduction to Motion
Section 2.1: Describing Motion
Section 2.2: Speed and Velocity
Section 2.3: Position-Time Graphs
Section 2.4: Equation of Motion
Page 66: Assessment
Page 71: Standardized Test Prep
Page 45: Practice Problems
Page 47: Practice Problems
Page 47: Lesson Check
Page 49: Practice Problems
Page 52: Practice Problems
Page 53: Lesson Check
Page 56: Practice Problems
Page 57: Lesson Check
Page 59: Practice Problems
Page 60: Practice Problems
Page 62: Practice Problems
Page 62: Lesson Check
Chapter 3: Acceleration and Acceleration Motion
Section 3.1: Acceleration
Section 3.2: Motion with Constant Acceleration
Section 3.3: Position-Time Graphs for Constant Acceleration
Section 3.4: Free Fall
Page 105: Assessment
Page 111: Standardized Test Prep
Chapter 4: Motion in Two Dimensions
Section 4.1: Vectors in Physics
Section 4.2: Adding and Subtracting Vectors
Section 4.3: Relative Motion
Section 4.4: Projectile Motion
Page 144: Assessment
Page 149: Standardized Test Prep
Chapter 5: Newton’s Laws of Motion
Section 5.1: Newton’s Laws of Motion
Section 5.2: Applying Newton’s Laws
Section 5.3: Friction
Page 180: Assessment
Page 187: Standardized Test Prep
Chapter 6: Work and Energy
Section 6.1: Work
Section 6.2: Work and Energy
Section 6.3: Conservation of Energy
Section 6.4: Power
Page 220: Assessment
Page 227: Standardized Test Prep
Page 191: Practice Problems
Page 193: Practice Problems
Page 196: Lesson Check
Page 196: Practice Problems
Page 199: Practice Problems
Page 201: Practice Problems
Page 203: Practice Problems
Page 204: Practice Problems
Page 205: Practice Problems
Page 206: Lesson Check
Page 209: Practice Problems
Page 211: Lesson Check
Page 213: Practice Problems
Page 214: Practice Problems
Page 215: Practice Problems
Page 216: Lesson Check
Chapter 7: Linear Momentum and Collisions
Section 7.1: Momentum
Section 7.2: Impulse
Section 7.3: Conservation of Momentum
Section 7.4: Collisions
Page 260: Assessment
Page 265: Standardized Test Prep
Chapter 8: Rotational Motion and Equilibrium
Section 8.1: Describing Angular Motion
Section 8.2: Rolling Motion and the Moment of Inertia
Section 8.3: Torque
Section 8.4: Static Equilibrium
Page 300: Assessment
Page 305: Standardized Test Prep
Page 269: Practice Problems
Page 271: Practice Problems
Page 272: Practice Problems
Page 275: Practice Problems
Page 275: Lesson Check
Page 277: Practice Problems
Page 280: Lesson Check
Page 284: Practice Problems
Page 286: Practice Problems
Page 287: Practice Problems
Page 289: Lesson Check
Page 294: Practice Problems
Page 295: Practice Problems
Page 296: Lesson Check
Chapter 9: Gravity and Circular Motion
Section 9.1: Newton’s Law of Universal Gravity
Section 9.2: Applications of Gravity
Section 9.3: Circular Motion
Section 9.4: Planetary Motion and Orbits
Page 336: Assessment
Page 341: Standardized Test Prep
Chapter 10: Temperature and Heat
Section 10.1: Temperature, Energy, and Heat
Section 10.2: Thermal Expansion and Energy Transfer
Section 10.3: Heat Capacity
Section 10.4: Phase Changes and Latent Heat
Page 378: Assessment
Page 383: Standardized Test Prep
Chapter 11: Thermodynamics
Section 11.1: The First Law of Thermodynamics
Section 11.2: Thermal Processes
Section 11.3: The Second and Third Laws of Thermodynamics
Page 410: Assessment
Page 413: Standardized Test Prep
Chapter 12: Gases, Liquids, and Solids
Section 12.1: Gases
Section 12.2: Fluids at Rest
Section 12.3: Fluids in Motion
Section 12.4: Solids
Page 446: Assessment
Page 451: Standardized Test Prep
Chapter 13: Oscillations and Waves
Section 13.1: Oscillations and Periodic Motion
Section 13.2: The Pendulum
Section 13.3: Waves and Wave Properties
Section 13.4: Interacting Waves
Page 486: Assessment
Page 491: Standardized Test Prep
Chapter 14: Sound
Section 14.1: Sound Waves and Beats
Section 14.2: Standing Sound Waves
Section 14.3: The Doppler Effect
Section 14.4: Human Perception of Sound
Page 523: Assessment
Page 527: Standardized Test Prep
Page 495: Practice Problems
Page 496: Practice Problems
Page 500: Practice Problems
Page 501: Lesson Check
Page 503: Practice Problems
Page 504: Practice Problems
Page 506: Practice Problems
Page 506: Lesson Check
Page 510: Practice Problems
Page 511: Practice Problems
Page 512: Lesson Check
Page 514: Practice Problems
Page 516: Practice Problems
Page 517: Practice Problems
Page 519: Lesson Check
Chapter 15: The Properties of Lights
Section 15.1: The Nature of Light
Section 15.2: Color and the Electromagnetic Spectrum
Section 15.3: Polarization and Scattering of Light
Page 557: Assessment
Page 563: Standardized Test Prep
Chapter 16: Reflection and Mirrors
Section 16.1: The Reflection of Light
Section 16.2: Plane Mirrors
Section 16.3: Curved Mirrors
Page 590: Assessment
Page 595: Standardized Test Prep
Chapter 17: Refraction and Lenses
Section 17.1: Refraction
Section 17.2: Applications of Refraction
Section 17.3: Lenses
Section 17.4: Applications of Lenses
Page 629: Assessment
Page 635: Standardized Test Prep
Chapter 18: Interference and Diffraction
Section 18.1: Interference
Section 18.2: Interference in Thin Films
Section 18.3: Diffraction
Section 18.4: Diffraction Gratings
Page 668: Assessment
Page 673: Standardized Test Prep
Chapter 19: Electric Charges and Forces
Section 19.1: Electric Charge
Section 19.2: Electric Force
Section 19.3: Combining Electric Forces
Page 698: Assessment
Page 703: Standardized Test Prep
Chapter 20: Electric Fields and Electric Energy
Section 20.1: The Electric Field
Section 20.2: Electric Potential Energy and Electric Potential
Section 20.3: Capacitance and Energy Storage
Page 738: Assessment
Page 743: Standardized Test Prep
Chapter 21: Electric Current and Electric Circuits
Section 21.1: Electric Current, Resistance, and Semiconductors
Section 21.2: Electric Circuits
Section 21.3: Power and Energy in Electric Circuits
Page 775: Assessment
Page 781: Standardized Test Prep
Chapter 22: Magnetism and Magnetic Fields
Section 22.1: Magnets and Magnetic Fields
Section 22.2: Magnetism and Electric Currents
Section 22.3: The Magnetic Force
Page 810: Assessment
Page 815: Standardized Test Prep
Chapter 23: Electromagnetic Induction
Section 23.1: Electricity from Magnetism
Section 23.2: Electric Generators and Motors
Section 23.3: AC Circuits and Transformers
Page 844: Assessment
Page 849: Standardized Test Prep
Chapter 24: Quantum Physics
Section 24.1: Quantized Energy and Photons
Section 24.2: Wave-Particle Duality
Section 24.3: The Heisenberg Uncertainty Principle
Page 876: Assessment
Page 881: Standardized Test Prep
Chapter 26: Nuclear Physics
Section 26.1: The Nucleus
Section 26.2: Radioactivity
Section 26.3: Applications of Nuclear Physics
Section 26.4: Fundamental Forces and Elementary Particles
Page 944: Assessment
Page 947: Standardized Test Prep