Margins Study Assistant

Chapter 1

Introduction: The Nature of Science and Physics

Summary

The four fundamental units we will use in this text are the meter (for length), the kilogram (for mass), the second (for time), and the ampere (for electric current). All units can be expressed as combinations of four fundamental units Physics is the most basic of the sciences, concerning itself with energy, matter, space and time, and their interactions Scientific laws and theories express the general truths of nature and the body of knowledge they encompass.

Key terms

physics: the science concerned with describing the interactions of energy, matter, space, and time; it is especially interested in what fundamental mechanisms underlie every phenomenon
law: a description, using concise language or a mathematical formula, a generalized pattern in nature that is supported by scientific evidence and repeated experiments
fundamental units: units that can only be expressed relative to the procedure used to measure them
units: a standard used for expressing and comparing measurements
meter: the SI unit for length, abbreviated (m)
kilogram: the SI unit for mass, abbreviated (kg)
second: the SI unit for time, abbreviated (s)
method of adding percents: the percent uncertainty in a quantity calculated by multiplication or division is the sum of the percent uncertainties in the items used to make the calculation

Chapter 2

Kinematics

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Summary

In symbols, displacement Δ x is defined to be Δ x = x f - x 0 , where x 0 is the initial position and x f is the final position. Displacement is the change in position of an object The SI unit for displacement is the meter (m). Kinematics is the study of motion without considering its causes.

Key terms

kinematics: the study of motion without considering its causes
position: the location of an object at a particular time
displacement: the change in position of an object
independent variable: the variable that the dependent variable is measured with respect to; usually plotted along the x -axis
dependent variable: the variable that is being measured; usually plotted along the y -axis
scalar: a quantity that is described by magnitude, but not direction

Chapter 3

Two-Dimensional Kinematics

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Summary

The graphical method of adding vectors A and B involves drawing vectors on a graph and adding them using the head-to-tail method. The resultant vector R is defined such that A + B = R . In two dimensions, this path can be represented by a vector with horizontal and vertical components The horizontal and vertical components of a vector are independent of one another.

Key terms

kinematics: the study of motion without regard to mass or force
head-to-tail method: a method of adding vectors in which the tail of each vector is placed at the head of the previous vector
vector: a quantity that has both magnitude and direction; an arrow used to represent quantities with both magnitude and direction
tail: the start point of a vector; opposite to the head or tip of the arrow
magnitude and direction of R: then determined with a ruler and protractor, respectively
motion: displacement of an object as a function of time
resultant vector: the vector sum of two or more vectors
resultant: the sum of two or more vectors

Chapter 4

Dynamics: Force and Newton's Laws of Motion

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Summary

Newton’s first law of motion states that a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force. A free-body diagram is a drawing of all external forces acting on a body Dynamics is the study of how forces affect the motion of objects External forces are any outside forces that act on a body.

Key terms

force: a push or pull on an object with a specific magnitude and direction; can be represented by vectors; can be expressed as a multiple of a standard force
dynamics: the study of how forces affect the motion of objects and systems
free-body diagram: a sketch showing all of the external forces acting on an object or system; the system is represented by a dot, and the forces are represented by vectors extending outward from…
Newton’s first law of motion: a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force; also known as the law of inertia
net external force: the vector sum of all external forces acting on an object or system; causes a mass to accelerate
external force: a force acting on an object or system that originates outside of the object or system
inertia: the tendency of an object to remain at rest or remain in motion
mass: the quantity of matter in a substance; measured in kilograms

Chapter 5

Further Applications of Newton's Laws: Friction, Drag, and Elasticity

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Summary

The magnitude of static friction f s between systems stationary relative to one another is given by f s ≤ μ s N , where μ s is the coefficient of static friction, which depends on both of the materials Simple friction is proportional to the normal force N pushing the systems together. (A normal force is always perpendicular to the contact surface between systems.) Friction depends on both of the materials involved. The kinetic friction force f k between systems moving relative to one another is given by f k = μ k N , where μ k is the coefficient of kinetic friction, which also depends on both materials

Key terms

friction: a force that opposes relative motion or attempts at motion between systems in contact
drag force: F D , found to be proportional to the square of the speed of the object; mathematically F D ∝ v 2 F D = 1 2 Cρ Av 2 , where C is the drag coefficient, A is the area of the object…
Stokes’ law: F s = 6 πrηv , where r is the radius of the object, η is the viscosity of the fluid, and v is the object’s velocity
static friction: a force that opposes the motion of two systems that are in contact and are not moving relative to one another
magnitude of static friction: f s ≤ μ s N , where μ s is the coefficient of static friction and N is the magnitude of the normal force
kinetic friction: a force that opposes the motion of two systems that are in contact and moving relative to one another
normal force: always perpendicular to the contact surface between systems.) Friction depends on both of the materials involved
magnitude of kinetic friction: f k = μ k N , where μ k is the coefficient of kinetic friction

Chapter 6

Uniform Circular Motion and Gravitation

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Summary

The units of angular velocity are radians per second (rad/s). The rotation angle Δ θ is defined as the ratio of the arc length to the radius of curvature: Δ θ = Δ s r , where arc length Δ s is distance traveled along a circular path and r is the radius of curvature of the… The quantity Δ θ is measured in units of radians (rad), for which 2π rad = 360º = 1 revolution Centripetal acceleration a c is the acceleration experienced while in uniform circular motion.

Key terms

uniform circular motion: the motion of an object in a circular path at constant speed
rotation angle: the ratio of the arc length to the radius of curvature on a circular path: Δ θ = Δ s r
angular velocity: ω , the rate of change of the angle with which an object moves on a circular path
centripetal acceleration: the acceleration of an object moving in a circle, directed toward the center
quantity Δ θ: measured in units of radians (rad), for which 2π rad = 360º = 1 revolution
arc length: Δ s , the distance traveled by an object along a circular path
radians: a unit of angle measurement
units of angular velocity: radians per second (rad/s)

Chapter 7

Work, Energy, and Energy Resources

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Summary

The net work W net is the work done by the net force acting on an object The SI unit for work and energy is the joule (J), where 1 J = 1 N ⋅ m = 1 kg ⋅ m 2 /s 2 The work done by a force is zero if the displacement is either zero or perpendicular to the force Work done on an object transfers energy to the object

Key terms

work: the transfer of energy by a force that causes an object to be displaced; the product of the component of the force in the direction of the displacement and the magnitude of the…
work done by a force: zero if the displacement is either zero or perpendicular to the force
kinetic energy: the energy an object has by reason of its motion, equal to 1 2 mv 2 for the translational (i.e., non-rotational) motion of an object of mass m moving at speed v
work done: positive if the force and displacement have the same direction, and negative if they have opposite direction
net work: work done by the net force, or vector sum of all the forces, acting on an object
joule: SI unit of work and energy, equal to one newton-meter
net work W net: the work done by the net force acting on an object

Chapter 8

Linear Momentum and Collisions

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Summary

Newton’s second law of motion in terms of momentum states that the net external force equals the change in momentum of a system divided by the time over which it changes In symbols, Newton’s second law of motion is defined to be F net = Δ p Δ t , F net is the net external force, Δ p is the change in momentum, and Δ t is the change time Impulse, or change in momentum, equals the average net external force multiplied by the time this force acts: Δ p = F net Δ t The conservation of momentum principle is written p tot = constant or p tot = p ′ tot ( isolated system ) , p tot is the initial total momentum and p ′ tot is the total momentum some time later

Key terms

linear momentum: the product of mass and velocity
conservation of momentum principle: when the net external force is zero, the total momentum of the system is conserved or constant
isolated system: a system in which the net external force is zero
second law of motion: physical law that states that the net external force equals the change in momentum of a system divided by the time over which it changes
change in momentum: the difference between the final and initial momentum; the mass times the change in velocity
impulse: the average net external force times the time it acts; equal to the change in momentum
inelastic collision: a collision in which internal kinetic energy is not conserved
quark: fundamental constituent of matter and an elementary particle

Chapter 9

Statics and Torque

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Summary

The second condition assures those torques are also balanced. The perpendicular lever arm r ⊥ is defined to be r ⊥ = r sin θ so that τ = r ⊥ F The perpendicular lever arm r ⊥ is the shortest distance from the pivot point to the line along which F acts. The SI unit for torque is newton-meter (N·m) .

Key terms

torque: turning or twisting effectiveness of a force
perpendicular lever arm: the shortest distance from the pivot point to the line along which F lies
perpendicular lever arm r ⊥: defined to be r ⊥ = r sin θ so that τ = r ⊥ F
dynamic equilibrium: a state of equilibrium in which the net external force and torque on a system moving with constant velocity are zero
neutral equilibrium: a state of equilibrium that is independent of a system’s displacements from its original position
static equilibrium: a state of equilibrium in which the net external force and torque acting on a system is zero

Chapter 10

Rotational Motion and Angular Momentum

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Summary

The kinematics of rotational motion describes the relationships among rotation angle, angular velocity, angular acceleration, and time Linear or tangential acceleration refers to changes in the magnitude of velocity but not its direction, given as a t = Δ v Δ t The radius r is constant for circular motion, and so Δ rω = r Δ ω .

Key terms

angular momentum: the product of moment of inertia and angular velocity
kinematics of rotational motion: describes the relationships among rotation angle, angular velocity, angular acceleration, and time
tangential acceleration: the acceleration in a direction tangent to the circle at the point of interest in circular motion
radius r: constant for circular motion, and so Δ rω = r Δ ω
angular acceleration: the rate of change of angular velocity with time
moment of inertia: mass times the square of perpendicular distance from the rotation axis; for a point mass, it is I = mr 2 and, because any object can be built up from a collection of point…
work-energy theorem: if one or more external forces act upon a rigid object, causing its kinetic energy to change from KE 1 to KE 2 , then the work W done by the net force is equal to the change in…

Chapter 11

Fluid Statics

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Summary

Fluid statics is the physics of stationary fluids The SI unit of pressure is pascal and 1 Pa = 1 N/m 2 Pressure is the weight of the fluid mg divided by the area A supporting it (the area of the bottom of the container): P = mg A A fluid is a state of matter that yields to sideways or shearing forces.

Key terms

fluid: a state of matter that yields to sideways or shearing forces
fluids: liquids and gases; a fluid is a state of matter that yields to shearing forces
pressure: the force per unit area perpendicular to the force, over which the force acts
density: the mass per unit volume of a substance or object
SI unit of pressure: pascal and 1 Pa = 1 N/m 2
Pascal’s Principle: a change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container
surface tension: the cohesive forces between molecules which cause the surface of a liquid to contract to the smallest possible surface area
micturition reflex: stimulates the feeling of needing to urinate, triggered by bladder pressure

Chapter 12

Fluid Dynamics and Its Biological and Medical Applications

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Summary

Flow rate and velocity are related by Q = A v ¯ where A is the cross-sectional area of the flow and v ¯ is its average velocity Flow rate Q is defined to be the volume V flowing past a point in time t , or Q = V t where V is volume and t is time Another common unit is the liter (L), which is 10 - 3 m 3 For incompressible fluids, flow rate at various points is constant.

Key terms

fluid dynamics: the physics of fluids in motion
flow rate: abbreviated Q , it is the volume V that flows past a particular point during a time t , or Q = V/t
v ¯ where A: the cross-sectional area of the flow and v ¯ is its average velocity
Bernoulli’s equation: the equation resulting from applying conservation of energy to an incompressible frictionless fluid: P + 1/2 pv 2 + pgh = constant , through the fluid
liter: a unit of volume, equal to 10 -3 m 3
terminal speed: the speed at which the viscous drag of an object falling in a viscous fluid is equal to the other forces acting on the object (such as gravity), so that the acceleration of the…
reverse dialysis: the process that occurs when back pressure is sufficient to reverse the normal direction of dialysis through membranes
reverse osmosis: the process that occurs when back pressure is sufficient to reverse the normal direction of osmosis through membranes

Chapter 13

Temperature, Kinetic Theory, and the Gas Laws

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Summary

Absolute zero is the temperature at which there is no molecular motion Temperature is related to the average kinetic energy of atoms and molecules in a system Systems are in thermal equilibrium when they have the same temperature The zeroth law of thermodynamics states that when two systems, A and B, are in thermal equilibrium with each other, and B is in thermal equilibrium with a third system, C, then A is also in thermal equilibrium with C

Key terms

temperature: the quantity measured by a thermometer
thermal equilibrium: the condition in which heat no longer flows between two objects that are in contact; the two objects have the same temperature
zeroth law of thermodynamics: law that states that if two objects are in thermal equilibrium, and a third object is in thermal equilibrium with one of those objects, it is also in thermal equilibrium with the…
mole: the quantity of a substance whose mass (in grams) is equal to its molecular mass
absolute zero: the lowest possible temperature; the temperature at which all molecular motion ceases
Dalton’s law of partial pressures: the physical law that states that the total pressure of a gas is the sum of partial pressures of the component gases
dew point: the temperature at which relative humidity is 100%; the temperature at which water starts to condense out of the air

Chapter 14

Heat and Heat Transfer Methods

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Summary

Any energy unit can be used for heat transfer, and the most common are kilocalorie (kcal) and joule (J) The transfer of heat Q that leads to a change Δ T in the temperature of a body with mass m is Q = mc Δ T , where c is the specific heat of the material. This relationship can also be considered as the definition of specific heat Heat and work are the two distinct methods of energy transfer

Key terms

heat: the spontaneous transfer of energy due to a temperature difference
specific heat: the amount of heat necessary to change the temperature of 1.00 kg of a substance by 1.00 ºC
most common: kilocalorie (kcal) and joule (J)
kilocalorie: 1 kilocalorie = 1000 calories
greenhouse effect: warming of the Earth that is due to gases such as carbon dioxide and methane that absorb infrared radiation from the Earth’s surface and reradiate it in all directions, thus…
Stefan-Boltzmann law of radiation: Q t = σ e A T 4 , where σ is the Stefan-Boltzmann constant, A is the surface area of the object, T is the absolute temperature, and e is the emissivity
latent heat coefficient: a physical constant equal to the amount of heat transferred for every 1 kg of a substance during the change in phase of the substance

Chapter 15

Thermodynamics

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Summary

The first law of thermodynamics is given as Δ E int = Q - W , where Δ E int is the change in internal energy of a system, Q is the net heat transfer (the sum of all heat transfer into and out of the system), and W is… There are several simple processes, used by heat engines, that flow from the first law of thermodynamics. The internal energy E int of a system depends only on the state of the system and not how it reached that state Metabolism of living organisms, and photosynthesis of plants, are specialized types of heat transfer, doing work, and internal energy of systems

Key terms

first law of thermodynamics: states that the change in internal energy of a system equals the net heat transfer into the system minus the net work done by the system
internal energy: the sum of the kinetic and potential energies of a system’s atoms and molecules
adiabatic process: a process in which no heat transfer takes place
heat engine: a machine that uses heat transfer to do work
second law of thermodynamics: heat transfer flows from a hotter to a cooler object, never the reverse, and some heat energy in any process is lost to available work in a cyclical process
Otto cycle: a thermodynamic cycle, consisting of a pair of adiabatic processes and a pair of isochoric processes, that converts heat into work, e.g., the four-stroke engine cycle of intake…
reversible process: a process in which both the heat engine system and the external environment theoretically can be returned to their original states

Chapter 16

Oscillatory Motion and Waves

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Summary

The simplest type of oscillations and waves are related to systems that can be described by Hooke’s law: F = - kx , where F is the restoring force, x is the displacement from equilibrium or deformation, and k is the… Periodic motion is a repetitious oscillation An oscillation is a back and forth motion of an object between two points of deformation An oscillation may create a wave, which is a disturbance that propagates from where it was created

Key terms

wave: a disturbance that moves from its source and carries energy
elastic potential energy: potential energy stored as a result of deformation of an elastic object, such as the stretching of a spring
oscillation: a back and forth motion of an object between two points of deformation
restoring force: force acting in opposition to the force caused by a deformation
periodic motion: motion that repeats itself at regular time intervals
period: time it takes to complete one oscillation
frequency: number of events per unit of time
deformation: displacement from equilibrium

Chapter 17

Physics of Hearing

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Summary

The intensity of a sound wave is also related to the pressure amplitude Δ p I = ( Δ p ) 2 ρv w , where ρ is the density of the medium in which the sound wave travels and v w is the speed of sound in the medium Sound is a disturbance of matter that is transmitted from its source outward The relationship of the speed of sound v w , its frequency f , and its wavelength λ is given by In air, the speed of sound is related to air temperature T by

Key terms

intensity of a sound wave: also related to the pressure amplitude Δ p I = ( Δ p ) 2 ρv w , where ρ is the density of the medium in which the sound wave travels and v w is the speed of sound in the
sound: a disturbance of matter that is transmitted from its source outward
intensity: the power per unit area carried by a wave
speed of sound: related to air temperature T by
intensity reflection coefficient: a measure of the ratio of the intensity of the wave reflected off a boundary between two media relative to the intensity of the incident wave

Chapter 18

Electric Charge and Electric Field

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Summary

The electric charge of one electron is equal in magnitude and opposite in sign to the charge of one proton An ion is an atom or molecule that has nonzero total charge due to having unequal numbers of electrons and protons The SI unit for charge is the coulomb (C), with protons and electrons having charges of opposite sign but equal magnitude; the magnitude of this basic charge ∣ q e ∣ is ∣ q e ∣ = 1.60 × 10 - 19 C The vast majority of positive charge in nature is carried by protons, while the vast majority of negative charge is carried by electrons

Key terms

electric charge: a physical property of an object that causes it to be attracted toward or repelled from another charged object; each charged object generates and is influenced by a force called…
field: a map of the amount and direction of a force acting on other objects, extending out into space
electric field: a three-dimensional map of the electric force extended out into space from a point charge
SI unit for charge: the coulomb (C), with protons and electrons having charges of opposite sign but equal magnitude; the magnitude of this basic charge ∣ q e ∣ is ∣ q e ∣ = 1.60 × 10 - 19 C
proton: a particle in the nucleus of an atom and carrying a positive charge equal in magnitude and opposite in sign to the amount of negative charge carried by an electron
ion: an atom or molecule that has nonzero total charge due to having unequal numbers of electrons and protons
electron: a particle orbiting the nucleus of an atom and carrying the smallest unit of negative charge
electric charge of one electron: equal in magnitude and opposite in sign to the charge of one proton

Chapter 19

Electric Potential and Electric Field

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Summary

Electric potential is potential energy per unit charge An electron volt is the energy given to a fundamental charge accelerated through a potential difference of 1 V. Mechanical energy is the sum of the kinetic energy and potential energy of a system, that is, KE + PE . The potential difference between points A and B, V B - V A , defined to be the change in potential energy of a charge q moved from A to B, is equal to the change in potential energy divided by the charge, Potential…

Key terms

electric potential: potential energy per unit charge
mechanical energy: sum of the kinetic energy and potential energy of a system; this sum is a constant
electron volt: the energy given to a fundamental charge accelerated through a potential difference of one volt
potential difference (or voltage): change in potential energy of a charge moved from one point to another, divided by the charge; units of potential difference are joules per coulomb, known as volt
equipotential line: a line along which the electric potential is constant
defibrillator: a machine used to provide an electrical shock to a heart attack victim's heart in order to restore the heart's normal rhythmic pattern
dielectric strength: the maximum electric field above which an insulating material begins to break down and conduct
grounding: fixing a conductor at zero volts by connecting it to the earth or ground

Chapter 20

Electric Current, Resistance, and Ohm's Law

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Summary

The SI unit for current is the ampere (A), where 1 A = 1 C/s Electric current I is the rate at which charge flows, given by I = Δ Q Δ t , where Δ Q is the amount of charge passing through an area in time Δ t The direction of conventional current is taken as the direction in which positive charge moves Drift velocity v d is the average speed at which these charges move

Key terms

resistance: the electric property that impedes current; for ohmic materials, it is the ratio of voltage to current, R = V/I
electric current: the rate at which charge flows, I = Δ Q /Δ t
ohm: the unit of resistance, given by 1Ω = 1 V/A
drift velocity: the average velocity at which free charges flow in response to an electric field
direction of conventional current: taken as the direction in which positive charge moves
ampere: (amp) the SI unit for current; 1 A = 1 C/s
SI unit for current: the ampere (A), where 1 A = 1 C/s
AC current: current that fluctuates sinusoidally with time, expressed as I = I 0 sin 2 πft , where I is the current at time t, I 0 is the peak current, and f is the frequency in hertz

Chapter 21

Circuits and DC Instruments

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Summary

The voltage drop, or power dissipation, across each individual resistor in a series is different, and their combined total adds up to the power source input If a more complex connection of resistors is a combination of series and parallel, it can be reduced to a single equivalent resistance by identifying its various parts as series or parallel, reducing each to its… Each resistor in a series circuit has the same amount of current flowing through it Each resistor in a parallel circuit has the same full voltage of the source applied to it

Key terms

electromotive force (emf): the potential difference of a source of electricity when no current is flowing; measured in volts
parallel: the wiring of resistors or other components in an electrical circuit such that each component receives an equal voltage from the power source; often pictured in a ladder-shaped…
more complex connection of resistors: a combination of series and parallel, it can be reduced to a single equivalent resistance by identifying its various parts as series or parallel, reducing each to its…
voltage: the electrical potential energy per unit charge; electric pressure created by a power source, such as a battery
voltage drop: the loss of electrical power as a current travels through a resistor, wire or other component
resistor: a component that provides resistance to the current flowing through an electrical circuit
series: a sequence of resistors or other components wired into a circuit one after the other
current: the flow of charge through an electric circuit past a given point of measurement

Chapter 22

Magnetism

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Summary

The atoms in ferromagnetic materials act like small magnets (due to currents within the atoms) and can be aligned, usually in millimeter-sized regions called domains Magnetism is a subject that includes the properties of magnets, the effect of the magnetic force on moving charges and currents, and the creation of magnetic fields by currents There are two types of magnetic poles, called the north magnetic pole and south magnetic pole North magnetic poles are those that are attracted toward the Earth’s geographic north pole

Key terms

meter: common application of magnetic torque on a current-carrying loop that is very similar in construction to a motor; by design, the torque is proportional to I and not θ , so the…
north magnetic pole: the end or the side of a magnet that is attracted toward Earth’s geographic north pole
south magnetic pole: the end or the side of a magnet that is attracted toward Earth’s geographic south pole
ferromagnetic: materials, such as iron, cobalt, nickel, and gadolinium, that exhibit strong magnetic effects
magnetic force: the force on a charge produced by its motion through a magnetic field; the Lorentz force
domains: regions within a material that behave like small bar magnets
magnetic field: the representation of magnetic forces
Ampere’s law: the physical law that states that the magnetic field around an electric current is proportional to the current; each segment of current produces a magnetic field like that of a…

Chapter 23

Electromagnetic Induction, AC Circuits, and Electrical Technologies

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Summary

The crucial quantity in induction is magnetic flux Φ , defined to be Φ = BA cos θ , where B is the magnetic field strength over an area A at an angle θ with the perpendicular to the area Any change in magnetic flux Φ induces an emf—the process is defined to be electromagnetic induction Faraday’s law of induction states that the emfinduced by a change in magnetic flux is emf = - N Δ Φ Δ t when flux changes by Δ Φ in a time Δ t The minus sign means that the emf creates a current I and magnetic field B that oppose the change in flux Δ Φ —this opposition is known as Lenz’s law

Key terms

induction: (magnetic induction) the creation of emfs and hence currents by magnetic fields
electromagnetic induction: the process of inducing an emf (voltage) with a change in magnetic flux
magnetic flux: the amount of magnetic field going through a particular area, calculated with Φ = BA cos θ where B is the magnetic field strength over an area A at an angle θ with the…
crucial quantity in induction: magnetic flux Φ , defined to be Φ = BA cos θ , where B is the magnetic field strength over an area A at an angle θ with the perpendicular to the area
magnetic field B: called a motional emf and is given by emf = Bℓv ( B , ℓ , and v perpendicular), where ℓ is the length of the object moving at speed v relative to the field
Faraday’s law of induction: the means of calculating the emf in a coil due to changing magnetic flux, given by emf = - N ΔΦ Δt
Lenz’s law: the minus sign in Faraday’s law, signifying that the emf induced in a coil opposes the change in magnetic flux
eddy current: a current loop in a conductor caused by motional emf

Chapter 24

Electromagnetic Waves

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Summary

Electromagnetic waves consist of oscillating electric and magnetic fields and propagate at the speed of light c . Since the electric and magnetic fields in most electromagnetic waves are perpendicular to the direction in which the wave moves, it is ordinarily a transverse wave Maxwell’s prediction of electromagnetic waves resulted from his formulation of a complete and symmetric theory of electricity and magnetism, known as Maxwell’s equations Electromagnetic waves are created by oscillating charges (which radiate whenever accelerated) and have the same frequency as the oscillation

Key terms

electromagnetic waves: radiation in the form of waves of electric and magnetic energy
speed of light: in a vacuum, such as space, the speed of light is a constant 3 x 10 8 m/s
electric field: a vector quantity ( E ); the lines of electric force per unit charge, moving radially outward from a positive charge and in toward a negative charge
transverse wave: a wave, such as an electromagnetic wave, which oscillates perpendicular to the axis along the line of travel
frequency: the number of complete wave cycles (up-down-up) passing a given point within one second (cycles/second)
magnetic field: a vector quantity ( B ); can be used to determine the magnetic force on a moving charged particle
Maxwell’s equations: a set of four equations that comprise a complete, overarching theory of electromagnetism
radio waves: electromagnetic waves with wavelengths in the range from 1 mm to 100 km; they are produced by currents in wires and circuits and by astronomical phenomena

Chapter 25

Geometric Optics

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Summary

The part of optics dealing with the ray aspect of light is called geometric optics The changing of a light ray’s direction when it passes through variations in matter is called refraction A straight line that originates at some point is called a ray Light can travel in three ways from a source to another location: (1) directly from the source through empty space; (2) through various media; (3) after being reflected from a mirror

Key terms

geometric optics: part of optics dealing with the ray aspect of light
mirror: smooth surface that reflects light at specific angles, forming an image of the person or object in front of it
refraction: changing of a light ray’s direction when it passes through variations in matter
ray: straight line that originates at some point
corner reflector: an object consisting of two mutually perpendicular reflecting surfaces, so that the light that enters is reflected back exactly parallel to the direction from which it came
rainbow: dispersion of sunlight into a continuous distribution of colors according to wavelength, produced by the refraction and reflection of sunlight by water droplets in the sky

Chapter 26

Vision and Optical Instruments

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Summary

In myopia and hyperopia, the corrective lenses produce images at a distance that the person can see clearly—the far point and near point, respectively The eye produces a real image on the retina by adjusting its focal length and power in a process called accommodation Nearsightedness, or myopia, is the inability to see distant objects and is corrected with a diverging lens to reduce power Farsightedness, or hyperopia, is the inability to see close objects and is corrected with a converging lens to increase power

Key terms

myopia: a visual defect in which distant objects appear blurred because their images are focused in front of the retina rather than being focused on the retina
nearsightedness: another term for myopia, a visual defect in which distant objects appear blurred because their images are focused in front of the retina rather than being focused on the retina
near point: the point nearest the eye at which an object is accurately focused on the retina at full accommodation
accommodation: the ability of the eye to adjust its focal length is known as accommodation
farsightedness: another term for hyperopia, the condition of an eye where incoming rays of light reach the retina before they converge into a focused image
hyperopia: the condition of an eye where incoming rays of light reach the retina before they converge into a focused image
presbyopia: a condition in which the lens of the eye becomes progressively unable to focus on objects close to the viewer
eye: adequately described by the thin lens equations: P = 1 d o + 1 d i and h i h o = - d i d o = m

Chapter 27

Wave Optics

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Summary

An accurate technique for determining how and where waves propagate is given by Huygens’s principle: Every point on a wavefront is a source of wavelets that spread out in the forward direction at the same speed as the… The new wavefront is a line tangent to all of the wavelets Wave characteristics are those associated with interference and diffraction Like all EM waves, the following relationship is valid in vacuum: c = f λ , where c = 3 × 10 8 m/s is the speed of light, f is the frequency of the electromagnetic wave, and λ is its wavelength in vacuum

Key terms

Huygens’s principle: every point on a wavefront is a source of wavelets that spread out in the forward direction at the same speed as the wave itself. The new wavefront is a line tangent to all of…
following relationship: valid in vacuum: c = f λ , where c = 3 × 10 8 m/s is the speed of light, f is the frequency of the electromagnetic wave, and λ is its wavelength in vacuum
wavefront: a source of wavelets that spread out in the forward direction at the same speed as the…
diffraction: the bending of a wave around the edges of an opening or an obstacle
new wavefront: a line tangent to all of the wavelets
Brewster’s angle: θ b = tan - 1 n 2 n 1 , where n 2 is the index of refraction of the medium from which the light is reflected and n 1 is the index of refraction of the medium in which the…
Brewster’s law: tan θ b = n 2 n 1 , where n 1 is the medium in which the incident and reflected light travel and n 2 is the index of refraction of the medium that forms the interface that…

Chapter 28

Special Relativity

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Summary

The first postulate of special relativity is the idea that the laws of physics are the same and can be stated in their simplest form in all inertial frames of reference. The second postulate of special relativity is the idea that the speed of light c is a constant, independent of the relative motion of the source Special relativity deals with observers who are in uniform (unaccelerated) motion, whereas general relativity includes accelerated relative motion and gravity. Relativity is the study of how different observers measure the same event

Key terms

special relativity: the theory that, in an inertial frame of reference, the motion of an object is relative to the frame from which it is viewed or measured
relativity: the study of how different observers measure the same event
first postulate of special relativity: the idea that the laws of physics are the same and can be stated in their simplest form in all inertial frames of reference
second postulate of special relativity: the idea that the speed of light c is a constant, independent of the source
inertial frame of reference: a reference frame in which a body at rest remains at rest and a body in motion moves at a constant speed in a straight line unless acted on by an outside force
classical velocity addition: the method of adding velocities when v << c ; velocities add like regular numbers in one-dimensional motion: u = v + u ′ , where v is the velocity between two observers, u is the…
Michelson-Morley experiment: an investigation performed in 1887 that proved that the speed of light in a vacuum is the same in all frames of reference from which it is viewed
proper length: L 0 ; the distance between two points measured by an observer who is at rest relative to both of the points; Earth-bound observers measure proper length when measuring the…

Chapter 29

Quantum Physics

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Summary

The first indication that energy is sometimes quantized came from blackbody radiation, which is the emission of EM radiation by an object with an emissivity of 1 Another indication of energy levels being quantized in atoms and molecules comes from the lines in atomic spectra, which are the EM emissions of individual atoms and molecules Planck recognized that the energy levels of the emitting atoms and molecules were quantized, with only the allowed values of E = n + 1 2 hf , where n is any non-negative integer (0, 1, 2, 3, …) H is Planck’s constant, whose value is h = 6 .

Key terms

photoelectric effect: the phenomenon whereby some materials eject electrons when light is shined on them
quantized: the fact that certain physical entities exist only with particular discrete values and not every conceivable value
blackbody: an ideal radiator, which can radiate equally well at all wavelengths
atomic spectra: the electromagnetic emission from atoms and molecules
photon: a quantum, or particle, of electromagnetic radiation
blackbody radiation: the electromagnetic radiation from a blackbody
Planck’s constant: h = 6 . 626 × 10 -34 J ⋅ s

Chapter 30

Atomic Physics

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Summary

The first direct observation of atoms was in Brownian motion Analysis of Brownian motion gave accurate sizes for atoms ( 10 -10 m on average) and a precise value for Avogadro’s number The planetary model of the atom pictures electrons orbiting the nucleus in the same way that planets orbit the sun The planetary model of the atom pictures electrons orbiting the nucleus in the way that planets orbit the sun.

Key terms

atom: basic unit of matter, which consists of a central, positively charged nucleus surrounded by negatively charged electrons
positive charge in the nuclei: carried by particles called protons, which have a charge-to-mass ratio of q p m p = 9
Brownian motion: the continuous random movement of particles of matter suspended in a liquid or gas
planetary model of the atom: the most familiar model or illustration of the structure of the atom
Pauli exclusion principle: a principle that states that no two electrons can have the same set of quantum numbers; that is, no two electrons can be in the same state
stimulated emission: emission by atom or molecule in which an excited state is stimulated to decay, most readily caused by a photon of the same energy that is necessary to excite the state
fine structure: the splitting of spectral lines of the hydrogen spectrum when the spectral lines are examined at very high resolution
hologram: means entire picture (from the Greek word holo , as in holistic), because the image produced is three dimensional

Chapter 31

Radioactivity and Nuclear Physics

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Summary

Some nuclei are radioactive—they spontaneously decay destroying some part of their mass and emitting energetic rays, a process called nuclear radioactivity Nuclear radiation, like x rays, is ionizing radiation, because energy sufficient to ionize matter is emitted in each decay The range (or distance traveled in a material) of ionizing radiation is directly related to the charge of the emitted particle and its energy, with greater-charge and lower-energy particles having the shortest ranges The two types of nucleons are protons and neutrons; they are very similar, except that the proton is positively charged while the neutron is neutral.

Key terms

radioactivity: the emission of rays from the nuclei of atoms
activity: the rate of decay for radioactive nuclides
two types of nucleons: protons and neutrons; they are very similar, except that the proton is positively charged while the neutron is neutral
radiation detector: a device that is used to detect and track the radiation from a radioactive reaction
neutron: a neutral particle that is found in a nucleus
material) of ionizing radiation: directly related to the charge of the emitted particle and its energy, with greater-charge and lower-energy particles having the shortest ranges
decay: the process by which an atomic nucleus of an unstable atom loses mass and energy by emitting ionizing particles
ionizing radiation: radiation (whether nuclear in origin or not) that produces ionization whether nuclear in origin or not

Chapter 32

Medical Applications of Nuclear Physics

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Summary

Radiopharmaceuticals are compounds that are used for medical imaging and therapeutics Table 32.1 lists certain diagnostic uses of radiopharmaceuticals including the isotope and activity typically used in diagnostics One common imaging device is the Anger camera, which consists of a lead collimator, radiation detectors, and an analysis computer Tomography performed with γ -emitting radiopharmaceuticals is called SPECT and has the advantages of x-ray CT scans coupled with organ- and function-specific drugs

Key terms

biological effects of ionizing radiation: due to two effects it has on cells: interference with cell reproduction, and destruction of cell function
Anger camera: a common medical imaging device that uses a scintillator connected to a series of photomultipliers
rad: the ionizing energy deposited per kilogram of tissue
radiopharmaceutical: compound used for medical imaging
magnetic confinement: a technique in which charged particles are trapped in a small region because of difficulty in crossing magnetic field lines
ignition: when a fusion reaction produces enough energy to be self-sustaining after external energy input is cut off
nuclear fusion: a reaction in which two nuclei are combined, or fused, to form a larger nucleus
gray (Gy): the SI unit for radiation dose which is defined to be 1 Gy = 1 J/kg = 100 rad

Chapter 33

Particle Physics

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Summary

Modern accelerators used in particle physics are either large synchrotrons or linear accelerators Yukawa’s idea of virtual particle exchange as the carrier of forces is crucial, with virtual particles being formed in temporary violation of the conservation of mass-energy as allowed by the Heisenberg uncertainty… Feynman diagrams are graphs of time versus position and are highly useful pictorial representations of particle processes The theory of electromagnetism on the particle scale is called quantum electrodynamics (QED)

Key terms

particle physics: the study of and the quest for those truly fundamental particles having no substructure
synchrotron: a version of a cyclotron in which the frequency of the alternating voltage and the magnetic field strength are increased as the beam particles are accelerated
carrier of forces: crucial, with virtual particles being formed in temporary violation of the conservation of mass-energy as allowed by the Heisenberg uncertainty…
Feynman diagram: a graph of time versus position that describes the exchange of virtual particles between subatomic particles
virtual particles: particles which cannot be directly observed but their effects can be directly observed
colliding beams: head-on collisions between particles moving in opposite directions
linear accelerator: accelerator that accelerates particles in a straight line
quantum electrodynamics: the theory of electromagnetism on the particle scale

Chapter 34

Frontiers of Physics

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Summary

The earliest epochs are tied to the unification of forces, with the electroweak epoch being partially understood, the GUT epoch being speculative, and the TOE epoch being highly speculative since it involves an unknown… The epochs of the universe are known back to very shortly after the Big Bang, based on known laws of physics The two most important features of the universe are the cosmological red shifts of its galaxies being proportional to distance and its cosmic microwave background (CMBR). Both support the notion that there was a gigantic explosion, known as the Big Bang that created the universe

Key terms

GUT epoch: the time period from 10 -43 to 10 -34 after the Big Bang, when Grand Unification Theory, in which all forces except gravity are identical, governed the universe
Hubble constant: a central concept in cosmology whose value is determined by taking the slope of a graph of velocity versus distance, obtained from red shift measurements
cosmological red shift: the photon wavelength is stretched in transit from the source to the observer because of the expansion of space itself
smoothness of the CMBR: two characteristics that are tied to particle physics
earliest epochs: tied to the unification of forces, with the electroweak epoch being partially understood, the GUT epoch being speculative, and the TOE epoch being highly speculative sinc
epochs of the universe: known back to very shortly after the Big Bang, based on known laws of physics
Big Bang: a gigantic explosion that threw out matter a few billion years ago
electroweak epoch: the stage before 10 -11 back to 10 -34 after the Big Bang