Glossary
A
>
air resistance (F air) the friction between objects and the
air around them (p. 63)
air wedge the air between two sheets of flat glass angled
to form a wedge (p. 508)
amplitude (A) the maximum displacement of a wave
(p. 197)
analyzer a second polarizer used to verify that the light
from the first polarizer is polarized (p. 534)
angle of deviation the angle between the incident ray and
the final outgoing ray after reflection or refraction
(p. 451)
angle of incidence the angle between the incident ray and
the normal (p. 442)
angle of reflection the angle between the reflected ray and
the normal (p. 442)
angle of refraction the angle that a light ray makes with
respect to the normal to the surface when it has
entered a different medium (p. 446)
antimatter a form of matter in which each particle has the
same mass and an opposite charge as its counterpart
in ordinary matter (p. 647)
apparent weight the magnitude of the normal force acting
on an object in an accelerated (non-inertial) frame of
reference (p. 111)
>
applied force (F a) a force due to one object pushing or
pulling on another (p. 63)
artificial gravity a situation in which the value of gravity
has been changed artificially to more closely match
Earth’s gravity (p. 128)
artificial satellite an object that has been intentionally
placed by humans into orbit around Earth or another
body; referred to as “artificial” to distinguish from
natural satellites such as the Moon (p. 297)
>
average acceleration (aav) the change in velocity divided
by the time interval for that change (p. 14)
average speed (vav) the total distance travelled divided by
the total time to travel that distance (p. 9)
>
average velocity (vav) the displacement divided by the
time interval for that change; the slope of a secant
on a position–time graph (p. 9)
B
biochemical energy a type of chemical potential energy
stored in the cells and other basic structures of
biological organisms (p. 188)
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8160_Glossary_p725-731.indd 725
blackbody an object that absorbs all radiation reaching it
(p. 626)
blackbody radiation radiation emitted by an ideal
blackbody (p. 626)
boson the particle responsible for transmitting
electromagnetic, strong, and weak forces (p. 651)
Brewster’s angle the angle at which the direction of the
reflected portion of the wave is perpendicular to the
direction of the refracted portion of the wave (p. 535)
n2
Brewster’s law tan u B 5
(p. 535)
n1
C
central maximum the bright central region in the
interference pattern of light and dark lines produced
in diffraction (p. 512)
centrifugal force the fictitious force in a rotating
(accelerating or non-inertial) frame of reference
(p. 126)
centrifuge a rapidly rotating device used to separate
substances and simulate the effects of gravity (p. 125)
>
centripetal acceleration (ac) the instantaneous
acceleration that is directed toward the centre of
a circular path (p. 114)
centripetal force (Fc) the net force that causes centripetal
acceleration (p. 121)
coefficient of kinetic friction (μK) the ratio of kinetic
friction to the normal force (p. 85)
coefficient of static friction (μS) the ratio of the maximum
force of static friction to the normal force (p. 86)
coherent composed of waves having the same frequency
and fixed phases (p. 462)
collision the impact of one body with another (p. 228)
component of a vector in two dimensions, either of the
x-vector and y-vector that are combined into an
overall vector (p. 25)
Compton effect the elastic scattering of photons by highenergy photons (p. 624)
conductor any substance in which electrons are able to
move easily from one atom to another (p. 321)
conservation of kinetic energy the total kinetic energy
of two objects before a collision is equal to the total
kinetic energy of the two objects after the collision
(p. 233)
conservation of mass–energy the principle that rest mass
and energy are equivalent (p. 599)
Glossary 725
4/26/12 8:00 AM
constructive interference the phenomenon that occurs
when two interfering waves have displacement in the
same direction where they superimpose (p. 462)
contact force a force that acts between two objects when
they touch each other (p. 62)
Coriolis force a fictitious force that acts perpendicular
to the velocity of an object in a rotating frame of
reference (p. 127)
coulomb the SI unit of electric charge; symbol C (p. 321)
Coulomb’s constant (k) the proportionality constant in
Coulomb’s law; k 5 8.99 3 109 N?m2/C2 (p. 327)
Coulomb’s law the force between two point charges is
inversely proportional to the square of the distance
between the charges and directly proportional to the
product of the charges (p. 327)
crest the upper part of a wave (p. 441)
critical angle the smallest angle of incidence at which a
light ray passing from one medium to another less
refractive medium can be totally reflected from the
boundary between the two (p. 453)
D
damped harmonic motion periodic motion affected by
friction (p. 207)
de Broglie wavelength the wavelength associated with
the motion of a particle possessing momentum of
magnitude p (p. 632)
destructive interference the phenomenon that occurs
when two interfering waves have displacement in
opposite directions where they superimpose (p. 462)
diffraction the bending and spreading of a wave when it
passes through an opening; dependent on the size of
the opening and the wavelength of the wave (p. 459)
diffraction grating a device with a large number of equally
spaced parallel slits that produces interference patterns
(p. 520)
diffuse reflection the reflection of light from a surface
where all the reflected rays are directed in many
different directions (p. 442)
dispersion the separation of a wave into its component
parts according to a given characteristic, such as
frequency or >wavelength (p. 450)
displacement (Dd ) the change in position of an object (p. 8)
dynamics the study of the causes of motion (p. 8)
E
elastic collision a collision in which momentum and
kinetic energy are conserved (p. 233)
elastic potential energy the potential energy due to the
electric dipole a pair of equal and opposite electric charges
with centres separated by a small distance (p. 339)
>
electric field (e ) the region in which a force is exerted on
an electric charge; the electric force per unit positive
charge; unit is N/C (p. 334)
electric field lines the continuous lines of force around
charges that show the direction of the electric force
at all points in the electric field (p. 338)
electric force (FE) a force with magnitude and direction
that acts between two charged particles (p. 327)
electric potential (V) the value, in volts, of potential
energy per unit positive charge for a given point
in an electric field; 1 V 5 1 J/C (p. 350)
electric potential difference (DV) the amount of work
required per unit charge to move a positive charge
from one point to another in the presence of an
electric field (p. 350)
electric potential due to a point charge the electric
potential is inversely proportional to the distance from
the charge and proportional to the amount of charge
producing the field (p. 355)
electric potential energy (EE) the energy stored in a
system of two charges a distance Δd apart, or the
energy stored in an electric field that can do work
on a positively charged particle (p. 347)
electromagnetic radiation radiation that consists of
interacting electric and magnetic fields that travel at
the speed of light (p. 526)
electromagnetic spectrum the range of frequencies and
wavelengths of all electromagnetic waves (p. 527)
elementary charge (e) the magnitude of the electric charge
carried by a proton, equal to the absolute value of the
electric charge of an electron (p. 362)
equilibrium a state in which an object has no net force
acting on it (p. 77)
ether the proposed medium through which electromagnetic
waves were once believed to propagate (p. 576)
explosion a situation in which a single object or group of
objects breaks apart (p. 229)
F
fermion a fundamental particle that forms matter (p. 651)
fibre optics a technology that uses glass or plastic wire
(fibre) through which data are transmitted using
internally reflected light impulses (p. 455)
fictitious force an apparent but non-existent force invented
to explain the motion of objects within an accelerating
(non-inertial) frame of reference (p. 109)
stretching or compressing of an elastic material (p. 195)
726 Glossary
8160_Glossary_p725-731.indd 726
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field theory a scientific model that describes forces
in terms of entities that exist at every point in
space (p. 403)
first-order maximum the first maximum of intensity
on either side of the zero-order maximum in an
interference pattern from a diffraction grating (p. 521)
>
force (F ) a push or a pull (p. 62)
>
force of gravity (F g) the force of attraction between all
objects due to mass (p. 62)
frame of reference a coordinate system relative to which
motion is described or observed (pp. 44, 108, 575)
Fraunhofer diffraction an interference pattern that shows
distinctive differences between the bright central
fringe and darker flanking fringes (p. 512)
free-body diagram a simple line drawing that shows all the
forces acting on an object (p. 63)
free fall the motion of a falling object where the only force
acting on the object is gravity (p. 20)
frequency (f ) the number of rotations, revolutions, or
vibrations of an object per unit of time; the inverse of
period; SI unit Hz (p. 117)
>
friction (F f ) a force that opposes the sliding of two surfaces
across one another; acts opposite to motion or
attempted motion (p. 63)
fundamental physical constant a measurable natural
value that never varies and can be determined by
experimentation (p. 362)
G
geosynchronous orbit the orbit around Earth of an object
with an orbital speed matching the rate of Earth’s
rotation; the period of such an orbit is exactly one
Earth day (p. 300)
glancing collision a collision in which the first object, after
an impact with the second object, travels at an angle to
the direction it was originally travelling (p. 250)
gluon a particle that mediates the strong nuclear force
(p. 651)
gravitational constant a constant that appears in the
universal law of gravitation; the constant is written as
G and has a value of 6.67 3 10211 N?m2/kg2 (p. 288)
gravitational field a collection of vectors, one at each point
in space, that determines the magnitude and direction
of the gravitational force (p. 293)
gravitational field strength the magnitude of the
gravitational field vector at a point in space (p. 293)
gravitational potential energy (Eg) stored energy an
object has because of its position and the applied
gravitational force (p. 177)
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8160_Glossary_p725-731.indd 727
H
hadrons a class of particles that contains the neutron, the
proton, and the pion; composed of combinations of
quarks and anti-quarks (p. 648)
head-on elastic collision an impact in which two objects
approach each other from opposite directions;
momentum and kinetic energy are conserved after
the collision (p. 240)
Heisenberg uncertainty principle a mathematical
statement that says that if Dx is the uncertainty in
a particle’s position, and Dp is the uncertainty in its
h
momentum, then DxDp $
, where h is Planck’s
4p
constant (p. 637)
Higgs boson the theoretical particle thought to play a role
in giving mass to other particles (p. 652)
Hooke’s law the amount of force exerted by a spring is
directly proportional to the displacement of the
spring (p. 192)
Huygens’ principle every point on a wave front can
be considered as a point source of tiny secondary
wavelets that spread out in front of the wave at the
same speed as the wave itself (p. 470)
I
ideal spring any spring that obeys Hooke’s law; it does not
experience any internal or external friction (p. 193)
impulse the product of force and time that acts on an
object to produce a change in momentum (p. 223)
incoherent composed of waves that have no fixed phase
relationship to each other and different frequencies
(p. 477)
index of refraction the ratio of the speed of light in a vacuum
to the speed of light in another medium (p. 444)
inelastic collision a collision in which momentum is
conserved, but kinetic energy is not conserved (p. 234)
inertia a measure of an object’s resistance to change in
velocity (p. 70)
inertial frame of reference a frame of reference that moves
at a zero or constant velocity; a frame in which the law
of inertia holds (pp. 108, 575)
>
instantaneous acceleration (a ) the acceleration at a
particular instant in time (p. 14)
instantaneous speed (v) the speed of an object at a
particular instant; the magnitude of the slope of the
tangent to a position–time graph (p. 12)
>
instantaneous velocity (v ) the velocity of an object at
a particular instant; the slope of the tangent to a
position–time graph (p. 12)
Glossary 727
4/26/12 8:00 AM
insulator any substance in which electrons are not free to
move easily from one atom to another (p. 321)
interference the phenomenon that occurs when two waves
in the same medium interact (p. 462)
interference fringe one of a series of alternating light and
dark regions that result from the interference of waves
(p. 479)
inverse-square law a mathematical relationship in which
one variable is proportional to the inverse of the square
of another variable; the law applies to gravitational
forces and other phenomena, such as electric field
strength and sound intensity (p. 289)
isolated system a system that cannot interact or exchange
energy with external systems; also called a closed
system (p. 188)
J
muon, the tauon, and the three types of neutrinos; not
composed of smaller particles (p. 648)
linear actuator a device that converts energy into linear
motion (p. 91)
>
linear momentum (p ) a quantity that describes the motion
of an object travelling in a straight line as the product
of its mass and velocity (p. 222)
linearly polarized (plane polarized) the quality of light waves
that are polarized in one direction, perpendicular to
the direction of propagation (p. 532)
liquid crystal display (LCD) a thin, flat display that makes
use of polarizers and optical activity (p. 536)
M
magnetic field line one of a set of lines drawn to indicate
joule the SI unit of work and energy; a force of 1 N acting
over a displacement of 1 m does 1 J of work; symbol J
(p. 165)
K
kinematics the study of motion without considering the
forces that produce the motion (p. 8)
kinetic energy (Ek) the energy an object has because of its
motion (p. 171)
>
kinetic friction (F K) a force exerted on a moving object by
a surface in the direction of motion opposite to the
motion of the object (p. 63)
L
law of conservation of charge charge can be transferred
from one object to another, but the total charge of a
closed system remains constant (p. 321)
law of conservation of energy energy is neither created
nor destroyed in an isolated system; it can only change
form (pp. 184, 188)
law of conservation of momentum when two objects
collide in an isolated system, the collision does not
change the total momentum of the two objects;
whatever momentum is lost by one object in the
collision is gained by the other; the total momentum
of the system is conserved (p. 229)
law of electric charges like charges repel each other;
unlike charges attract (p. 320)
law of reflection for reflection from a flat surface, the angle
of incidence is always equal to the angle of reflection
(p. 442)
length contraction the shortening of length or distance in
an inertial frame of reference moving relative to an
observer in another inertial frame of reference (p. 589)
728
leptons a class of particles that includes the electron, the
Glossary
8160_Glossary_p725-731.indd 728
the strength and direction of a magnetic field (p. 378)
magnetic resonance imaging (MRI) a process in which
magnetic fields interact with atoms in the human
body, producing images that doctors can use to
diagnose injuries and diseases (p. 408)
magnetorheological fluid a fluid containing suspended
iron particles that, when subjected to a magnetic field,
changes to a solid (p. 406)
Malus’s law Iout 5 Iin cos 2 u (p. 533)
mass a measure of the amount of matter in an object (p. 71)
matter wave the wave-like behaviour of particles with
mass (p. 632)
maxima points of brightness, or maximum intensity,
in an interference pattern (p. 479)
mechanical energy the sum of an object’s kinetic and
potential energies (p. 177)
minima points of darkness, or minimum intensity, in an
interference pattern (p. 480)
monochromatic composed of only one colour; light with
one wavelength (p. 477)
N
>
net force (SF ) the sum of all the forces acting on an object
(p. 65)
newton the SI unit of force; symbol N (p. 62)
Newton’s first law of motion if the external net force on
an object is zero, the object will remain at rest or
continue to move at a constant velocity (p. 70)
Newton’s second law of motion if the net external force
on an object is not zero, the object will accelerate in
the direction of the net force; the magnitude of the
acceleration is directly proportional to the magnitude
of the net force and inversely proportional to the
object’s mass (p. 71)
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Newton’s third law of motion for every action force, there
exists a simultaneous reaction force that is equal in
magnitude but opposite in direction (p. 73)
nodal line a line or curve along which destructive
interference results in zero displacement (p. 463)
node a point along a standing wave where the wave
produces zero displacement (p. 463)
non-contact force a force that acts between two objects
without the objects touching; also called action-at-adistance force (p. 62)
non-inertial frame of reference a frame of reference that
accelerates with respect to an inertial frame; the law of
inertia does not hold (p. 108)
normal the line drawn at a right angle to the boundary at
the point where an incident ray strikes the boundary
(p. 442) >
normal force (F N) a force perpendicular to the surface
between objects in contact (p. 62)
O
open system a system that can interact with another
external system (p. 188)
optical activity the rotation of the direction of polarization
when linearly polarized light interacts with certain
molecules (p. 536)
optical density the property of a material that determines
how light behaves when it travels through the material
(p. 444)
orbital radius the distance between the centre of a satellite
and the centre of its parent body (p. 299)
order number the value of m for a given maximum in a
diffraction-grating interference pattern; sequentially
numbers the maxima on either side of the zero-order
maximum (p. 521)
P
pair creation the transformation of a photon into two
particles with mass (p. 626)
path length the distance from point to point along a nodal
line (p. 464)
path length difference the difference between path lengths,
or distances (p. 465)
perfectly elastic collision an ideal collision in which external
forces are minimized to the point where momentum
and kinetic energy are perfectly conserved (p. 235)
perfectly inelastic collision an ideal collision in which
two objects stick together perfectly so they have the
same final velocity; in this situation, momentum
is perfectly conserved, but kinetic energy is not
conserved (p. 235)
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8160_Glossary_p725-731.indd 729
period (T) the time required for a rotating, revolving,
or vibrating object to complete one cycle (p. 116)
periodic wave a wave with a repeated pattern over time
or distance (p. 440)
perpetual motion machine a machine that can operate
forever without restarting or refuelling (p. 205)
phase the offset of the wave from a reference point (p. 441)
photoelectric effect the phenomenon of electrons
being ejected from a material when exposed to
electromagnetic radiation (p. 621)
photon a discrete bundle of energy carried by light (p. 622)
Planck’s constant (h) a constant with the value
6.63 × 10–34 J?s; represents the ratio of the energy
of a single quantum to its frequency (p. 622)
polarized light light waves that vibrate in a single plane
(p. 532)
polarizer a device that allows only light with an electric
field along a single direction to pass through (p. 532)
>
position (d ) the straight-line distance and direction of an
object from a reference point (p. 8)
postulate a statement assumed to be true from which a
theory is developed (p. 577)
potential energy the stored energy an object has that can
be converted into another form of energy (p. 177)
power the rate of work done by a force over time, or the
rate at which the energy of an open system changes
(p. 189)
principle of electromagnetism moving electric charges
produce a magnetic field (p. 382)
principle of relativity the laws of motion are the same in all
inertial frames (p. 575)
principle of reversibility a light ray will follow exactly the
same path if its direction of travel is reversed (p. 444)
projectile an object that is launched through the air along
a parabolic trajectory and accelerates due to gravity
(p. 36)
projectile motion the motion of a projectile such that the
horizontal component of the velocity is constant, and
the vertical motion has a constant acceleration due to
gravity (p. 36)
proper length (Ls) the length of an object or distance
between two points as measured by an observer who
is stationary relative to the object or distance (p. 588)
proper time (Δts) the time interval measured by an
observer at rest with respect to a clock (p. 584)
Glossary 729
4/26/12 8:00 AM
Q
right-hand rule for a moving charge in a magnetic field
quantum the smallest amount of energy that a particle can
emit or absorb; the plural is quanta (p. 616)
quantum theory the theoretical basis of modern physics
that explains the nature and behaviour of matter and
energy at the atomic and subatomic levels (p. 616)
quark an elementary particle that makes up protons,
neutrons, and other hadrons (p. 648)
R
radio-frequency identification technology (RFID)
a technology that uses microchips that act as
transmitters and responders to communicate data
by radio waves (p. 405)
range (Δdx) the horizontal displacement of a projectile
(p. 36)
ray approximation treating the propagation of light
waves as though they move in straight lines called
rays (p. 442)
rectilinear propagation light travelling in straight lines
(p. 470)
reflection a change in direction of a light ray when it meets
an obstacle where the incoming ray and the outgoing
ray are on the same side of the obstacle (p. 442)
refraction the bending of light as it travels at an angle
from one medium to another (p. 444)
relative velocity the velocity of an object relative to a
specific frame of reference (p. 44)
relativistic kinetic energy (Ek) the energy of an object in
excess of its rest energy (p. 599)
relativistic length (Lm) the length of an object or the
distance between two points as measured by an
observer moving with respect to the object or
distance (p. 589)
relativistic mass the mass of an object measured by an
observer moving with speed v with respect to the
object (p. 595)
relativistic momentum the momentum of objects moving
at speeds near the speed of light (p. 594)
relativistic time time that is not absolute, but changes
relative to the observer (p. 583)
resolution the ability of an optical device to separate close
objects into distinct and sharp images (p. 517)
rest energy (Erest) the amount of energy an object at rest
has with respect to an observer (p. 599)
rest mass the mass of an object measured at rest with
respect to the observer; also called the proper
mass (p. 595)
730 Glossary
8160_Glossary_p725-731.indd 730
if you point your right thumb
in the direction of the
>
fingers in
velocity of the charge (v ), and your straight
>
the direction of the magnetic field (B ), then your palm
will point
> in the direction of the resulting magnetic
force (F M) (p. 387)
right-hand rule for a solenoid if you coil the fingers of
your right hand around a solenoid in the direction of
the conventional current, your thumb points in the
direction of the magnetic field lines in the centre of
the coil (p. 383)
right-hand rule for a straight conductor if your right
thumb is pointing in the direction of conventional
current, and you curl your fingers forward, your
curled fingers point in the direction of the magnetic
field lines (p. 382)
S
satellite an object or a body that revolves around another
body due to gravitational attraction (p. 297)
scalar a quantity that has magnitude (size) but no
direction (p. 8)
scattering the change in direction of light waves as a result
of collisions (p. 535)
secant a straight line connecting two separate points
on a curve (p. 9)
secondary maxima the progressively less-intense bright
areas, outside the central region, in an interference
pattern (p. 512)
simple harmonic motion periodic motion in which the
acceleration of the moving object is proportional to
its displacement (p. 197)
simultaneity the occurrence of two or more events at the
same time (p. 591)
Snell’s law n 1 sin u 1 5 n 2 sin u 2 (p. 447)
space station a spacecraft in which people live and work
(p. 298)
space-time a four-dimensional coordinate system in
which the three space coordinates are combined with
time, a fourth dimension (p. 594)
special theory of relativity all physical laws are the same
in all inertial frames of reference, and the speed of
light is independent of the motion of the light source
or its observer in all inertial frames of reference
(p. 578)
specular reflection the reflection of light from a surface
where all the reflected rays are in the same direction
(p. 442)
spring constant (k) the constant of variation between
the force exerted by an ideal spring and the spring’s
displacement (p. 192)
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standard model the modern theory of fundamental
particles and> their interactions (p. 648)
static friction (F S) a force that resists attempted motion
between two surfaces in contact (p. 63)
superposition principle the resultant, or net, vector acting
at a given point equals the sum of the individual
vectors from all sources, each calculated at the
given point (p. 329)
T
tangent a straight line that intersects a curve at a point
and has the same slope as the curve at the point of
intersection (p. 12)
>
tension (F T) a force exerted by objects that can be
stretched (p. 62)
tesla the SI unit of measure for describing the strength of a
kg
magnetic field; 1 T 5 1 # (p. 386)
Cs
theory of everything a theory that attempts to combine three
fundamental forces (weak, strong, and electromagnetic)
with gravity into a single theory (p. 652)
thin film a very thin layer of a substance, usually on a
supporting material (p. 502)
thought experiment a mental exercise used to investigate
the potential consequences of a hypothesis or
postulate (p. 577)
threshold frequency ( f0 ) the minimum frequency at which
electrons are ejected from a metal (p. 621)
time dilation the slowing down of time in one reference
frame moving relative to an observer in another
reference frame (p. 580)
total internal reflection an effect that occurs when light
encounters a boundary between a medium with a
higher index of refraction and one with a lower index
of refraction (p. 453)
transmission axis the direction of the electric field that a
polarizer allows through (p. 533)
trough the lower part of a wave (p. 441)
twin paradox a thought experiment in which a traveller in
one frame of reference returns from a voyage to learn
that time had passed more slowly in his spacecraft
relative to the passage of time on Earth, despite the
seemingly symmetric predictions of special relativity
(p. 593)
NEL
8160_Glossary_p725-731.indd 731
U
uniform circular motion the motion of an object with a
constant speed along a circular path of constant radius
(p. 114)
universal law of gravitation there is a gravitational attraction
between any two objects; if the objects have masses m1
and m2 and their centres are separated by a distance r,
the magnitude of the gravitational force on either object
is directly proportional to the product of m1 and m2 and
inversely proportional to the square of r (p. 288)
unpolarized light light waves that vibrate in many different
planes (p. 532)
V
vector a quantity that has both magnitude (size) and
direction (p. 8)
>
velocity (v ) the change in position divided by the time
interval (p. 9)
W
wave front the continuous line or surface at the start of a
wave as it travels in time (p. 441)
wavelength (λ) the distance between one positive
amplitude and the next (p. 441)
wave–particle duality the property of matter that defines
its dual nature of displaying both wave-like and
particle-like characteristics (p. 618)
weight the gravitational force exerted by Earth on an
object (p. 75)
work the product of the magnitude of an object's
displacement and the component of the applied force
in the direction of the displacement (p. 164)
work–energy theorem the total work done on an object
equals the change in its kinetic energy (p. 173)
work function (W) the minimum energy needed to remove
an electron bound to a metal surface (p. 620)
Z
zero-order maximum the location of maximum intensity
in the diffraction pattern at u 5 08 (p. 521)
Glossary
731
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