"Physics is Fun"
(Feimer's Physics Page)
Physics Dictionary
Absolute zero: lowest possible temperature at which gas would
have a zero volume.
Absorption spectrum: spectrum of electromagnetic radiation absorbed
by matter when radiation of all frequencies is passed through it.
Acceleration: change in velocity divided by time interval over
which it occurred.
Accuracy: closeness of a measurement to the standard value of
that quantity.
Achromatic lens: lens for which all light colors have the same
focal length.
Action-reaction forces: pair of forces involved in an interaction
that are equal in magnitude and opposition in direction.
Activity: number of decays per second of a radioactive substance.
Adhesion: force of attraction between two unlike materials.
Air resistance: force of air on objects moving through it.
Alpha decay: process in which a nucleus emits an alpha particle.
Alpha particle: positively- charged particles consisting of two
protons and two neutrons emitted by radioactive materials.
Ammeter: device to measure electrical current.
Amorphous solid: solids that have no long- range order; no crystal
structure.
Ampere: unit of electric current; one ampere is the flow of one
coulomb of charge per second.
Amplitude: in any periodic motion, the maximum displacement from
equilibrium.
Angle of incidence: angle between direction of motion of waves
and a line perpendicular to surface the waves are striking.
Angle of reflection: angle between direction of motion of waves
and a line perpendicular to surface the waves are reflected from.
Angle of refraction: angle between direction of motion of waves
and a line perpendicular to surface the waves have been refracted from.
Angular momentum: quantity of rotational motion. For a rotating
object, product of moment of inertia and angular velocity.
Annihilation: process in which a particle and its antiparticle
are converted into energy.
Antenna: device used to receive or transmit electromagnetic waves.
Antineutrino: subatomic particle with no charge or mass emitted in
beta decay.
Antinode: point of maximum displacement of two superimposed waves.
Archimedes’ principle: object immersed in a fluid has an upward
force equal to the weight of the fluid displaced by the object.
Artificial radioactivity: radioactive isotope not found in nature.
atomic mass unit: unit of mass equal to 1/12 the atomic mass
of carbon- 12 nucleus.
Atomic number: number of protons in the nucleus of the atom.
Average acceleration: acceleration measured over a finite time
interval
Average velocity: velocity measured over a finite time interval.
Back-EMF: potential difference a cross a conductor caused by change
in magnetic flux.
Band theory: theory explaining electrical conduction in solids.
Baryon: subatomic particle composed of three quarks. Interacts
with the strong nuclear force.
Battery: device that converts chemical to electrical energy consisting
of two dissimilar conductors and an electrolyte.
Beat : slow oscillation in amplitude of a complex wave
Bernoulli’s principle: when a fixed quantity of fluid flows,
the pressure is decreased when the flow velocity increases.
Beta decay: radioactive decay process in which an electron or
positron and neutrino is emitted from a nucleus.
Beta particle: high speed electron emitted by a radioactive nucleus
in beta decay.
Binding energy: negative of the amount of energy needed to separate
a nucleus into individual nucleons.
Boiling point: temperature at which a substance, under normal
atmospheric pressure, changes from a liquid to a vapor state.
Breeder reactor: nuclear reactor that converts nonfissionable
nuclei to fissionable nuclei while producing energy.
Bubble chamber: instrument containing superheated liquid in which
the path of ionizing particles is made visible as trails of tiny bubbles.
Buoyant force: upward force on an object immersed in fluid.
Calorimeter: device that isolates objects to measure temperature
changes do to heat flow.
Candela: unit of luminous intensity.
Capacitance: ratio of charge stored per increase in potential
difference.
Capacitor: electrical device used to store charge and energy
in the electrical field.
Capillary action: rise of liquid in narrow tube due to surface
tension.
Carnot efficiency: ideal efficiency of heat engine or refrigerator
working between two constant temperatures.
Centripetal force: force that causes centripetal acceleration.
Chain reaction: nuclear reaction in which neutrons are produced
that can cause further reactions.
Charged : object that has an unbalance of positive and negative
electrical charges.
Charging by conduction: process of charging by touching neutral
object to a charged object.
Charging by induction: process of charging by bringing neutral
object near charged object, then removing part of resulting separated charge.
Chromatic aberration: variation in focal length of lens with
wavelength of light.
Circular motion: motion with constant radius of curvature caused
by acceleration being perpendicular to velocity.
Clock reading: time between event and a reference time, usually
zero.
Closed, isolated system: collection of objects such that neither
matter nor energy can enter or leave the collection.
Closed-pipe resonator: cylindrical tube with one end closed and
a sound source at other end.
Coefficient of friction: ratio of frictional force and the normal
force between two forces.
Coefficient of linear expansion: change in length divided by
original length and by temperature change.
Coefficient of volume expansion: change in volume divided by
original volume and by temperature change.
Coherent waves: waves in which all are in step; are in phase.
Cohesive force: attractive force between similar substances.
Complementary color: two colors that, when added , produce white
light. Two pigments, that when combined, produce black.
Compound machine: machine consisting of two or more simple machines.
Compton effect: interaction of photons, usually X rays, with
electrons in matter resulting in increased wavelength of X rays and kinetic
energy of electrons.
Concave lens: lens thinner in center than edges; a diverging
lens.
Concave mirror: converging mirror, one with center of curvature
on reflecting side of mirror.
Conduction band: energies of charge carries in a solid such that
the carries are free to move.
Conductor: materials through which charged particles move readily;
or heat flow readily.
Conserved properties: property that is the same before
and after an interaction.
Consonance: two or more sounds that, when heard together, sound pleasant.
Constant acceleration: acceleration that does not change in time.
Constant velocity: velocity that does not change in time.
Constructive interference: superposition of waves resulting in
a combined wave with amplitude larger than the component waves.
Convection: heat transfer by means of motion of fluid.
Conventional current: motion of positive electrical current.
Converging lens: lens that causes light rays to converge; usually
a convex lens.
Convex lens: lens that is thicker in the center than at edges.
Convex mirror: diverging mirror. Center of curvature is
on side opposite reflecting side of mirror.
Cosine: the ratio of the adjacent side to the hypotenuse.
Coulomb: unit of electrical charge. Charge caused by flow
of one ampere for one second.
Crest of wave: high point of wave motion.
Critical angle: minimum angle of incidence that produces total
internal reflection.
Crystal lattice: structure of solid consisting of regular arrangment
of atoms.
De Broglie wavelength: length of de Broglie wave of particle;
Planck’s constant divided by momentum of particle.
Decibel: unit of sound level.
Dependent variable: variable that responds to change in manipulated
variable.
Derived units: unit of quantity that consists of combination of fundamental
units.
Destructive interference: superposition of waves resulting in
a combined wave with zero amplitude.
Diffraction: bending of waves around object in their path.
Diffraction grating: material containing many parallel lines
very closely spaced that produces a light spectrum by interference.
Diffuse reflection: reflection of light into many directions by rough
object.
Dimensional analysis: checking a derived equation by making sure
dimensions are the same on both sides.
Diode: electrical device permitting only one way current flow.
Dispersion of light: variation with wavelength of speed of light
through matter resulting in separation of light into spectrum.
Displacement: change in position. A vector quantity.
Dissonance: two or more sounds that, when together, sound unpleasant.
Distance: separation between two points. A scalar quantity.
Diverging lens: lens that causes light rays to spread apart or
diverge; usually a concave lens.
Dopants: small quantities of material added to semiconductor
to increase electrical conduction.
Doppler shift: change in wavelength due to relative motion of
source and detector.
Dynamics: study of motion of particles acted on by forces.
Effective current: DC current that would produce the same heating
effects.
Effective voltage: DC potential difference that would produce
the same heating effects.
Efficiency: ratio of output work to input work.
Effort force: force extended on a machine.
Elastic collision: interaction between two objects in which the
total energy is the same before and after the interaction.
Elasticity: ability of object to original shape after deforming
forces are removed.
Electrical charge pump: device, often a battery or generator,
that increase potential of electrical charge.
Electrical circuit: continuous path through which electrical
charges can flow.
Electrical current: flow of charged particles.
Electrical field: property of space around a charged object that
causes forces on other charged objects.
Electric field lines: lines representing the direction of electric
field.
Electric field strength: ratio of force exerted by field on a
tiny test charge to that change.
Electric generator: device converting mechanical energy into
electrical energy.
Electric potential: ratio of electric potential energy to charge.
Electric potential difference: difference in electric potential
between two points.
Electric potential energy: energy of a charged body in an electrical
field.
Electromagnet: device that uses an electric current to produce
a concentrated magnetic field.
Electromagnetic force: one of fundamental forces due to electric
charges, both static and moving.
Electromagnetic induction: production of electric field or current
due to change in magnetic flux.
Electromagnetic radiation: energy carried by electromagnetic
waves throughout space.
Electromagnetic waves: wave consisting of oscillating electric
and magnetic fields that move at speed of light through space.
Electromotive force: potential difference produced by electromagnetic
induction.
Electron: subatomic particle of small mass and negative charge
found in every atom.
Electron cloud: region of high probability of finding an electron
around an atom.
Electron diffraction: effects on electrons due to wave-like interference
of electrons with matter.
Electron gas model: description of current flow through conductors.
Electroscope: device to detect electric charges.
Electrostatics: study of properties and results of electric charges
at rest.
Electroweak force: unification of electromagnetic and weak forces.
Elementary charge: magnitude of the charge of an electron. 1.602
*10^ -19
Emission spectrum: spectrum produced by radiation from excited
atoms.
Energy: non-material property capable of causing changes in matter.
Energy levels: amounts of energy an electron in an atom may have.
Entropy: measure of disorder in a system; ratio of heat added
to temperature.
Equilibrant force: force needed to bring an object into transitional
equilibrium.
Equilibrium: condition in which net force is equal to zero.
Condition in which net torque on object is zero.
Equivalent resistance: single resistance that could replace several
resistors.
Evaporation: change from liquid to vapor state.
Excited state: energy level of atom higher than ground state.
External forces: forces exerted from outside a system.
Extrinsic semiconductor: semiconductor in which conduction is
primarily the result of added impurities.
Factor-label method: dimensional analysis.
Farad: unit of capacitance. One coulomb per volt.
Ferromagnetic materials: materials in which large internal magnetic
fields are generated by cooperative action of electrons.
First harmonic: in music, the fundamental frequency.
First law of thermodynamics: change in internal or thermal energy
is equal to heat added and work done on system. Same as law of conservation
of energy.
Fluid: material that flows, i.e. liquids, gases, and plasmas.
Focal length: distance from the focal point to the center of
a lens or vertex of a mirror.
Focal point: location at which rays parallel to the optical axis
of an ideal mirror or lens converge to a point.
Forbidden gap: energy values that electrons in a semiconductor
or insulator may not have.
Force: agent that results in accelerating or deforming an object.
Frame of reference: coordinate system used to define motion.
Fraunhofer lines: absorption lines in the sun’s spectrum due
to gases in the solar atmosphere.
Frequency: number of occurrences per unit time.
Friction: force opposing relative motion of two objects are in
contact.
Fundamental particles: those particles( i.e. quarks and leptons)
of which all materials are composed.
Fundamental tone: lowest frequency sound produced by a musical
instrument.
Fundamental units: set of units on which a measurement system
is based( i.e. meter, second, kilogram, ampere, candela).
Fuse: metal safety device in an electric circuit that melts to
stop current flow when current is too large.
Fusion: combination of two nuclei into one with release of energy.
Galvanometer: device used to measure very small currents.
Gamma decay: process by which a nucleus emits a gamma ray.
Gamma particle: high energy photon emitted by a radioactive nucleus.
Gas: state of matter that expands to fill container.
Geiger-Mueller tube: device used to detect radiation using its
ability to ionize matter.
General theory of relativity: explanation of gravity and accelerated
motion invented by Einstein.
Gluon: carrier of strong nuclear force.
Grand unified theories: theories being developed that unify the
stronger and electroweak forces into one force.
Gravitational field: distortion of space due to the presence
of mass.
Gravitational force: attraction between two objects due to their
mass.
Gravitational mass: ratio of gravitational force to object’s
acceleration.
Gravitational potential energy: change of energy of object when
moved in a gravitational field.
Graviton: particle that carries the gravitational force.
Not yet observed.
Ground state: lowest energy level of an electron in an atom.
Grounding: process of connecting a charged object to Earth to
remove object’s unbalanced charge.
Half-life: length of time for half of a sample of radioactive
material to decay.
Harmonics: frequencies produced by musical instrument that are
multiples of fundamental tone.
Heat: quantity of energy transferred from one object to another
because of a difference in temperature.
Heat engine: device that converts thermal energy to mechanical
energy.
Heat of fusion: quantity of energy needed to change a unit mass
of a substance from solid to liquid state at the melting point.
Heat of vaporization: quantity of energy needed to change a unit
mass of a substance from liquid to gaseous state at the boiling point.
Heavy water: deuterium oxide used mainly in CANDU nuclear reactors.
Heisenberg uncertainty principle: the more accurately one determines
the position of a particle, the less accurately the momentum can be known,
and vice versa.
Hertz: unit of frequency equal to one event or cycle per second.
Hole: absence of an electron in a semiconductor.
Hooke’s law: deformation of an object is proportional to force
causing it.
Huygens’ wavelets: model of spreading of waves in which each
point on wavefront is source of circular or spherical waves.
Hydraulic system: machines using fluids to transmit energy.
Hyperbola: mathematical curve that describes an inverse relationship
between two variables.
Hypotenuse: side opposite the right angle in a triangle.
Ideal mechanical advantage: in simple machine, the ratio of effort
distance to resistance distance.
Illuminance: rate at which electromagnetic wave energy falls
on a surface.
Illuminated object: object on which light falls.
Image: reproduction of object formed with lenses or mirrors.
Impulse: product of force and time interval over which it acts.
Impulse-momentum theorem: impulse given to an object is equal
to its change in momentum.
Incandescent body: object that emits light because of its high
temperature.
Incident wave: wave that strikes a boundary where it is either
reflected or refracted.
Incoherent light: light consisting of waves that are not in step.
Independent variable: variable that is manipulated or changed
in an experiment.
Index of refraction: ratio of the speed of light in vacuum to
its speed in a material.
Inelastic collision: collision in which some of the kinetic energy
is changed into another form.
Inertia: tendency of object not to change its motion.
Inertial mass: ratio of net force exerted on object to its acceleration.
Initial velocity: velocity of object at time t=0.
Instantaneous acceleration: acceleration at a specific time;
slope of tangent to velocity- time graph.
Instantaneous position: position of an object at specific time.
Instantaneous velocity: slope of the tangent to position- time
graph.
Insulator: material through which the flow of electrical charge
carriers or heat is greatly reduced.
Interference fringes: pattern of dark and light bands from interference
of light waves.
Interference of waves: displacements of two or more waves, producing
either large or smaller waves.
Internal forces: forces between objects within a system.
Intrinsic semiconductor: semiconductor in which conduction is
by charges due to host material, not impurities.
Inverse relationship: mathematical relationship between two variables,
x and y, summarized by the equation xy=k, where k is a constant.
Ionizing radiation: particles or waves that can remove electrons
from atoms, molecules, or atoms in a solid.
Isolated system: a collection of objects not acted upon by external
forces into which energy neither enters nor leaves.
Isotope: atomic nuclei having same number of protons but different
numbers of neutrons.
Joule: SI unit of energy equal to one Newton-meter.
Joule heating: increase in temperature of electrical conductor
due to conversion of electrical to thermal energy.
Kelvin temperature scale: scale with 0 K= absolute zero and 273.16
K = triple point of water.
Kepler’s laws: three laws of motion of bodies attracted together
by the gravitational force.
Kilogram: SI unit of mass.
Kilowatt hour: amount of energy equal to 3.6 * 10^ 6 J.
Usually used in electrical measurement.
Kinematics: study of motion of objects without regard to the
causes of this motion.
Kinetic energy: energy of object due to its motion.
Kinetic-molecular energy: description of matter as being made
up of extremely small particles in constant motion.
Laser: devise that produces coherent light by stimulated emission of
radiation.
Laser- induced fusion: proposed method of creating nuclear fusion
by using heating caused by intense laser beams to squeeze matter together.
Law of conservation of energy: in a closed, isolated system,
the total momentum is constant.
Law of reflection: angle of incidence of a wave is equal to the
angle of reflection.
Law of universal gravitation: gravitational force between two
objects depends directly on the product of their masses and inversely on
the square of their separation.
Lens: optical device designed to converge or diverge light.
Lens equation: See mirror equation.
Lenz’s law: magnetic field generated by an induced current opposes
the change in field that caused the current.
Lepton: particle that interacts with other particles only by
the electroweak and gravitational interactions.
Lever arm: component of the displacement of the force from the
axis of rotation in the axis of rotation in the direction perpendicular
to the force.
Light: electromagnetic radiation with wavelengths between 400
and 700 nm that is visible.
Linear accelerator: device to accelerate subatomic particles
by applying successive electric field.
Linear relationship: relationship between two variables, x and
y, summarized by the equation y= ax + b, where a and b are constant.
Linear restoring force: force in direction toward equilibrium
position that depends linearly on distance from distance from that position.
Liquid: materials that have fixed volume but whose shape depends
on the container.
Lodestone: naturally occurring magnetic rock.
Longitudinal waves: wave in which direction of disturbance is
the same as the direction of travel of wave.
Loudness: physiological measure of amplitude of a sound wave;
heard on pitch and tone color as well as amplitude.
Lumen: unit of luminous flux.
Luminance intensity: measure of light emitted by source in candelas;
luminous flux divided by 4pie.
Luminous flux: flow of light from source measured in lumens.
Luminous object: object that emits light, as opposed to one that
reflects light.
Lux: unit of luminous flux; one lumen per square meter.
----------------
The Letter M:
Machine: device that changes force needed to do work.
Magnetic field: space around a magnet throughout which magnetic
force exists.
Magnification: ratio of size of an optical image to the size
of the object.
Manipulated variable: variable that the experimenter can change.
Mass defect: mass equivalent of the binding energy; m=E/c^ 2
Mass number: number of nucleons ( protons plus neutrons) in the
nucleus of an atom.
Mass spectrometer: device used to measure the mass of atoms or
molecules.
Matter wave: wave-like properties of particles such as electrons.
Mechanical advantage: ratio of resistance force to effort force
in a machine.
Mechanical energy: sum of potential and kinetic energy.
Mechanical resonance: condition at which natural oscillation
frequency equals frequency of driving force; amplitude of oscillatory motion
at a maximum.
Mechanical wave: wave consisting of periodic motion of matter;
e.g. sound wave or water wave as opposed to electromagnetic wave.
Melting point: temperature at which substance changes from solid
to liquid state.
Meson: medium mass subatomic particle consisting of combination
of a quark and antiquark.
Meter: SI unit of length.
Mirror equation: 1/do +1/di=1/f, where do is object distance,
di is image distance, f is focal length.
Moderator: material used to decrease speed of neutrons in nuclear
reactor.
Momentum: product of object’s mass and velocity.
Monochromatic light: light of a single wavelength.
Mutual inductance: measures the amount of overlap between the
magnetic flux produced in one coil and that which passes through a second
coil, thus the amount of EMP induced in a secondary coil by the varying
flux in the primary coil.
Myopia: defect of eye, commonly called nearsightedness, in which
distant objects focus in front of the retina.
n-type semiconductor: semiconductor in which current is carried
by electrons.
Net force: vector sum of forces on object.
Neutral: object that has no net electric charge.
Neutrino: chargeless, massless, subatomic particle emitted with
beta particles; type of lepton.
Neutron: subatomic particle with no charge and mass slightly
greater than that of proton; type of nucleon.
Newton: SI unit of force.
Newton’s law of motion: laws relating force and acceleration.
Node: point where disturbances caused by two or more waves result
in no displacement.
Normal: perpendicular to plane of interest.
Normal force: force perpendicular to surface.
Nuclear equation: equation representing a nuclear reaction.
Nuclear fission: reaction in which large nucleus splits into
two parts, often approximately equal in mass.
Nuclear fusion: reaction in which two nuclei are combined into
one.
Nuclear reaction: reaction involving the strong force in which
the number of protons or neutrons in a nucleus changes.
Nuclear reactor: device in which nuclear fusion is used to generate
electricity.
Nuclear transmutation: change of one nucleus into another as
the result of a nuclear reaction.
Nucleon: either a proton or a neutron.
Nuclide: nucleus of an isotope.
Object: source of diverging light rays; either luminous or illuminated.
Octave: interval between two frequencies with a ratio of two
to one.
Ohm: SI unit of resistance; one volt per ampere.
Ohm’s law: resistance of object is constant, independent of voltage
across it.
Opaque: material that does not transmit light.
Open- pipe resonator: cylindrical tube with both ends closed
and a sound source at one end.
p-type semiconductor: semiconductor in which conduction is the
result of motion of holes.
Pair production: formation of particle and antiparticle from
gamma rays.
Parabolic mirror: mirror the shape of a paraboloid of revolution
that has no spherical aberration.
Parallel circuit: circuit in which there are two or more paths
for current flow.
Parallel connection: connection of two or more electrical devices
between two points to provide more than one current path.
Pascal: SI unit of pressure; one neutron per square meter.
Pascal’s principle: pressure applied to a fluid is transmitted
undiminished throughout it.
Period: time needed to repeat one complete cycle of motion.
Periodic motion: motion that repeats itself at regular intervals
of time.
Photoelectric effect: election of electrons from surface of metal
exposed to electromagnetic radiation.
Photon: quantum of electromagnetic waves; particle aspect of
these waves.
Photovoltaic cell: device that converts electromagnetic radiation
into electrical energy.
Physics: study of matter and energy and their relationship.
Piezoelectricity: electric potential produced by deforming material.
Pigment: colored material that absorbs certain colors and transmits
or reflects others.
Pitch: perceived sound characteristics equivalent to frequency.
Planck’s constant: ratio of energy of photon to its frequency.
Plane mirror: flat, smooth surface that reflects light regularly.
Plasma: state of matter in which atoms are separated into electrons
and positive ions or bare nuclei.
Point object: object idealized as so small to be located at only
one position.
Polarized light: light in which electric fields are all in same
plane.
Position: separation between object and a reference point.
Position- time graph: graph of object’s motion that shows how
its position depends on clock reading, or time.
Positron: antiparticle equivalent of electron.
Potential difference: difference in electric potential between
two points.
Potential energy: energy of object due to its position or state.
Potentiometer: electrical device with variable resistance; rheostat.
Power: rate of doing work; rate of energy conversion.
Precision: degree of exactness in a measurement.
Pressure: force per unit area.
Primary coil: transformer coil that, when connected to voltage
source, creates varying magnetic flux.
Primary light colors: red, green, or blue light.
Primary pigment: yellow, green, or magenta light.
Principal axis: line connecting center of curvature of spherical
mirror with its geometric vertex. Line perpendicular to plane of
lens passing through its center.
Principle of superposition: displacement due to two or more forces
is equal to vector sum of forces.
Projectiles: motion of objects given initial velocity that then
move only under force of gravity.
Proton: subatomic particle with positive charge that is nucleus
of hydrogen atom.
quantized: a quantity that cannot be divided into smaller increments
forever, for which there exists a minimum, quantum increment.
Quantum mechanic: study of properties of matter using its wave
properties.
Quantum model of atom: atomic model in which only probability
of locating electron is known.
Quantum number: integer ratio of energy to its quantum increment.
Quark: basic building block of protons, neutrons, other baryons,
and mesons.
Quark model: model in which all particles that interact via the
strong interaction are composed of two or three quarks.
Radiation: electromagnetic waves that carry energy.
Radioactive decay: spontaneous change of unstable nuclei into
other nuclei.
Radioactive materials: materials that undergo radioactive decay.
Range of projectile: horizontal distance between launch point
of projectile and where it returns to launch height.
Ray model of light: light may be represented by straight line
along direction of motion.
Ray optics: study of light using ray model.
Rayleigh criterion: two optical images are separable if central
bright spot of one image falls on first dark band of second.
Real image: optical image at which rays from object converge.
Receiver: device that detects electromagnetic waves.
Reference level: location at which potential energy is chosen
to be zero.
Reference point: zero location in a coordinate system or frame
of reference.
Refraction: change in direction of light ray when passing one
medium to another.
Refractive index: ratio of speed of light in vacuum to that in
the medium.
Resistance: ratio of potential difference across device to current
through it.
Resistance force: force exerted by a machine.
Resistor: device designed to have a specific resistance.
Responding variable: variable that changes as result of change
in manipulated variable.
Rest energy: energy due to mass of object; E= mc^ 2.
Resultant: vector sum of two or more vectors.
Right -hand rules: used to find force on current or moving particle
in magnetic field; used to find direction of magnetic field caused by current
or of induced EMF.
Rutherford’s model of atom: nuclear model of atom; essentially
all mass in compact, positively- charged object at center, surrounded by
electrons.
Scalar: quantity, like distance, that has only a magnitude, or
size.
Schematic diagram: representation of electric circuit using symbols.
Scientific notation: numbers expressed in form M * 10 ^
n , where 1< M < 10, and n is an integer.
Scintillation: flash of light emitted when substance is struck
by radiation.
Second: SI unit of time.
Second law of thermodynamics: heat flow only from region of high
temperature o region of lower temperature.
Secondary coil: transformer coil in which varying EMF is induced.
Secondary light colors: yellow, cyan, or magenta light.
Secondary pigment: red, green, or blue pigment.
Self- inductance: induced EMF produced in coil by changing current.
Semiconductor: material in which electrical conduction is smaller
than that in a conductor, but more than in insulator.
Series circuit: circuit in which electrical current flows through
each component, one after another.
Series connection: arrangement of electrical devices so that
there is only one path through which current can flow.
Short circuit: low resistance connection between two points,
often accidental.
SI: internationally agreed -upon method of using the metric system
of measurement.
Significant digit: reliable digits reported in a measurement.
Simple harmonic motion: motion caused by linear restoring that
has a period independent of amplitude of motion.
Simple machine: machine consisting of only one lever, inclined
plane, wedge, screw, pulley, or wheel and axle.
Sine: the ratio of the opposite side and the hypotenuse.
Sliding friction: force between two surfaces in relative motion.
Slope: ratio of the vertical separation, or rise to the horizontal
separation, or run.
Solid: state of matter with fixed volume and shape.
Sound level: quantity measuring logarithm of sound intensity
in decibels.
Spark chamber: device used to detect path of charged subatomic
particles by a spark that jumps along path of ionization created in a gas.
Specific heat: thermal energy needs to change temperature of
unit mass of substance one Kelvin.
Spectroscope: device used to study spectrum of material.
Spectrum: collection of wavelengths in electromagnetic spectrum.
Speed: ratio of distance traveled to time interval.
Speed of light: in vacuum, 2.9979458 * 10^8 m/s.
Spherical aberration: inability of spherical mirror to focus
all parallel rays to a single point.
Standing wave: wave with stationary nodes.
Static friction: force that opposes start of motion between two
surfaces.
Step- down transformer: transformer with output voltage smaller
than input voltage.
Step- up transformer: transformer with output voltage larger
than input voltage.
Stimulated emission: emission of photon from excited atom caused
by impact fo photon of same energy.
Strong nuclear force: force of very short range that holds neutrons
and protons in nucleus together.
Superconductor: electrical conductor that has no resistance and
low temperatures.
Surface wave: wave on surface of liquid with characteristics
of both longitudinal and transverse waves.
Symmetry: property that is now charged when operation or reference
frame is charged.
Synchrotron: device to accelerate particles in which particles
move in circular path.
System: defined collection of objects.
tangent: the ratio of the opposite side and the adjacent side.
Temperature: measure of hotness of object on a quantitative scale.
In gases, proportional to average kinetic energy of molecules.
Terminal velocity: velocity of falling object reached when force
of air resistance equals weight.
Test charge: charge used, in principle, to measure electric field.
Thermal energy: internal energy. Sum of kinetic and potential
energy of random motion of particles making up object.
Thermal equilibrium: state between two or more bodies where temperatures
do not change.
Thermal expansion: increase of length or volume of object due
to change in temperature.
Thermometer: device used to measure temperature.
Thermonuclear reaction: nuclear fusion.
Thin- film interference: light interference caused by reflection
from both front and rear surface of thin layer of liquid or solid.
Timbre: sound quality or tone color; spectrum of sound frequencies
that produce a complete wave.
Time interval: difference in time between two clock readings.
Tokamak: type of fusion reactor.
Tone color: timbre or tone quality.
Torque: product of force and the lever arm.
Trajectory: the path followed by projectile.
Transformer: device to transform energy from one electrical circuit
to another by means of mutual inductance between two coils.
Transistor: semiconductor device that controls large current
by means of small voltage changes.
Translucent: material transmitting light without but distorting
its path.
Transmutation: nuclear change from one element to another.
Transparent: material transmitting light without distorting directions
of waves.
Transverse waves: wave in which disturbance is perpendicular
to direction of travel of wave.
Traveling wave: moving, periodic disturbance in a medium or field.
Trigonometry: branch of math that deals with the relationship
among angles and sides of triangles.
Trough of wave: low point of wave motion, where displacement
is most negative.
Uniform acceleration: constant acceleration.
Uniform circular motion: motion in a circle of constant radius
with constant speed.
Valence band: in a solid, the range of energies of electrons that
are bound to atoms.
Vector quantity: quantity having both magnitude (size) and direction.
Vector resolution: process of finding the effective value of
a component in a given direction.
Velocity: ratio of change in position to time interval over which
change takes place.
Velocity- time graph: plot of velocity of object as a function
of time.
Virtual image: point from which light rays appear to diverge
without actually doing so.
Viscous fluid: fluid that creates force that opposes motion of
objects through it. The force is proportional to object’s speed.
Volatile liquid: liquid that is easily vaporized.
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The Letter W:
Watt: unit of power, one joule per second.
Wavelength: distance between corresponding points on two successive
waves.
Wave pulse: single disturbance moving through a medium or field.
Weak boson: particle that carries or transmits the weak interaction
of force.
Weak interaction: force involved in beta decay of the neutron
and atomic nuclei; one aspect of the electroweak force.
Weight: force of gravity of an object.
Weightlessness: object in freefall, on which only the gravitational
force acts.
Wilson cloud chamber: chamber containing supersaturated vapor
through which ionizing radiation leaves trails of visible droplets.
Work: product of force and displacement in the direction of the
force.
Work function: energy needed to remove an electron from metal.
Work energy theorem: work done on object is equal to the change
in its kinetic energy.
X ray: high- energy photons; high- frequency, short-wavelength
electromagnetic waves.
X-ray diffraction: A complicated technique using x-rays to "create
an image" where no lense to focus the light rays is available.
X-ray images: Images such as photographs or computer enhanced
images produced by bombarding a target with x-rays.
Young's modulus: A constant of proportionality associated with the change in length of a material according to its elastic properties.
Zero-point energy: The lowest energy state of molecular vibration