Flashcard glossary

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absolute uncertainties Plus or minus  the uncertainty
absolute zero The lowest temperature possible zero K
accelerationThe rate of change of velocity
accurate measurementclose to the accepted value
activityThe rate of decay
adiabatic transformations No exchange of heat
air resistance The force of air opposing motion
air wedge interferenceThe interference of light reflected off to angled glass plates
albedo The ratio of scattered light to incident light
Algodooapplication used to simulate motion
alpha particles Helium nuclei emitted by unstable nuclei.
alpha scattering experiment High-speed positive particles fired at a thin gold foil.
alternating current (AC) Electric current that changes direction and magnitude.
alternators A rotating magnet in a coil.
ammeters Device for measuring current.
amp (unit) The Unit of current same as Coulomb per Second
Ampere1A causes a force of 2 x 10^-7 N between to long conductors 1 m apart in a vacuum
amplitudeHeight of a wave measured from equilibrium position
amplitude The maximum displacement of a pendulum.
ancient Greeks Philosophers a long time ago
angle of incidence The angle between the normal and the incident ray.
angle of reflection The angle between the normal and the reflected ray.
angle of refraction The angle between the Normal and the refracted ray.
angular displacementThe angle swept out by the radius.
angular frequencyThe angle swept out per unit time.
Angular momentummvr
angular velocity     The angle swept out per unit time
annihilationparticle + antiparticle = energy but no mass
antimatterMatter made up of anti particles
antineutrinosAntiparticle of neutrino
antinodesPositions on a standing wave with zero amplitude.
antireflective coating An application of thin film interference
apparent brightness (stars) Brightness from the Earth
apparent magnitude (stars) Brightness from 10 pc
area under a-t graphchange in velocity
area under force - time graphWork
area under force distance graphWork
area under grapharea under the line
area under v-t graphdisplacement
asteroids Rocks orbiting the sun
astronomical units Sun - Earth distance
atmospheric pressure The pressure exerted by air.
atom bombs Application of an accelerating chain reaction.
atomic latticeA regular arrangement of atoms
atomic line spectra The spectrum formed when a low pressure gas is excited. Evidence of discrete electron energy levels.
atomic nuclei Heavy, small, positive centre of an atom
atoms Smallest particle of an element.
attenuationReduction in amplitude
Aurora BorealisGlow in the night sky in the north due to the interaction betweencharged particles and the atmosphere
average value of sine function00-Jan
average velocityDisplacement / time
average velocitydisplacement/time
Avogadro's number The number of particles in a mole.
background radiation  Radiation in a room due to naturally occurring radioactive material
balanced forces Condition for no acceleration.
baryons A group of particles including proton and neutron.
batteries Cells in series.
BE (see binding energy)The work done to take a nucleus apart or energy released when it is formed.
becquerel (unit) Unit of activity.
best fit lineA line drawn as close as possible to the data points
beta particlesAn electron formed when a neutron changes to a proton.
Big BangA model for the start of the universe.
big crunch A model for the end of the universe.
binary starsPairs of stars that orbit each other.
binding energy (BE)The work done to take a nucleus apart or energy released when it is formed.
black holes The fate of massive stars.
blue shift Doppler shift in approaching sources of light.
Bohr model Atomic model assuming angular momentum to be quantised
boiling Change of state from liquid to gas.
boron control rodsAbsorb neutrons slowing down the chain reaction
Brownian motionThe randon motion of smoke particles knocked about by air molecules.
buoyancyUpward force due to displacement of fluid.
capacitancecharge/potential
capacitors Charge storing devices, usually parallel plates.
capacitors in parallelC = C1 + C2
capacitors in series1/C = 1/C1 + 1/C2
Carnot cycles A thermal cycle comprising of isothermal and adiabatic changes.
cellsA single unit of a battery
Celsius scaleTemperature scale based on the melting point (0) an boiling point (100) of water.
Celsius scale Temperature scale based on the freezing  and boiling of water.
centre of mass  Point at which forces can be taken to act.
centripetal accelerationAcceleration towards the centre of a circle
centripetal forceForce that causes circular motion, directed towards the centre.
Cepheid variableA star with varying brightness. Time period is related to luminosity
CERNA facility near Geneva with a huge particle accelerator.
chain reactions A nuclear reaction where one fission initiates another.
Chandrasekhar limitDefines the maximum size of a white dwarf.
circular motion  frequencyNumber of complete cycles per second.
circular wavefronts Wave fronts from a point source.
closed universe A universe that stops expanding and then begins to contract.
cloud chamberParticle detector showing paths as vapour trails
coal-fired power stationsCoal is burnt to give heat used to drive a turbine
coalitionsTwo bodies join together, example of inelastic collision
coherenceLight sources with the same frequency and constant phase relationship.
coherentsimilar amplitude,same frequency constant phase difference.
colourrelated to wavelength
colour chargeThe property of quarks responsible for the strong force.
colour mixing red + green = yellow, green + blue = cyan, red + blue = magenta
comets Balls of ice with long tails orbiting the Sun.
componentsFcos(angle) and Fsin(angle)
Compton scattering Interaction between a photon and electron demonstrating particle nature of light.
concave lenses Caves go in
conductionTransfer of heat via molecular vibration.
conductors (electricity) Materials that allow the flow of charge, mainly metals as they have free electrons.
conservation of charge  Charge can not be created or destroyed.
conservation of energyEnergy can neither be created or destroyed.
conservation of momentum Provided no external forces act, the momentum of a system of bodies is always the same.
constellations Ancient civilizations playing join the dots with the stars.
constructive interference Addition of waves that are in phase.
continuous spectra Spectra produced when e.g. Solids are heated
convectionTransfer of heat in fluids due to reduced density with rise in temperature
convex lenses A converging lens, not a cave.
cornea The front surface of the eye, also acts to focus light.
cosmic background radiation Microwaves that are the result of expanding space increasing the wavelength of high energy radiation that existed in the early stages of the universe.
cosmic rays High energy particles entering the Earths atmosphere
coulomb (unit) The unit of charge.
Coulomb's law The force between two charged points is proportional to the product of their charge and inversely proportional to their separation squared.
critical angle (refraction)  Angle on incidence when angle of refraction = 90 degrees
critical damping (oscillations) System returns to equilibrium without passing through it.
critical density (universe)Density of universe that predicts that expansion stops at infinite size.
CT scans A 3D X-ray
cubicof the form y= Ax^3 +Bx^2 + Cx + D
dampingThe reduction in amplitude of an oscillator due to an opposing force.
dark energy The reason why the expansion of the universe is accelerating.
dark matter Large amounts of matter predicted to exist in the universe but not seen.
Davidson‚Germer experiment An electron scattering experiment. Evidence for the wave nature of electrons.
DCDirect Current
de Broglie hypothesisAll matter has wave like nature. 
de Broglie wavelengths h/p
decayThe changing of a nucleus by the emission of radiation.
decay chains A series of radioactive decays.
decay constants High value means rapid decay
decimal places in valuesame as uncertainty.
deep inelastic scattering Evidence for the existence of quarks.
degradation of energyEnergy becomes more spread out.
density Mass/volume
depleted uranium Non fissile Uranium
derived units Not fundamental. Like density = mass/volume
destructive interference Two waves coincide and cancel out
diffraction The spreading out of a wave as it passes through a narrow opening.
diffraction envelopeThe effect of diffraction on multiple slit interference
diffraction gratingMany equaly spaced parallel slits.
dipoles pairs of + and - charges
direct current (DC)Always in the same direction
discharge tubes Tubes of low pressure gas excited by an electric field.
dispersion The splitting up of colours by a prism.
displacement Distance moved in a particular direction. A vector quantity.
displacement‚time graphs Graph of displacement vs time.
distance Path length.
Doppler effectChange of frequency due to relative motion of source and observer.
double slit experimentPassing light through two parallel slits to give interference fringes.
drift velocityAverage velocity of electrons moving through a conductor.
dynamos A rotating coil in a magnetic field used to produce electricity.
echo Reflection of sound
EEEowSound of car passing stationary observer.
efficiencyEnergy delivered/Energy generated
Einstein rings Rings of light caused by the curvature of space - time by massive bodies.
Einstein's postulates Speed of light in a vacuum is constant and all inertial observers are the same.
Einstein‚ principle of equivalence Accelerating frames of reference are equivalent to those in gravitational fields.
elastic collisions KE and momentum conserved
elastic collisions Momentum and KE conserved.
elastic PEkx^2/2
electric charge The property responsible for the electric force.
electric currentsMovement of charge.
electric field strengthForce/charge
electric forces The force between charged bodies
electric potentialThe work done per unit charge in taking a small positive test charge from infinity to a point.
electric potential energyThe work done per unit charge in moving a small positive test charge from A to B
electric powerp = VI = I^2R = V^2/R
electromagnetic induction Generation of EMF in a conductor due to changing magnetic field.
electromagnetic wavesThe propagation of changes in electric and magnetic field
electronA negatively charged particle that can be removed from an atom. The charge carrier in metals.
electron energy levelsThe discrete energies of atomic electrons.
electron guns electrons liberated from a hot wire accelerated through a potential difference.
electron-volt (unit) The energy gained by an electron accelerated by a PD of 1 V
elements Atoms with different numbers of protons.
EM waves The propagation of changes in electric and magnetic field
emf The amount of chemical / mechanical energy converted to electrical per unit charge in a battery / generator.
emissivity Power emitted per unit area by a body / power emitted per unit area by a black body
energyThe ability to do work / Transferred when body A does work on body B.
energy density Energy per unit volume
engines Convert heat into work.
enrichmentThe process of increasing the % of fissile material in nuclear fuel.
equation of statePV = nRT
equilibrium positionThe position in which a system come to rest.
equipotential lines Lines joining points of equal potential.
equipotential surfaces Surfaces joining points of equal potential.
error barA line drawn on a point to represent uncertainties
errorsUncertainties in measurement.
escape speedSpeed required for a projectile to reach an infinite distance from a massive body.
escape speed from Earth11 km/s
evaporationLiquid changing to gas at the surface.
events Charges taking place at a given position and time.
exchange forcesForces that are the exchange of particles
explosions Two bodies pushed apart, example of inelastic collision
exponential decay equationy = mx + c
exponential equations y=e^x
fairiesSmall people with wings.
Faraday's law Induced EMF equals the rate of change of flux enclosed.
Feynman diagramsUsed to represent particle interactions, lines do not represent particle paths. Time progresses left to right (sometimes drawn with time going up)
Feynman rule 1straight lines are particles wavy lines are photons
Feynman rule 2each vertex has 2 straight one wavy line
Feynman rule 3time progresses left to right (sometimes drawn with time going up)
Feynman rule 4particles point forwards in time antiparticles backwards.
Feynman rule 5there is always one arrow entering and one leaving.
field linesShow strength (line density)  and direction (arrow) of field.
first law of thermal dynamics work done = gain in internl energy + heat lost
flat universe there is always one arrow entering and one leaving.
Fleming's left hand rule Motors: First- field, seCond - current, thuMb - motion
Fleming's right hand rule Generators: First- field, seCond - current, thuMb - motion
fluorescentA material that emits light when hit by electrons.
flux (magnetic fields) Flux density x Area
flux density Measure of the strength of magnetic field B = F/IL
forcePush and pull
force on a chargeF = Bqv
force on a wireF = BIL
forced oscillation An oscillation pushed by an external force.
frames of referenceA coordinate system an observer uses to take measurements.
free body diagrams Forces drawn that act on a body but not forces exerted by the body
free electrons Electrons free to move about in conductors.
frequencyNumber of complete cycles per second.
frequency (wave)The number of complete wavelengths passing a point per second.
frictional forceForce that opposes the relative motion of two in contact surfaces.
fringe spacing distance between bright lines in an interference pattern.
fuel densityenergy/volume
fuels Materials that can be burnt giving out heat energy.
fundamental units kg, m, A, s
g (acceleration due to gravity)9.8 m/s^2
G (universal gravitational constant)  galaxiesF = GMm/r^2
Galilean transforms Non relativistic transformations between frames of reference.
gamma radiation High energy EM radiation.
gas pressuredue to change in momentum of gas molecules hitting a wall.
gases Made of a large number of randomly moving atoms with no interatomic force.
gauge bosons Exchange particles e.g. photon
Geiger‚Marsden experiment Classic alpha scattering by Gold foil.
general relativity Relativistic theory of gravity.
generationsClassification of fundamental particles
generatorConverts KE into electrical anergy
GeoGebraMathematics application
geostationary satellites Communication satellites with 1 day time period.
global warmingRise in temperature due to enhanced greenhouse effect.
gluons Exchange particle responsible for the strong force between quarks.
GM tubeParticle detector
gradient of acceleration time graph (constant acceleration)zero
gradient of s-t graphvelocity at one moment in time.
gradient of v-t graphacceleration
gradientsChange in y / Change in x
gravitational fieldsRegion of space where a mass experiences force.
gravitational mass m = F/g
gravitational potentialWork done per unit mass taking a small test mass from infinity to a point.
gravitational potential energy Work done taking a body from infinity to a point.
gravitational red shift Increase in wavelength of receding galaxies due to Doppler shift
hadrons A particle made of quarks.
Hafele‚Keating experimentA relativistic experiment sending clocks around the Earth.
half-livesTime taken for radioactive activity to reduce by half.
harmonics (sound) Multiples of the lowest frequency standing wave formed in strings and pipes.
Harvard classification Be A Fine Girl Kiss Me. Stellar classification
heatTransferred when a hot body is in thermal contact with a cold one.
heat capacity (see specific heat capacityAmount of heat required to raise the temperature of a body by 1 K.
heat pumps Take heat from a cold body to a hot one.
Heisenberg's uncertainty principle ΔxΔp = h/4π or ΔtΔE = h/4π
hertz (unit) Cycles per second
Hertzsprung‚Russell (HR) diagramsStellar diagrams on which stars are plotted according to luminosity and temperature.
Higgs bosonFundamental particle responsible for mass.
Hooke's law Force is proportional to extension.
horizontal component (angle A measured to horizontal)FcosA
horizontal motion (projectile)constant velocity
horse power (unit) 0.75 kW
Hubble constant Constant relating recessional velocity of galaxies to distance from the Earth.
Huygens constructionA wavefront behaves as if made of an infinite umber of wavelets.
hydroelectric power PE stored in bodies of water converted to electrical energy.
hydrogenSmallest element, proton number = 1
hydrogen bomb Uses fussion to create an explosion.
hysteresis Magnetic memory
I-V graphs Current vs Voltage used to determine resistance.
ice coresSamples of ice used to measure changes in the atmosphere over time.
ideal gases Obeys the gas laws.
images Positions where rays of light cross over.
impulseChange of momentum.
Induced EMF in straight wire with velocity v perpendicular to fieldBLv
induction braking Uses induced current to oppose motion.
induction hotplates Uses changing magnetic field to excite magnetic dipoles raising temperature.
inelastic collisions Momentum but not energy conserved.
inertial frames of reference A system of coordinates in which Newton's laws of motion are obeyed.
inertial mass Ratio Force/acceleration
infrared (IR) radiation EM radiation between red and microwave.
instantaneous velocityVelocity at one moment in time.
Instantaneous velocityvery short displacement/time
insulators (electricity) Materials with no free electrons.
intensityPower per unit area. Proportional to A^2
interatomic forceForce between atoms, replulsive when close attractive when distant.
interference The addition of displacement when two waves meet.
internal energySum of KE + PE of molecules of a body.
internal resistanceResistance of internal components of a battery.
inverse square relationshipy = k/x^2
ionization Removal of electrons from an atom.
irisadjusts aperture of the eye
iris Part of the eye that controls size of apperture.
isobaric transformations Expansions / contractions where there is no exchange of heat.
isochoric transformations Constant volume expansions / contractions
isolated systems A system of bodies where no external forces act.
isothermal transformations isotherms Constant temperature expansions / contractions
isotopes Nuclei with the same proton number different neutron number.
joule (unit) Unit of energy.
katabatic winds Cold air coming down a mountain.
Kelvin scale Temperature scale based on the pressure of a fixed volume of gas.
Kepler's third law Time period of planets squared is proportional to orbital radius cubed.
kilogram Unit of mass.
kilowatt-hours Energy transferred when 1000 Watts of power is used for 1 hour.
kinetic energy (KE) The energy gained when work is done on a body to increase its speed.
Kirchhoff's 1stsum of currents into junction = sum of currents out of junction
Kirchhoff's 2ndAround a closed loop, sum of EMF's = sum of PD's
Large Hadron Collider (LHC) lasers Particle accelerator at CERN
LaserA monochromatic, parallel source of light.
latent heat Heat required to change state.
LCDs (liquid crystal displays) Use polarisation to create images.
lengthdistance between two points on an object
length contraction Reduction in length due to relative motion of object and observer.
lenses Used to bring light rays to / diverge them from  a focal point.
Lenz's lawDirection of induced current opposes change producing it.
leptons Fundamental particles with small mass.
light Visible part of EM spectrum.
light bulbs Convert electrical energy to light.
light clocks Imaginary timer used in relativity explanations.
light dependent resistors (LDRs) Semi conductor device whose resistance depends on light intensity.
light years Distance travelled by light in one year.
linearof the form y = mx +c
linear acceleratorsAccelerate charged particles in straight lines.
linear equationof the form y = mx +c
linear magnification Ratio size of image/size of object
linearizationRearranging an equation so it is in the form y = mx +c
liquid crystals Change polarisation plane unless a Pd is applied.
liquids No fixed shape but fixed volume.
logarithmic scales Divisions increase by a constant factor usually 10.
longitudinal waves Disturbance in the same direction as propagation.
Lorentz transforms Transformations that take into account the constant velocity of light.
LoudnessRelated to amplitude
luminosity Total power radiated by a star.
magnetic fieldsRegion of space where a small magnetic dipole experiences a turning force.
magnetic northEnd of a magnet that points north
magnetic resonance imaging (MRI)  magnetsUses oscillations of nuclei in magnetic fields to form medical images.
magnetic southEnd of magnet that points south
Malus's law Intenity of polarised light is proportional to the square of the cosine of difference in plane of polarisation
mass - energy equivalenceE = mc^2
mass defect Mass of pparts - mass of nucleus
mass spectrometers Separate nuclei according to mass.
measurement uncertaintythe uncertainty of the instrument and how it is used
meltdown Result of a nuclear reactor overheating.
mesons A particle made of two quarks
metre (unit) Si unit of length
Michelson‚Morley experimentShowed that the speed of light was not affected by motion relative to it's medium.
microwaves EM radiation with wavelegth of the order of mm.
Milky Way Our galaxy.
Millikan photoelectric experiment Uses stopping potential to measure KE of photo electrons.
moderatorUsed to slow down neutrons so they ate absorbed more easily e.g. Graphite
molecules Atoms held together by the interatomic force.
molecules  excitation Increasing the KE of molecules.
momentum mass x velocity
muonsA fundamental particle in the lepton family.
natural frequency Frequency of an oscillating system with no driving force.
negative accelerationchange of velocity in a negative direction
negative time Before the clock started.
negative workIf you do negative work you gain energy.
neutral currents Particle interactions with no exchange of charge.
neutrinosA group of fundamental particles with no charge and very small mass.
neutron stars Dense stars made of neutrons.
neutrons Neutral particles made of 3 quarks. Part of the nucleus.
newton (unit) SI unit of force.
Newton's 1stA body remains at rest or with constant velocity unless acted upon by an unbalanced force.
Newton's 2nd lawF = ma
Newton's 2nd law (momentm)The rate of change of momentum of a body is directly proportional to the unbalanced force acting on that body and takes place in the same direction.
Newton's 3rd LawIf body A exerts a force on body B then body B will exert and equal and opposite force on body A.
Newton's laws of motion3 laws that relate force and motion.
Newton's modelA static model of the universe.
Newton's universal law of gravitationAll point masses attract all others with a force that is proportional to the product of their mass and inversley proportional to their separation squared.
nodesPoints on a standing wave with zero amplitude.
non-ohmic conductors Conductors where current is not proportional to voltage
normal force The force perpendicular to two surfaces in contact
nuclear fissionThe splitting up of large nuclei
nuclear force The force between nucleons
nuclear fuels Fissile material used in nuclear reactors
nuclear fusionThe joining of small nuclei
nuclear magnetic resonance (NMR)Using the vibration of nuclei in magnetic fields to produce medical images
nuclear radiationParticles emitted by unstable nuclei
nuclear waste The remaining material after fission
nuclei (atoms) Heavy centre of an atom
nucleons Protons and neutrons
nuclides Different nuclear forms.
observers Experimenters committed to make measurements in a given frame of reference
Occam's razor Simple is best
ohm (unit) Unit of resistance
Ohm's lawCurrent is proportional to voltage
ohmic conductors Materials that obey Ohm's law
oil-fired power stationsUse oil to produce electricity
open universe A model of the universe with continuous expansion
Oppenheimer‚Volkoff limit The minimum size for the formation of a black hole
optical fibres Thin fibres that transmit light by total internal reflection
orbits e.g. The moon orbits the Earth, entripetal force provided by gravity
oscillating water columnsConvert wave power into electricity
oscillationA repeating cycle
oscillations  amplitudeMaximum displacement from equilibrium position
outliers (graphs) Points that don't lie on the best fit line
pair production Particle anti-particle pairs formed from photons
parabolic paths The trajectory of a projectile
parallaxShift of objects due to movement of observer
parallel circuitsComponents connected between the same points 
parsecs Distance between stars that subtends an angle of one arcsecond
particle acceleratorsDevices that accelerate charged particles
particle detectorsDevices that detect particles e.g. Geiger tube
particle modelModel that describes matter as being made of particles
Pauli exclusion principle Particles with spin half can not occupy the same energy state
Peak current and VoltageMaximum values.
pelamises A device that converts wave power into electricity
pendulums Small bodies suspended on strings
percentage uncertaintiesUncertainty divided by value as a percent
permittivity (electric fields)Constant relating electric force with charge
phase angle Angular difference between two oscillating bodies
phase difference Angular difference between two oscillating bodies
photo gates Devices used for measuring time elapsed
photodiodes Semi conducting devices that convert light into electricity
photoelectric effectEmission of electrons due to absorption of light
photons Particles of light
photosynthesisConversion of carbon dioxide and water into carbohydrates in plants using energy from the sun.
photovoltaic cells Semi conducting devices that convert light into electricity
pions Particles made of two quarks part of the meson family
pitch (sound) Perception of frequency of sound
planar wavefrontsWaves propagating in parallel lines
Planck's constantConstant relating photon energy and frequency
planets Large bodies orbiting the sun
plasmas Gases made up of ions
plum pudding model (atoms) plutonium Rutherford's model of the atom
polar satellitesSatellites that orbit the poles
polarizationRestricting the disturbance of a wave to one plane
positive accelerationchange of velocity in a positive direction
positive workIf you do positive work you lose energy
positrons The anti particle of electrons
potential difference (p.d.)The work done per unit charge in moving a small positive test charge between two points 
potential dividersSeries resistors used to produce a variable potential difference
potential energy (PE) The work done in placing a body in a position
potential gradientchange in V / change in x
potential wells  A minimum in potential energy
Pound‚Rebka experiment Measured the change in frequency when EM radiation travelled vertically
power Energy per unit time
power lines Cables used to trsnsmit electrical energy
power loss (electricity) Energy loss in power lines.
power stations Generate electrical energy.
precise measurements close to each other 
pressureForce per unit area
primary colours Red, green, blue
probability function Function that gives the probability of the position of a particle
probability waves A wave function that gives the probability of the position of a particle
projectile motionMotion of a particle moving freely in a uniform gravitational field
proper length The length of an object measured by an observer at rest relative to it
proper time The time of an event measured by a clock at rest relative to the event
proportional relationshipof the form y = mx
proton-proton chains The process of fusion producing energy in the sun
protons Positive particles made of three quarks present in the nucleus
protostars The early stage in the life of a star
pupilapperture of the eye
PV diagramsPressure-volume graphs
Pythagoras' theorem Square of hypotenuse is equal to the sum of the square of the other two sides
quantized energy For example electrons can only exist in certain energy levels
quantum chromodynamics (QCD)The theory explaining the force between quarks
quantum model Atomic model describing the electron energies in terms of a probability function
quantum numbersNumbers defining electron energy states
quantum tunnelingA particle can get past a barrier without climbing over it.
quark confinement The reason why quarks can not exist alone
quarksFundamental particles that make up baryons and mesons
radians Measurement of angle. Arc length divided by radius
radiationTransfer of heat via electromagnetic waves.
radiation  absorption spectra Produced when white light is passed through a low pressure gas
radiation therapyUsing radioactive isotopes to kill cancer cells
radiation-dominated universe A time when universe was dominated by photons
radio wavesLong-wavelength EM radiation
radioactive datingA way of using the decay of radioactive isotopes to determine age
radioactive isotopesNuclei with the same proton number different neutron number.
random errors errors resulting from uncertainties in measuring device or conditions.
rangehorizontal distance travelled by projectile
rate of changedx/dt
Rayleigh criterionTwo objects are resolved if the first minimum in the diffraction pattern of one coincides with the principal maxima of the other
rays (waves) Lines drawn at right angles to wavefronts
real images Points where rays cross
red giants Stars at the end of their life cycle
red shift Shift in wavelength due to the recession of sources of light
reflection What happens when light hits a mirror
refraction Change of direction of a wave when passing through a boundary between two media
refractive indices Sine of the angle of instance over angle of refraction
refrigerators Use thermic cycles to transfer energy from hot bodies to cold
relative atomic massThe mass of an atom relative to 1/12 the mass of a carbon 12 atom
relative velocity The velocity measured by a moving observer
resistanceThe ratio of potential difference / current
resistivity The resistance of a cubic meter of material
resistors Devices that reduce the current in a circuit
resolutionThe ability to distinguish two point objects
resolvanceThe ability to resolve spectral lines
resonance When an oscillating system is made to vibrate at its own natural frequency
resonance curves A graph of amplitude against forcing frequency
resultant force The vector sum of all forces acting on a body
retinalight sensitive part of the eye
right hand grip rulethumb in direction of current fingers curl in direction of field
root mean square current and voltage (rms) The root of the mean of the squares. Gives same power as DC value
rotation Caused when a force does not act through the centre of mass
Rutherford modelPlum pudding model
samplingThe rate of taking measurements by a digital device
Sankey diagrams Flow diagrams
satellitesBodies that orbid the earth
scalars Quantities with magnitude but no direction
second lawIn any interaction the entropy will always increase
seconds (time) SI unit of time
serendipityLuck
series circuits Components connected in a line
SHM KEMax at equilibrium position
SHM PEMax at max displacement
SHM toal energyConstant = PE + KE
SI unitsInternational system of units
sig figs in uncertainty1 or 2
simple harmonic motion (SHM)When force is proportional to displacement from a fixed point and always acts towards that point
simultaneity Events taking place at the same time are not at the same time for all observers
small angle approx.SinA = A in radians
Snell's law Sine angle of incidence / Sine angle of refraction = Constant
solar constant Intensity of solar radiation incident at the earth
solar energy Using energy from the sun to produce electricity
solenoids Coils where the windings are side by side
sonic boomA bang caused by the accumulation of sound when a body travels at the speed of sound.
sonometerA single stringed musical instrument.
soundpropagation of changes in pressure.
special relativityThe study of relativity applied to inertial frames of reference.
specific energyenrgy/mass
specific heat capacityThe amount of heat required to raise the temperature of 1kg of a substance by 1 K.
specific latent heat (see latent heat)The amount of heat required to change the state of 1 kg of a substance without change in temperature.
spectrometerA device used to view spectra
Spectrum of lightRanges from red (low frequency long wavelength) to blue (high frequency, short wavelength)
speed Distance travelled / time
speed of light in a vacuumc = 300,000,000 m/s
spherical aberration The outer rays passing through a convex lens are deviated more than the inner ones.
spinA propety of particles, can be 1/2, 1 or 0. can align or not align 1/2 + 1/2 = 1 or 0
spin (particles) A property of all subatomic particles
spring constantForce/extension
standing wavesFormed when a wave interferes with its reflection.
states of matter solid, liquid and gas
Stefan‚Boltzmann law Radiated power per unit area is proportional to thhe 4th power of absolute temperature
stellar clusters Groups of stars.
step indexed fibres Optical fibres made of layers with decreasing refractive index.
stimulated emission When the emmission of a photon is initiated by a photon on the same frequency.
stopping (lenses) Applying a small aperture to a lens to reduce spherical abberation.
straight line graphs y = mx + c
strangeness A property of subatomic particles expressed as a quantum number.
stringed instruments instruments with stretched strings e.g. Guitar
strong force/interactions The force between quarks.
subsidiary maximaSmall maxima between pricipal maxima. (number of slits - 2)
supernovas Exploding stars.
superposition Vector addition of wave displacement
suvat 1 (uvat)a =(v - u)/t
suvat 2 (suvt)s = (u + v)t/2
suvat 3 (suat)s =ut + at^2/2
suvat 4 (suva)v^2 = u^2 + 2as
suvat equations A set of equations used to solve problems involving motion with constant acceleration.
systematic errorsWhen the same error occurs in all measurements.
temperatureDefines the direction of heat flow. Related to average KE of molecules.
tension When a force is applied via a string.
tesla (unit) Unit of magnetic flux density.
thermalRefers to systems where there is exchange of heat.
thermal capacity The amount of heat required to raise the temperature of a body by 1 K.
thermal equilibriumWhen there is no flow of heat between two bodies in contact.
thermodynamic cycles A series of transformations that begin and end at the same state.
threshold frequency The minimum frequency require for the emission of photo electrons.
tidal power Electrical energy generated from the flow of tides.
time periodtime for one revolution
total internal reflection occurs when light is incident on a boundary to a less dense medium.
totally inelastic collisionsWhen bodies stick together.
trajectorypath of a particle
transformersCoils with shared magnetic field. Np/Ns = Vp/Vs
translational equilibriumWhen the forces acting on a body add uo to give zero.
transmutationsWhen a nucleus changes to another
transverse waves When the direction of disturbance is perpendicular to the direction of propagation.
turbineCreates rotation from the KE in moving fluids.
twin paradox One twin takes a high speed journey and returns to Earth younger
ultrasoundHigh frequency, inaudible sound.
ultraviolet (UV) light uncertaintyHigh freqency EM radiation, just outside the visible spectrum.
uncertaintyHow well you can define a quantity.
uncertainty in a range of values(max-min)/2
unified mass units  1/12 of the mass of a carbon 12 atom.
uniform electric field strengthE=V/d
uniform fields Parallel, equally spaced field lines.
unstable nuclei Nuclei that emit radiation changing into something with higher BE.
upthrust Same as buoyancy.
variable stars Stars with varying brightness.
vector additionnose to tail, resultant is line joining free nose to tail.
vectorsQuantities with magnitude and direction e.g. Force
velocityDisplacement / time
velocity‚time graphs Linear when acceleration is constant.
vernier caliperA sliding scale used to measure small lengths accurately
vertical component (angle A measured to horizontal)FsinA
vertical motion (projectile)constant negative acceleration
Video analysisUsing LoggerPro to analyse motion in a video.
volt (unit) Unit of potential. Same as J/C
voltmeters Instrument for measuring PD. Ideally have infinite resistance.
volume of a cubeL^3
volume of a sphere4/3 πr^3
W boson Exchange particle in weak interactions
watt (unit) SI unit of power J/s
wave particle dualityThe theory that the position of particles given by a wave function.
wave speed frequency x wavelength
wavefrontsLines joining points on a wave that are in phase.
wavelength The distance between two consecutive, in phase points on a wave.
waves A physical phenomenon that diffracts and interferes
weak force/interactions Interactions involving neutrinos
weight (gravitational force) Force of attraction between a body and the Earth.
weightlessness Apparent lack of weight in free falling frames of reference.
white dwarves Small hot stars. After the main sequence.
white light a mixture of all the colours in he rainbow.
Wien's law The peak wavelength in the black body spectrum is inversely proportional to absolue temperature.
wind instruments Make use of standing waves in pipes.
wind turbines Convert KE in wind into electrical energy.
wire chambers A particle detector.
work (energy transfer)Force x distance moved in direction of force.
work function (photoelectric effect) Minimum energy required to liberate photo electrons.
X-rays High frequency EM radiation.
X-rays diffraction The result of passing X-rays through crystals.
y interceptWhere a line crosses the y axis-
zinc plate experiment  A demonstration of the photoelectric effect.
zinc sulphide A material used in the screens of electron tubes.
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