| absolute uncertainties | Plus or minus the uncertainty |
| absolute zero | The lowest temperature possible zero K |
| acceleration | The rate of change of velocity |
| accurate measurement | close to the accepted value |
| activity | The rate of decay |
| adiabatic transformations | No exchange of heat |
| air resistance | The force of air opposing motion |
| air wedge interference | The interference of light reflected off to angled glass plates |
| albedo | The ratio of scattered light to incident light |
| Algodoo | application 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 |
| Ampere | 1A causes a force of 2 x 10^-7 N between to long conductors 1 m apart in a vacuum |
| amplitude | Height 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 displacement | The angle swept out by the radius. |
| angular frequency | The angle swept out per unit time. |
| Angular momentum | mvr |
| angular velocity | The angle swept out per unit time |
| annihilation | particle + antiparticle = energy but no mass |
| antimatter | Matter made up of anti particles |
| antineutrinos | Antiparticle of neutrino |
| antinodes | Positions 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 graph | change in velocity |
| area under force - time graph | Work |
| area under force distance graph | Work |
| area under graph | area under the line |
| area under v-t graph | displacement |
| 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 lattice | A 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. |
| attenuation | Reduction in amplitude |
| Aurora Borealis | Glow in the night sky in the north due to the interaction betweencharged particles and the atmosphere |
| average value of sine function | 00-Jan |
| average velocity | Displacement / time |
| average velocity | displacement/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 line | A line drawn as close as possible to the data points |
| beta particles | An electron formed when a neutron changes to a proton. |
| Big Bang | A model for the start of the universe. |
| big crunch | A model for the end of the universe. |
| binary stars | Pairs 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 rods | Absorb neutrons slowing down the chain reaction |
| Brownian motion | The randon motion of smoke particles knocked about by air molecules. |
| buoyancy | Upward force due to displacement of fluid. |
| capacitance | charge/potential |
| capacitors | Charge storing devices, usually parallel plates. |
| capacitors in parallel | C = C1 + C2 |
| capacitors in series | 1/C = 1/C1 + 1/C2 |
| Carnot cycles | A thermal cycle comprising of isothermal and adiabatic changes. |
| cells | A single unit of a battery |
| Celsius scale | Temperature 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 acceleration | Acceleration towards the centre of a circle |
| centripetal force | Force that causes circular motion, directed towards the centre. |
| Cepheid variable | A star with varying brightness. Time period is related to luminosity |
| CERN | A facility near Geneva with a huge particle accelerator. |
| chain reactions | A nuclear reaction where one fission initiates another. |
| Chandrasekhar limit | Defines the maximum size of a white dwarf. |
| circular motion frequency | Number 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 chamber | Particle detector showing paths as vapour trails |
| coal-fired power stations | Coal is burnt to give heat used to drive a turbine |
| coalitions | Two bodies join together, example of inelastic collision |
| coherence | Light sources with the same frequency and constant phase relationship. |
| coherent | similar amplitude,same frequency constant phase difference. |
| colour | related to wavelength |
| colour charge | The 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. |
| components | Fcos(angle) and Fsin(angle) |
| Compton scattering | Interaction between a photon and electron demonstrating particle nature of light. |
| concave lenses | Caves go in |
| conduction | Transfer 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 energy | Energy 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 |
| convection | Transfer 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 |
| cubic | of the form y= Ax^3 +Bx^2 + Cx + D |
| damping | The 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. |
| DC | Direct Current |
| de Broglie hypothesis | All matter has wave like nature. |
| de Broglie wavelengths | h/p |
| decay | The 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 value | same as uncertainty. |
| deep inelastic scattering | Evidence for the existence of quarks. |
| degradation of energy | Energy 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 envelope | The effect of diffraction on multiple slit interference |
| diffraction grating | Many 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 effect | Change of frequency due to relative motion of source and observer. |
| double slit experiment | Passing light through two parallel slits to give interference fringes. |
| drift velocity | Average velocity of electrons moving through a conductor. |
| dynamos | A rotating coil in a magnetic field used to produce electricity. |
| echo | Reflection of sound |
| EEEow | Sound of car passing stationary observer. |
| efficiency | Energy 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 PE | kx^2/2 |
| electric charge | The property responsible for the electric force. |
| electric currents | Movement of charge. |
| electric field strength | Force/charge |
| electric forces | The force between charged bodies |
| electric potential | The work done per unit charge in taking a small positive test charge from infinity to a point. |
| electric potential energy | The work done per unit charge in moving a small positive test charge from A to B |
| electric power | p = VI = I^2R = V^2/R |
| electromagnetic induction | Generation of EMF in a conductor due to changing magnetic field. |
| electromagnetic waves | The propagation of changes in electric and magnetic field |
| electron | A negatively charged particle that can be removed from an atom. The charge carrier in metals. |
| electron energy levels | The 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 |
| energy | The ability to do work / Transferred when body A does work on body B. |
| energy density | Energy per unit volume |
| engines | Convert heat into work. |
| enrichment | The process of increasing the % of fissile material in nuclear fuel. |
| equation of state | PV = nRT |
| equilibrium position | The 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 bar | A line drawn on a point to represent uncertainties |
| errors | Uncertainties in measurement. |
| escape speed | Speed required for a projectile to reach an infinite distance from a massive body. |
| escape speed from Earth | 11 km/s |
| evaporation | Liquid changing to gas at the surface. |
| events | Charges taking place at a given position and time. |
| exchange forces | Forces that are the exchange of particles |
| explosions | Two bodies pushed apart, example of inelastic collision |
| exponential decay equation | y = mx + c |
| exponential equations | y=e^x |
| fairies | Small people with wings. |
| Faraday's law | Induced EMF equals the rate of change of flux enclosed. |
| Feynman diagrams | Used to represent particle interactions, lines do not represent particle paths. Time progresses left to right (sometimes drawn with time going up) |
| Feynman rule 1 | straight lines are particles wavy lines are photons |
| Feynman rule 2 | each vertex has 2 straight one wavy line |
| Feynman rule 3 | time progresses left to right (sometimes drawn with time going up) |
| Feynman rule 4 | particles point forwards in time antiparticles backwards. |
| Feynman rule 5 | there is always one arrow entering and one leaving. |
| field lines | Show 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 |
| fluorescent | A 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 |
| force | Push and pull |
| force on a charge | F = Bqv |
| force on a wire | F = BIL |
| forced oscillation | An oscillation pushed by an external force. |
| frames of reference | A 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. |
| frequency | Number of complete cycles per second. |
| frequency (wave) | The number of complete wavelengths passing a point per second. |
| frictional force | Force that opposes the relative motion of two in contact surfaces. |
| fringe spacing | distance between bright lines in an interference pattern. |
| fuel density | energy/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) galaxies | F = GMm/r^2 |
| Galilean transforms | Non relativistic transformations between frames of reference. |
| gamma radiation | High energy EM radiation. |
| gas pressure | due 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. |
| generations | Classification of fundamental particles |
| generator | Converts KE into electrical anergy |
| GeoGebra | Mathematics application |
| geostationary satellites | Communication satellites with 1 day time period. |
| global warming | Rise in temperature due to enhanced greenhouse effect. |
| gluons | Exchange particle responsible for the strong force between quarks. |
| GM tube | Particle detector |
| gradient of acceleration time graph (constant acceleration) | zero |
| gradient of s-t graph | velocity at one moment in time. |
| gradient of v-t graph | acceleration |
| gradients | Change in y / Change in x |
| gravitational fields | Region of space where a mass experiences force. |
| gravitational mass | m = F/g |
| gravitational potential | Work 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 experiment | A relativistic experiment sending clocks around the Earth. |
| half-lives | Time 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 |
| heat | Transferred when a hot body is in thermal contact with a cold one. |
| heat capacity (see specific heat capacity | Amount 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) diagrams | Stellar diagrams on which stars are plotted according to luminosity and temperature. |
| Higgs boson | Fundamental 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 construction | A wavefront behaves as if made of an infinite umber of wavelets. |
| hydroelectric power | PE stored in bodies of water converted to electrical energy. |
| hydrogen | Smallest 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 cores | Samples 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. |
| impulse | Change of momentum. |
| Induced EMF in straight wire with velocity v perpendicular to field | BLv |
| 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 velocity | Velocity at one moment in time. |
| Instantaneous velocity | very short displacement/time |
| insulators (electricity) | Materials with no free electrons. |
| intensity | Power per unit area. Proportional to A^2 |
| interatomic force | Force between atoms, replulsive when close attractive when distant. |
| interference | The addition of displacement when two waves meet. |
| internal energy | Sum of KE + PE of molecules of a body. |
| internal resistance | Resistance of internal components of a battery. |
| inverse square relationship | y = k/x^2 |
| ionization | Removal of electrons from an atom. |
| iris | adjusts 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 1st | sum of currents into junction = sum of currents out of junction |
| Kirchhoff's 2nd | Around a closed loop, sum of EMF's = sum of PD's |
| Large Hadron Collider (LHC) lasers | Particle accelerator at CERN |
| Laser | A monochromatic, parallel source of light. |
| latent heat | Heat required to change state. |
| LCDs (liquid crystal displays) | Use polarisation to create images. |
| length | distance 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 law | Direction 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. |
| linear | of the form y = mx +c |
| linear accelerators | Accelerate charged particles in straight lines. |
| linear equation | of the form y = mx +c |
| linear magnification | Ratio size of image/size of object |
| linearization | Rearranging 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. |
| Loudness | Related to amplitude |
| luminosity | Total power radiated by a star. |
| magnetic fields | Region of space where a small magnetic dipole experiences a turning force. |
| magnetic north | End of a magnet that points north |
| magnetic resonance imaging (MRI) magnets | Uses oscillations of nuclei in magnetic fields to form medical images. |
| magnetic south | End 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 equivalence | E = mc^2 |
| mass defect | Mass of pparts - mass of nucleus |
| mass spectrometers | Separate nuclei according to mass. |
| measurement uncertainty | the 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 experiment | Showed 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. |
| moderator | Used 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 |
| muons | A fundamental particle in the lepton family. |
| natural frequency | Frequency of an oscillating system with no driving force. |
| negative acceleration | change of velocity in a negative direction |
| negative time | Before the clock started. |
| negative work | If you do negative work you gain energy. |
| neutral currents | Particle interactions with no exchange of charge. |
| neutrinos | A 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 1st | A body remains at rest or with constant velocity unless acted upon by an unbalanced force. |
| Newton's 2nd law | F = 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 Law | If 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 motion | 3 laws that relate force and motion. |
| Newton's model | A static model of the universe. |
| Newton's universal law of gravitation | All point masses attract all others with a force that is proportional to the product of their mass and inversley proportional to their separation squared. |
| nodes | Points 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 fission | The splitting up of large nuclei |
| nuclear force | The force between nucleons |
| nuclear fuels | Fissile material used in nuclear reactors |
| nuclear fusion | The joining of small nuclei |
| nuclear magnetic resonance (NMR) | Using the vibration of nuclei in magnetic fields to produce medical images |
| nuclear radiation | Particles 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 law | Current is proportional to voltage |
| ohmic conductors | Materials that obey Ohm's law |
| oil-fired power stations | Use 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 columns | Convert wave power into electricity |
| oscillation | A repeating cycle |
| oscillations amplitude | Maximum 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 |
| parallax | Shift of objects due to movement of observer |
| parallel circuits | Components connected between the same points |
| parsecs | Distance between stars that subtends an angle of one arcsecond |
| particle accelerators | Devices that accelerate charged particles |
| particle detectors | Devices that detect particles e.g. Geiger tube |
| particle model | Model 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 Voltage | Maximum values. |
| pelamises | A device that converts wave power into electricity |
| pendulums | Small bodies suspended on strings |
| percentage uncertainties | Uncertainty 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 effect | Emission of electrons due to absorption of light |
| photons | Particles of light |
| photosynthesis | Conversion 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 wavefronts | Waves propagating in parallel lines |
| Planck's constant | Constant 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 satellites | Satellites that orbit the poles |
| polarization | Restricting the disturbance of a wave to one plane |
| positive acceleration | change of velocity in a positive direction |
| positive work | If 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 dividers | Series resistors used to produce a variable potential difference |
| potential energy (PE) | The work done in placing a body in a position |
| potential gradient | change 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 |
| pressure | Force 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 motion | Motion 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 relationship | of 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 |
| pupil | apperture of the eye |
| PV diagrams | Pressure-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 numbers | Numbers defining electron energy states |
| quantum tunneling | A particle can get past a barrier without climbing over it. |
| quark confinement | The reason why quarks can not exist alone |
| quarks | Fundamental particles that make up baryons and mesons |
| radians | Measurement of angle. Arc length divided by radius |
| radiation | Transfer of heat via electromagnetic waves. |
| radiation absorption spectra | Produced when white light is passed through a low pressure gas |
| radiation therapy | Using radioactive isotopes to kill cancer cells |
| radiation-dominated universe | A time when universe was dominated by photons |
| radio waves | Long-wavelength EM radiation |
| radioactive dating | A way of using the decay of radioactive isotopes to determine age |
| radioactive isotopes | Nuclei with the same proton number different neutron number. |
| random errors | errors resulting from uncertainties in measuring device or conditions. |
| range | horizontal distance travelled by projectile |
| rate of change | dx/dt |
| Rayleigh criterion | Two 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 mass | The mass of an atom relative to 1/12 the mass of a carbon 12 atom |
| relative velocity | The velocity measured by a moving observer |
| resistance | The ratio of potential difference / current |
| resistivity | The resistance of a cubic meter of material |
| resistors | Devices that reduce the current in a circuit |
| resolution | The ability to distinguish two point objects |
| resolvance | The 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 |
| retina | light sensitive part of the eye |
| right hand grip rule | thumb 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 model | Plum pudding model |
| sampling | The rate of taking measurements by a digital device |
| Sankey diagrams | Flow diagrams |
| satellites | Bodies that orbid the earth |
| scalars | Quantities with magnitude but no direction |
| second law | In any interaction the entropy will always increase |
| seconds (time) | SI unit of time |
| serendipity | Luck |
| series circuits | Components connected in a line |
| SHM KE | Max at equilibrium position |
| SHM PE | Max at max displacement |
| SHM toal energy | Constant = PE + KE |
| SI units | International system of units |
| sig figs in uncertainty | 1 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 boom | A bang caused by the accumulation of sound when a body travels at the speed of sound. |
| sonometer | A single stringed musical instrument. |
| sound | propagation of changes in pressure. |
| special relativity | The study of relativity applied to inertial frames of reference. |
| specific energy | enrgy/mass |
| specific heat capacity | The 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. |
| spectrometer | A device used to view spectra |
| Spectrum of light | Ranges from red (low frequency long wavelength) to blue (high frequency, short wavelength) |
| speed | Distance travelled / time |
| speed of light in a vacuum | c = 300,000,000 m/s |
| spherical aberration | The outer rays passing through a convex lens are deviated more than the inner ones. |
| spin | A 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 constant | Force/extension |
| standing waves | Formed 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 maxima | Small 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 errors | When the same error occurs in all measurements. |
| temperature | Defines 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. |
| thermal | Refers 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 equilibrium | When 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 period | time for one revolution |
| total internal reflection | occurs when light is incident on a boundary to a less dense medium. |
| totally inelastic collisions | When bodies stick together. |
| trajectory | path of a particle |
| transformers | Coils with shared magnetic field. Np/Ns = Vp/Vs |
| translational equilibrium | When the forces acting on a body add uo to give zero. |
| transmutations | When a nucleus changes to another |
| transverse waves | When the direction of disturbance is perpendicular to the direction of propagation. |
| turbine | Creates rotation from the KE in moving fluids. |
| twin paradox | One twin takes a high speed journey and returns to Earth younger |
| ultrasound | High frequency, inaudible sound. |
| ultraviolet (UV) light uncertainty | High freqency EM radiation, just outside the visible spectrum. |
| uncertainty | How 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 strength | E=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 addition | nose to tail, resultant is line joining free nose to tail. |
| vectors | Quantities with magnitude and direction e.g. Force |
| velocity | Displacement / time |
| velocity‚time graphs | Linear when acceleration is constant. |
| vernier caliper | A sliding scale used to measure small lengths accurately |
| vertical component (angle A measured to horizontal) | FsinA |
| vertical motion (projectile) | constant negative acceleration |
| Video analysis | Using 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 cube | L^3 |
| volume of a sphere | 4/3 πr^3 |
| W boson | Exchange particle in weak interactions |
| watt (unit) | SI unit of power J/s |
| wave particle duality | The theory that the position of particles given by a wave function. |
| wave speed | frequency x wavelength |
| wavefronts | Lines 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 intercept | Where 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. |
