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230 Cards in this Set
- Front
- Back
Absolute refractive index |
The ratio between the speed of light in a vacuum and the speed of light in a material |
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Absolute uncertainty |
The uncertainty of a measurement given as a fixed quantity |
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Absorption (fibre optics) |
Where some of the energy of a fire-optic signal is absorbed by the material of the optical fibre |
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Acceleration |
The rate of change of velocity |
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Accurate result |
An accurate result is really close to the true answer |
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Alpha decay |
A type of decay in which an unstable nucleus of an atom emits an alpha particle |
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Alpha particle |
A particle made up of two protons and two neutrons (a helium nucleus) |
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Ammeter |
A component used to measure the current flowing through a circuit |
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Amplitude |
The maximum displacement of a wave, i.e. the distance from the undisturbed position to a crest or trough |
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Angle of incidence |
The angle that incoming light makes with the normal of a boundary |
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Angle of regraction |
The angle that refracted light makes with the normal of a boundary |
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Annihilation |
The process by which a particle and its antiparticle meet and their mass gets converted to energy in the form of pair of gamma ray photons |
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Anomolous result |
A result that doesn't fit in with the pattern of the other results in a set of data |
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Antimatter |
The name given to all antiparticles |
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Antineutrino |
The antiparticle of a neutrino |
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Antineutron |
The antiparticle of a neutron |
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Antinode |
A point of maximum amplitude on a stationary wave |
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Antiparticle |
A particle with the same rest mass and energy as its corresponding particle, but equal and opposite charge |
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Antiproton |
The antiparticle of a proton |
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Atom |
A particle made up of protons and neutrons in a central nucleus, and electrons orbiting the nucleus |
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Atomic number |
The number of protons in an atom of an element |
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Average velocity |
The change in displacement of an object divivded by the time taken |
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Baryon |
A type of hadron made up of three quarks. For example, protons and neutrons |
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Baryon number |
The number of baryons in a particle |
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Beta-minus decay |
A type of decay in which an unstable nucleus of an atom emits a beta-minus particle (an electron) and an antineutrino |
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Beta-plus decay |
A type of decay in which an unstable nucleus of an atom emits a beta-plus particle (a positron) and a neutrino |
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Breaking stress |
The lowest stress that's big enough to break a material |
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Brittle |
A brittle material doesn't reform plastically, but snaps when the stress on it reaches a certain point |
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Brittle fracture |
When a stress applied to a brittle material causes tiny cracks at the material's surface to get bigger until the material breaks completely |
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Calibration |
Marking a scale on a measuring instrument or checking a scale by measuring a known value |
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Categoric data |
Data that can be sorted into categories |
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Centre of mass |
The point which you can consider all of an object's weight to act through |
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Circuit symbol |
A pictorial representation of an electrical component |
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Cloud chamber |
A chamber filled with a vapour which is used to track the motion of charged particles |
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Coherent |
Sources (or waves) that have the same wavelength and frequency and a fixed phase difference between them are coherent |
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Compressive force |
A force which squashes something |
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Conservation of energy (princriple of) |
Energy cannot be created or destroyed. It can be transferred from one form to another, but the total amount of energy in a closed system will not change |
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Constructive interference |
When two waves interfere to make a wave with a larger displacement |
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Continuous data |
Data that can have any value of a scale |
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Control variable |
A variable that is kept constant in an experiment |
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Cosmic ray showers |
Lots of high-energy particles that are produced from cosmic rays interacting with molecules in the atmosphere |
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Cosmic rays |
Raditation in the form of charged particles that come from space and hit Earth |
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Coulomb (C) |
A unit of charge. One coulomb is the amount of charge that passes in 1 second when the current is 1 ampere |
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Couple |
A pair of forces of equal size which act parallel to each other but in opposite directions |
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Critical angle |
The angle of incidence at which the angle of refraction is 90degrees |
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Crumple zone |
Part of a car or other vehicle designed to deform plastically in a crash so less energy is transferred to the people inside |
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Current |
The rate of flow of charge in a circuit. Measured in amperes (A) |
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Density |
The mass per unit volume of a material or object |
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Dependent variable |
The variable that you measure in an experiment |
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Destructive interference |
When two waves interfere to make a wave with a reduced displacement |
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Diffraction |
When waves spread out as they pass through a narrow gap or go around obstacles |
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Diffraction grating |
A slide or other thin object that contains lots of equally spaced slits, very close together, used to show diffraction patterns of waves |
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Diode |
A component designed to allow current to flow in one direction only |
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Discrete data |
Data that can only take certain values |
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Dispersion |
A form of signal degradation that causes pulse broadening of a fibre-optic signal as it travels |
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Displacement |
How far an objects has travelled from its starting point in a given direction. In the case of a wave, it is the distance a point has moved from its undisturbed position |
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Drag |
Friction caused by a fluid (gas or liquid) |
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Efficiency |
The ratio of useful energy given out by a machine to the amount of energy put into the machine |
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Elastic |
An elastic material returns to its original shape/length once the forces acting on it are removed |
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Elastic limit |
The force (or stress) beyond which a material will be permanently stretched |
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Elastic strain energy |
The energy stored in a stretched material |
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Electromagnetic force |
A fundamental force that causes interactions between charged particles. Vitual photons are the exchange particle |
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Electromagnetic spectrum |
A continuous spectrum of all the possible frequencies of electromagnetic radiation |
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Electromotive force (e.m.f) |
The amount of electrical energy a power supply transfers to each coulomb of charge |
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Electron |
A lepton with a relative charge of -1 and a relative mass of 0.0005. Sometimes called a beta-minus particle |
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Electron capture |
The process of a proton-rich nucleus capturing an electron to turn a proton into a neutron, emitting a neutrino |
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Electron-proton collision |
The process of an electron colliding with a proton and producing a neutron and a neutrino |
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Electron volt |
The kinetic energy carried by an electron after it has been accelerated from rest through a potential difference of one volt |
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Equilibrium |
An object is in equilibrium if all the forces acting on it cancel each other out |
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Evidence |
Valid data arising from an experiment, which can be used to support a conclusion |
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Exchange particle |
A virtual particle which allows forces to act in a particle interaction. They are also known as guage bosons |
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Excitation |
The movement of an electron to a high energy level in an atom |
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Fair test |
An experiment in which all variables are kept constant apart from the independent and dependent variables |
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First harmonic |
The lowest frequency at which a stationary wave is formed where the wavelength is double the length of the vibrating column |
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Fractional uncertainty |
The uncertainty given as a fraction of the measurement taken |
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Freefall |
The motion of an object undergoing an acceleration of g |
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Frequency |
The number of whole wave cycles (oscillations) per second passing a given point. Or the number of whole waves cycles (oscillations) given out from a source per second |
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Friction |
A force that opposes motion. It acts in the opposite direction to the motion. It arises when two objects are moving past each other, or an objects is moving through a fluid |
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Fundamental particle |
A particle which cannot be split up into smaller particles |
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Guage boson |
A virtual particle which allows forces to act in a particle interaction. They are also known as exchange particles |
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Geiger counter |
A device to measure the amount of ionising radiation |
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Gravitational force |
A fundamental force which causes attraction between objects with a force proportional to their mass |
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Gravitational potential energy |
The energy an object gains when lifted up in a gravitational field, due to its position |
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Ground state |
The lowest energy level of an atom or the lowest energy level for an electron in an atom |
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Hadron |
A particle made up of quarks that is affected by the strong nuclear force |
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Hooke's law |
The extension of a stretched force is no longer proportional to extension. Also known as the limit of proportionality |
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Hypothesis |
A suggested explanation for a fact or observation |
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I-v characteristic |
A graph which shows how the current flowing through a component changes as the potential difference across it is increased |
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Impulse |
The impulse acting on an object is equal to the change in momentum of the object |
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Independent variable |
he variable that you change in an experiment |
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Instantaneous velocity |
The velocity of an objects at a particular moment in time |
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Intensity (of light) |
The power per unit area |
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Interference |
The superposition of two or more waves |
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Internal resistance |
The resistance created in a power source when electrons collide with atoms inside the power source and lose energy |
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Ionisation |
The process where an electron is removed from (or added to) an atom |
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Ionisation energy |
The energy required to remove an electron from an atom in its ground state |
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Isotope |
One of two or more of an element with the same proton number but a different nucleon number |
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Isotopic data |
The relative amounts of isotopes in a substance |
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Kinetic energy |
The energy possessed by a moving object due to it movement |
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Lepton |
A fundamental particle that is not affected by the strong nuclear force |
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Lepton number |
The number of leptons in a particle. Lepton number is counted separately for different types of leptons |
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Lever |
A structure made of a rigid object rotating around a pivot, in which an effort force works against a load force |
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Lift |
An upwards force on an object moving through a fluid |
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Light-dependent resistor (LDR) |
A resistor with a resistance that depends on the intensity of light falling on it. The resistance decreases with increasing light intensity |
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Limit of proportionality |
The point beyond which force is no longer proportional to extension. Also known as Hooke's Law limit |
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Line absorption spectrum |
A light spectrum with dark lines corresponding to different wavelengths of light that have been absorbed |
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Line emission spectrum |
A spectrum of bright lines on a dark background corresponding to different wavelengths of light that have been emitted from a light source |
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Line spectrum |
A pattern of lines produced by photons being emitted or absorbed by electrons moving between energy levels in an atom |
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Longitudinal wave |
A wave in which the displacement of particles/fields (vibrations) is in the direction of energy propagation |
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Lost volts |
The energy wasted per coulomb overcoming the internal resistance of a power source |
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Mass |
The amount of matter in an object |
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Mass number |
The number of nucleons in an atom of an element |
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Material dispersion |
Dispersion caused by different wavelengths of light travelling at different speeds through the material of an optical fibre |
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Matter |
The name given to all particles |
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Maximum (interference) |
A point in an interference pattern where the intensity is locally brightest (a location of constructive interference) |
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Meson |
A type of hadron made up of a quark and an antiquark. For example, pions and kaons |
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Minimum (interference) |
A point in an interference pattern where the intensity is locally lowest (a location of destructive interference)
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Modal dispersion |
Dispersion caused by reflected light taking paths of different lengths in an optical fibre |
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Moment |
The turning effect of a force around a turning point |
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Moment of a couple |
The moment caused by two equal forces acting parallel to each other but in opposite directions around a turning point |
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Momentum |
The momentum of an object is the product of its mass and velocity |
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Monochromatic |
A light source that is all of the same wavelength (or frequency) |
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Neutrino |
A lepton with (almost) zero mass and zero charge |
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Neutron |
A neutral baryon with a relative mass of 1 |
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Newton's 1st Law of Motion |
The velocity of an object will not change unless a resultant force acts on it |
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Newton's 2nd Law of Motion |
The acceleration of an object is proportional to the resultant velocity acting on it |
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Newton's 3rd Law of Motion |
If an object A exerts a force on object B, then object B exerts anequal and opposite force on object A |
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Node |
A point of minimum amplitude on a stationary wave |
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Nuclear decay |
The process of an unstable nucleus emitting particles in order to become more stable |
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Nucleon |
A particle in the nucleus of an atom (which can be a proton or a neutron) |
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Nucleon number |
The number of nucleons in an atom of an element |
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Nucleus |
The centre of an atom, containing protons and neutrons |
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Nuclide notation |
A notation that tells you the nucleon number, A and proton number, Z, of an element, X |
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Optical density |
The property of a medium that describes how fast light travels through it. Light moves slower through a medium with a higher optical density |
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Optical fibre |
A thin flexible tube of glass or plastic that can carry light signals using total internal reflection |
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Ordered/ordinal data |
Categoric data where the categories can be put in order |
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Pair production |
A process of converting energy to mass in which a gamma ray photon has enough energy to produce a particle-antiparticle pair |
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Path difference |
The amount by which the path traveled by one wave is longer that the path traveled by another wave |
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Peer review |
The evaluation of a scientific report by other scientists who are experts in the same area (peers). They go through it bit by bit, examining the methods and data, and checking it's all clear and logical |
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Percentage uncertainty |
The uncertainty given as a percentage of the measurement given |
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Period |
The time taken for one whole wave cycle to pass a given point |
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Phase |
A measurement of the position of a certain point on a wave cycle, measured as an angle (in degrees or radians) or in fractions of a cycle |
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Phase difference |
The amount bu which one wave lags behind another, measured as an angle (in degrees or radians) or in fractions of a cycle |
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Photoelectric effect |
The emission of electrons from a metal when light of a high enough frequency is shone on it |
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Photoelectron |
An electron released through the photoelectric effect |
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Photon |
A discrete wave-packet of EM waves |
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Plastic |
A plastic material is permanently stretched once the forces acting on it are removed |
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Polarised wave |
A wave in which all the vibrations are in one direction or plane |
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Polarising filter |
A filter that only transmits vibrations of a wave in one direction or plane, called the plane of transmission |
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Positron |
The antiparticle of an electron |
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Potential difference (p.d.) |
The work done moving a unit charge between two points in a circuit |
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Potential divider |
A circuit containing a voltage source and a pair of resistors. The voltage across one of the resistors is used as an output voltage. If the resistors aren't fixed, the circuit will be capable of producing a variable output voltage |
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Power |
The rate of transfer of energy or the rate of doing work. It's measured in watts (W), where 1 watt is equivalent to 1 joule per second |
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Precise result |
The smaller the amount of spread of your data from the mean, the more precise it is |
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Prediction |
A specific testable statement about what will happen in an experiment, based on observation, experience or a hypothesis |
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Principle of conservation of energy |
Energy cannot be created or destroyed. Energy can be transferred from one form to another but the total amount of energy in a closed system will not change |
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Progressive wave |
A moving wave that carries energy from one place to another without transferring any material |
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Projectile motion |
Motion with a constant horizontal velocity and a vertical velocity affected by acceleration due to gravity |
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Proton |
A positively charged baryon with a relative mass of 1 |
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Proton number |
The number of protons in an atom of an element |
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Pulse broadening |
When signal in an optical fibre gets wider (broader) as it is transmitted, due to dispersion |
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Quantum number |
A number that represents a property of a particle that must be conserved in all interactions; for example, baryon number and lepton number. Strangeness is an exception to this as it is not conserved in weak interactions |
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Quark |
A fundamental particle that makes up hadrons |
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Random error |
An error introduced by variables which you cannot control |
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Reflection |
When a wave bounces back as it hits a boundary |
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Refraction |
When a wave changes direction and speed as it enters a medium with a different optical density |
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Relative refractive index |
The ratio of the speed of light in one material to the speed of light in a second material |
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Repeatable result |
A result is repeatable if you can repeat an experiment multiple times and get the same result |
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Reproducible result |
A result is reproducible if someone else can recreate your experiment using different equipment or methods, and get the same result as you do |
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Resistance |
A component has a resistance of 1 ohm if a potential difference of 1V across it makes a current of 1A flow through it. Resistance is measured in ohms |
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Resistivity |
The resistance of a 1m length of a material with a 1m2 cross-sectional area. It is measured in ohm-metres |
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Resolution |
The smallest change in whats being measured that can be detected by the equipment |
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Resonant frequency |
A frequency at which a stationary wave is formed because an exact number of waves are produced in the time it takes for a wave to get to the end of the vibrating medium and back again |
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Rest energy |
The amount of energy that would be produced if all of a particle's mass was transformed into energy |
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Resultant vector |
The vector that's formed when two or more vectors are added together |
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Ripple tank |
A shallow tank of water in which water waves are created by a vibrating dipper |
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Scalar |
A quantity with a size but no direction |
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Second harmonic |
The resonant frequency at which the wavelength is the length of the vibrating medium. It is twice the frequency of the first harmonic |
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Signal degredation |
Where an optical signal loses amplitude or is broadened whilst travelling. This can lead to information loss |
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Spark counter |
A device used to detect ionising radiation |
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Specific charge |
The charge per unit mass of a particle |
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Speed |
How fast something is moving, regardless of direction |
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Stationary wave |
A wave created by the superposition of two progressive waves with the same frequency (or wavelength) and amplitude, moving in opposite directions |
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Stiffness constant |
The force needed to extend an object per unit extension. Each object has its own stiffness constant |
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Stopping potential |
The potential difference needed to stop the fastest moving photoelectrons in the photoelectric effect |
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Strain |
The change in length divided by the original length of the material |
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Strangeness |
A property which particle that contain strange quarks have. Strange particles are always produced in pairs |
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Stress |
The force applied divided by the cross-sectional area |
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Strong nuclear force |
A fundamental force with a short range which is attractive at small separations and repulsive at very small separations. Responsible for the stability of nuclei |
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Superconductor |
A material that has zero resistivity when cooled below a critical (transitional) temperature |
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Superposition |
The combination of displacements experience in the instant that two waves pass each other |
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Systematic error
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An error introduced by the experimental apparatus or method |
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Tangent |
A line drawn on a graph that is parallel to the curve at the point that it meets it. Used to calculate the gradient of a curve at a point |
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Tensile force |
A force which stretches something |
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Tensile strain |
The change in length divided by the original length of the material |
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Tensile stress |
The force applied divided by the cross-sectional area |
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Terminal potential difference |
The potential difference between the two terminals of a power supply. This is equal to e.m.f. when there is no internal resistance |
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Terminal speed |
The speed at which the driving force(s) match the frictional force(s) |
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Thermistor |
A resistor with a resistance that depends on it temperature - it is a type of semiconductor |
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Third harmonic |
A resonant frequency at which one and a half wavelengths fit along the vibrating medium. It is three times the frequency of the first harmonic |
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Threshold frequency |
The lowest frequency of light that when shone on a metal will causes electrons to be released from it by the photoelectric effect |
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Total destructive interference |
Destructive interference in which the waves completely cancel each other out |
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Total internal reflection |
When all light is completely reflected back into a medium at a boundary with another medium, instead of being refracted. It only happens at angles of incidence greater than the critical angle |
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Transitional temperature |
The critical temperature at and below which a superconductor has zero resistivity |
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Transverse wave |
A wave in which the displacement of particles/fields (vibrations) is at right angles to the direction of energy propagation |
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Ultimate tensile stress |
The maximum stress that a material can withstand |
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Uncertainty |
An interval in which the true value of a measurement is likely to lie, given with a level of confidence or probability that the true value lies in that interval |
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Valid conclusion |
A conclusion supported by valid data, known as evidence |
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Valid result |
A valid result arises from a suitable procedure to answer the original question |
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Validation |
The process of repeating an experiment done by someone else, and using the theory to make new predictions and then testing them with new experiments, in order to provide evidence for or refute the theory |
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Variable |
A quantity in an experiment or investigation that can change or be changed |
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Vector |
A quantity with a size and a direction |
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Velocity |
The rate of change of displacement |
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Vibration particle |
A piece of equipment which has a moving plate that is able to oscillate rapidly at a set frequency |
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Virtual particle |
A particle that only exists for a short amount of time, e.g. an exchange particle |
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Volt (V) |
The unit of potential difference. The potential difference across a component is 1V when you convert 1J of energy moving 1C of charge through the component |
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Voltmeter |
A component used to measure the potential difference across another component in a circuit |
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Watt (W) |
The unit of power. A watt is defined as a rate of energy transfer equal to 1J per second |
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Wave-particle duality |
All particles have both particle and wave properties. Waves can also show particle properties |
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Wave speed |
The speed that a wave travels at |
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Wavelength |
The length of one whole wave oscillation or wave cycle, e.g. the distance between two crests (or troughs) of a wave |
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Weak interaction |
A fundamental force that has a short range and can change the character of a quark |
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Weight |
The force experience by a mass due to a gravitational field |
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Work |
Work is the amount of energy transferred from one form to another when a force moves an object through a distance |
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Work function |
The minimum amount of energy required for an electron to escape a metal's surface |
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Worst lines |
Lines of best fit which have the maximum and minimum possible slopes for the data and which should go through all the error bars |
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Yield point (or yield stress) |
The stress at which a large amount of plastic deformation takes place with a constant or reduced load |
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Young modulus |
The stress divided by strain for a material, up to its limit of proportionality |
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Zero error |
When a measuring instrument falsely reads a non-zero value when the true value being measured is zero |
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Zero order line |
The line of maximum brightness at the centre of a diffraction grating interference pattern. It's in the same direction as the incident beam |