A-Level Year 1 & As Textbook Physics Key Words

The ratio between the speed of light in a vacuum and the speed of light in a material

The uncertainty of a measurement given as a fixed quantity

Where some of the energy of a fire-optic signal is absorbed by the material of the optical fibre

The rate of change of velocity

An accurate result is really close to the true answer

A type of decay in which an unstable nucleus of an atom emits an alpha particle

A particle made up of two protons and two neutrons (a helium nucleus)

A component used to measure the current flowing through a circuit

The maximum displacement of a wave, i.e. the distance from the undisturbed position to a crest or trough

The angle that incoming light makes with the normal of a boundary

The angle that refracted light makes with the normal of a boundary

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

A result that doesn't fit in with the pattern of the other results in a set of data

The name given to all antiparticles

The antiparticle of a neutrino

The antiparticle of a neutron

A point of maximum amplitude on a stationary wave

A particle with the same rest mass and energy as its corresponding particle, but equal and opposite charge

The antiparticle of a proton

A particle made up of protons and neutrons in a central nucleus, and electrons orbiting the nucleus

The number of protons in an atom of an element

The change in displacement of an object divivded by the time taken

A type of hadron made up of three quarks. For example, protons and neutrons

The number of baryons in a particle

A type of decay in which an unstable nucleus of an atom emits a beta-minus particle (an electron) and an antineutrino

A type of decay in which an unstable nucleus of an atom emits a beta-plus particle (a positron) and a neutrino

The lowest stress that's big enough to break a material

A brittle material doesn't reform plastically, but snaps when the stress on it reaches a certain point

When a stress applied to a brittle material causes tiny cracks at the material's surface to get bigger until the material breaks completely

Marking a scale on a measuring instrument or checking a scale by measuring a known value

Data that can be sorted into categories

The point which you can consider all of an object's weight to act through

A pictorial representation of an electrical component

A chamber filled with a vapour which is used to track the motion of charged particles

Sources (or waves) that have the same wavelength and frequency and a fixed phase difference between them are coherent

A force which squashes something

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

When two waves interfere to make a wave with a larger displacement

Data that can have any value of a scale

A variable that is kept constant in an experiment

Lots of high-energy particles that are produced from cosmic rays interacting with molecules in the atmosphere

Raditation in the form of charged particles that come from space and hit Earth

A unit of charge. One coulomb is the amount of charge that passes in 1 second when the current is 1 ampere

A pair of forces of equal size which act parallel to each other but in opposite directions

The angle of incidence at which the angle of refraction is 90degrees

Part of a car or other vehicle designed to deform plastically in a crash so less energy is transferred to the people inside

The rate of flow of charge in a circuit. Measured in amperes (A)

The mass per unit volume of a material or object

The variable that you measure in an experiment

When two waves interfere to make a wave with a reduced displacement

When waves spread out as they pass through a narrow gap or go around obstacles

A slide or other thin object that contains lots of equally spaced slits, very close together, used to show diffraction patterns of waves

A component designed to allow current to flow in one direction only

Data that can only take certain values

A form of signal degradation that causes pulse broadening of a fibre-optic signal as it travels

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

Friction caused by a fluid (gas or liquid)

The ratio of useful energy given out by a machine to the amount of energy put into the machine

An elastic material returns to its original shape/length once the forces acting on it are removed

The force (or stress) beyond which a material will be permanently stretched

The energy stored in a stretched material

A fundamental force that causes interactions between charged particles. Vitual photons are the exchange particle

A continuous spectrum of all the possible frequencies of electromagnetic radiation

The amount of electrical energy a power supply transfers to each coulomb of charge

A lepton with a relative charge of -1 and a relative mass of 0.0005. Sometimes called a beta-minus particle

The process of a proton-rich nucleus capturing an electron to turn a proton into a neutron, emitting a neutrino

The process of an electron colliding with a proton and producing a neutron and a neutrino

The kinetic energy carried by an electron after it has been accelerated from rest through a potential difference of one volt

An object is in equilibrium if all the forces acting on it cancel each other out

Valid data arising from an experiment, which can be used to support a conclusion

A virtual particle which allows forces to act in a particle interaction. They are also known as guage bosons

The movement of an electron to a high energy level in an atom

An experiment in which all variables are kept constant apart from the independent and dependent variables

The lowest frequency at which a stationary wave is formed where the wavelength is double the length of the vibrating column

The uncertainty given as a fraction of the measurement taken

The motion of an object undergoing an acceleration of g

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

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

A particle which cannot be split up into smaller particles

A virtual particle which allows forces to act in a particle interaction. They are also known as exchange particles

A device to measure the amount of ionising radiation

A fundamental force which causes attraction between objects with a force proportional to their mass

The energy an object gains when lifted up in a gravitational field, due to its position

The lowest energy level of an atom or the lowest energy level for an electron in an atom

A particle made up of quarks that is affected by the strong nuclear force

The extension of a stretched force is no longer proportional to extension. Also known as the limit of proportionality

A suggested explanation for a fact or observation

A graph which shows how the current flowing through a component changes as the potential difference across it is increased

The impulse acting on an object is equal to the change in momentum of the object

he variable that you change in an experiment

The velocity of an objects at a particular moment in time

The power per unit area

The superposition of two or more waves

The resistance created in a power source when electrons collide with atoms inside the power source and lose energy

The process where an electron is removed from (or added to) an atom

The energy required to remove an electron from an atom in its ground state

One of two or more of an element with the same proton number but a different nucleon number

The relative amounts of isotopes in a substance

The energy possessed by a moving object due to it movement

A fundamental particle that is not affected by the strong nuclear force

The number of leptons in a particle. Lepton number is counted separately for different types of leptons

A structure made of a rigid object rotating around a pivot, in which an effort force works against a load force

An upwards force on an object moving through a fluid

A resistor with a resistance that depends on the intensity of light falling on it. The resistance decreases with increasing light intensity

The point beyond which force is no longer proportional to extension. Also known as Hooke's Law limit

A light spectrum with dark lines corresponding to different wavelengths of light that have been absorbed

A spectrum of bright lines on a dark background corresponding to different wavelengths of light that have been emitted from a light source

A pattern of lines produced by photons being emitted or absorbed by electrons moving between energy levels in an atom

A wave in which the displacement of particles/fields (vibrations) is in the direction of energy propagation

The energy wasted per coulomb overcoming the internal resistance of a power source

The amount of matter in an object

The number of nucleons in an atom of an element

Dispersion caused by different wavelengths of light travelling at different speeds through the material of an optical fibre

The name given to all particles

A point in an interference pattern where the intensity is locally brightest (a location of constructive interference)

A type of hadron made up of a quark and an antiquark. For example, pions and kaons

Dispersion caused by reflected light taking paths of different lengths in an optical fibre

The turning effect of a force around a turning point

The moment caused by two equal forces acting parallel to each other but in opposite directions around a turning point

The momentum of an object is the product of its mass and velocity

A light source that is all of the same wavelength (or frequency)

A lepton with (almost) zero mass and zero charge

A neutral baryon with a relative mass of 1

The velocity of an object will not change unless a resultant force acts on it

The acceleration of an object is proportional to the resultant velocity acting on it

If an object A exerts a force on object B, then object B exerts anequal and opposite force on object A

A point of minimum amplitude on a stationary wave

The process of an unstable nucleus emitting particles in order to become more stable

A particle in the nucleus of an atom (which can be a proton or a neutron)

The number of nucleons in an atom of an element

The centre of an atom, containing protons and neutrons

A notation that tells you the nucleon number, A and proton number, Z, of an element, X

The property of a medium that describes how fast light travels through it. Light moves slower through a medium with a higher optical density

A thin flexible tube of glass or plastic that can carry light signals using total internal reflection

Categoric data where the categories can be put in order

A process of converting energy to mass in which a gamma ray photon has enough energy to produce a particle-antiparticle pair

The amount by which the path traveled by one wave is longer that the path traveled by another wave

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

The uncertainty given as a percentage of the measurement given

The time taken for one whole wave cycle to pass a given point

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

The amount bu which one wave lags behind another, measured as an angle (in degrees or radians) or in fractions of a cycle

The emission of electrons from a metal when light of a high enough frequency is shone on it

An electron released through the photoelectric effect

A discrete wave-packet of EM waves

A plastic material is permanently stretched once the forces acting on it are removed

A wave in which all the vibrations are in one direction or plane

A filter that only transmits vibrations of a wave in one direction or plane, called the plane of transmission

The antiparticle of an electron

The work done moving a unit charge between two points in a circuit

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

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

The smaller the amount of spread of your data from the mean, the more precise it is

A specific testable statement about what will happen in an experiment, based on observation, experience or a hypothesis

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

A moving wave that carries energy from one place to another without transferring any material

Motion with a constant horizontal velocity and a vertical velocity affected by acceleration due to gravity

A positively charged baryon with a relative mass of 1

The number of protons in an atom of an element

When signal in an optical fibre gets wider (broader) as it is transmitted, due to dispersion

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

A fundamental particle that makes up hadrons

An error introduced by variables which you cannot control

When a wave bounces back as it hits a boundary

When a wave changes direction and speed as it enters a medium with a different optical density

The ratio of the speed of light in one material to the speed of light in a second material

A result is repeatable if you can repeat an experiment multiple times and get the same 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

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

The resistance of a 1m length of a material with a 1m2 cross-sectional area. It is measured in ohm-metres

The smallest change in whats being measured that can be detected by the equipment

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

The amount of energy that would be produced if all of a particle's mass was transformed into energy

The vector that's formed when two or more vectors are added together

A shallow tank of water in which water waves are created by a vibrating dipper

A quantity with a size but no direction

The resonant frequency at which the wavelength is the length of the vibrating medium. It is twice the frequency of the first harmonic

Where an optical signal loses amplitude or is broadened whilst travelling. This can lead to information loss

A device used to detect ionising radiation

The charge per unit mass of a particle

How fast something is moving, regardless of direction

A wave created by the superposition of two progressive waves with the same frequency (or wavelength) and amplitude, moving in opposite directions

The force needed to extend an object per unit extension. Each object has its own stiffness constant

The potential difference needed to stop the fastest moving photoelectrons in the photoelectric effect

The change in length divided by the original length of the material

A property which particle that contain strange quarks have. Strange particles are always produced in pairs

The force applied divided by the cross-sectional area

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

A material that has zero resistivity when cooled below a critical (transitional) temperature

The combination of displacements experience in the instant that two waves pass each other

An error introduced by the experimental apparatus or method

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

A force which stretches something

The change in length divided by the original length of the material

The force applied divided by the cross-sectional area

The potential difference between the two terminals of a power supply. This is equal to e.m.f. when there is no internal resistance

The speed at which the driving force(s) match the frictional force(s)

A resistor with a resistance that depends on it temperature - it is a type of semiconductor

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

The lowest frequency of light that when shone on a metal will causes electrons to be released from it by the photoelectric effect

Destructive interference in which the waves completely cancel each other out

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

The critical temperature at and below which a superconductor has zero resistivity

A wave in which the displacement of particles/fields (vibrations) is at right angles to the direction of energy propagation

The maximum stress that a material can withstand

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

A conclusion supported by valid data, known as evidence

A valid result arises from a suitable procedure to answer the original question

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

A quantity in an experiment or investigation that can change or be changed

A quantity with a size and a direction

The rate of change of displacement

A piece of equipment which has a moving plate that is able to oscillate rapidly at a set frequency

A particle that only exists for a short amount of time, e.g. an exchange particle

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

A component used to measure the potential difference across another component in a circuit

The unit of power. A watt is defined as a rate of energy transfer equal to 1J per second

All particles have both particle and wave properties. Waves can also show particle properties

The speed that a wave travels at

The length of one whole wave oscillation or wave cycle, e.g. the distance between two crests (or troughs) of a wave

A fundamental force that has a short range and can change the character of a quark

The force experience by a mass due to a gravitational field

Work is the amount of energy transferred from one form to another when a force moves an object through a distance

The minimum amount of energy required for an electron to escape a metal's surface

Lines of best fit which have the maximum and minimum possible slopes for the data and which should go through all the error bars

The stress at which a large amount of plastic deformation takes place with a constant or reduced load

The stress divided by strain for a material, up to its limit of proportionality

When a measuring instrument falsely reads a non-zero value when the true value being measured is zero

The line of maximum brightness at the centre of a diffraction grating interference pattern. It's in the same direction as the incident beam