AQA A level Physics Questions and Answers

AQA A level Physics Questions and Answers Acceleration The rate of change of velocity Accurate result A result that is close to the true answer Apha decay A type of decay in which an unstable nucleus of an atom emits an alpha particle Alternating current A current that changes with time in a regular cycle Ammeter A component used to measure the current flowing through a circuit Amplitude The maximum displacement of a wave Angle of incidence The angle that incoming light makes to the normal or a boundry Angle of refraction The angle that incoming light makes to the normal of a boundary Annihilation The process by which a particle and its antiparticle meet and their mass gets converted to energy in the form of a pair of gamma ray photons Anomalous result A result that doesn't fit in with the pattern of the other results in a set of data Antimatter The name given to all antiparticles Antineutrino The antiparticle of a neutrino Antiparticle A particle with the same rest mass and energy as its corresponding particle but equal and opposite charge Atom A particle made up of protons and neutrons in a central nucleus and electrons orbiting the nucleus Atomic number The number of protons in an atom of an element Baryon A type of hardon made up of three quarks Baryon number The number of baryons in a particle 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 Breaking stress The lowest stress that is big enough to break a material Brittle A brittle material doesn't deform plastically but snaps when the stress on it reaches a certain point ` Brittle fracture When a stress app;lied to a brittle material causes tiny cracks at the materials surface to get bigger until the material breaks completely Categoric data Data that can be sorted into categories Center of mass The point which you can consider all of an object's weight to act through Circuit symbol A pictorial representation of an electrical component Coherent Sources that have the same wavelength and frequency and a fixed phase difference between them are coherent Compressive force A force which squashes something Constructive interface When two waves interfere to make a wave with a larger displacement Coulomb A unit of charge. One coulomb is the amount of charge that passes in one second when the current is one ampere Couple A pair of forces of equal size which act parallel to each other but in opposite directions Critical angle The angle of incidence at which the angle of refraction in 90 degrees Current The rate of flow of charge in a circuit, measures in amperes Continuous data Data that can have any value on a scale Density The mass per unit volume of a material or object Dependent variable The cariable that you measure in an experiment Destructive interference When two waves interfere to make a wave with a reduced displacement Diffraction When waves spread out as they pass through a narrow gap or go round obstacles 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 Diode A component designed to allow current flow in one direction only. Directly proportional A change in ove variable results in a change in the other variable, the changes are always related by the same constant Discrete data Data that can only take certain values Displacement How far an object has traveled from its starting point in a given direction in the case of a wave, it is the distance a point on a wave has moved from its undisturbed position Drag Friction caused by a fluid (gas or liquid) Efficiency The ratio of useful energy given out by a machine to the amount of energy put into the machine Elastic An elastic material returns to its original shape/length once the forces acting on it are removed Elastic limit The force beyond which a material will be permanently stretched Elastic strain energy The energy stored in a stretched material Electromagnetic force A fundamental force that causes interactions between charged particles. Virtual photons are the exchange particle Electromagnetic spectrum A continuous spectrum of all the possible frequencies of electromagnetic radiation Electromotive force (E.M.F) The amount of electrical energy a power supply transfers to each coulomb of charge Electron A lepton with a relative charge of -1 and a relative mass of 0.0005. Electron capture The process of a proton rich nucleus capturing an electron to turn a proton into a neutron, emitting a neutrino Electron proton collision The process of an electron colliding with a proton and producing a neutron and a neutrino Electron volt The kinetic energy carried by an electron after it has been accelerated through a potential difference of one volt Equilibrium An object is in equilibrium if all the forces acting on it cancel each other out Exchange particle A virtual particle which allows forces to act in a particle interaction Excitation The movement of an electron to a higher energy level in an atom Fernman diagram A diagram used to represent particle ineraction First order line The first line either side of the zero order line in a diffraction grating interference pattern First overtone A resonant frequency of a stationary wave for which the wavelength is the length of the string Free fall The potion of an object undergoing an acceleration of g Frequency The number of whole wave cycles (oscillations) per seconds passing a given point, Or the number of whole wave cycles given out from a source per second. 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 object is moving througha fluid. Fundamental frequency A resonant frequency of a stationsry wave for which the wavelength is double the length of the string Fundamental particle A particle which cannot be split up into smaller particles Gravitational force A fundamental force which causes attraction between objects with a force proportional to their mass Gravitational potential energy The energy an object gains when lifted up Ground state The lowest energy level of an atom Hadron A particle that is affected by the strong nuclear force Hooke's law The extension of a stretched object is proportional to the load or force applied to it, up to the limit of proportionality. Hooke's law limit The point beyond which force is no longer proportional to extension. Also known as the limit of proportionality Hypothesis A specific testable statement based on a theory about what will happen in a test situation Independent variable The variable that you change in an experiment Interference The superposition of two or more waves Internal resistance The resistance created in a power source when the electrons collide with atoms inside the power source Ionisation The process where an electron is removed from to an atom Ionisation energy The energy required to remove an electron from an atom Isotope An isotope of an element has the same proton number as the element but a different nucleon number I-V characteristic A graph which shows how to current flowing through a component changes as the potential difference across it is increased Kinetic energy the energy possessed by a moving object Lepton A fundamental particle that is not affected by the strong nuclear force Lepton number The number of leptons in a particle, the lepton number is counted separately for different types of leptons Level A structure with a rigid object and a pivot in which an effort force works against a load force Light-dependent resistor A resistor with a resistance that depends on the intensity of light falling on it. The resistance decreases with increasing light intensity Limit of proportionality The point beyond which force is no longer proportional to extension. Line spectrum The pattern of lines produced by photons being emitted or absorbed by electrons moving between energy levels in an atom Line absorbtion spectrum A light spectrum with dark lines corresponding to different wavelengths of light that have been absorbed 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 Longitudinal wave A wave in which the vibrations are in the direction of travel of the wave Lost volts The energy wasted per coulomb overcoming the internal resistance of a power source Mass The amount of matter in an object Mass number The number of nucleons in an atom of an element Matter The name given to all particles Maximum The points in an interferance pattern where the intensity is brightest Meson A type of hadron made up of a quark and an antiquark Minimum The points in an interference pattern where the intensity is lowest Model A simplified picture of representation of a real physical situation Moment The turning effect of a force around a turning point Monochromatic A light source that is all of the same wavelength Nucleon A particle in the nucleus of an atom Nucleon number The number of nucleons in an atom of an element Nucleus The centre of an atom containing protons and neutrons Neutrino A lepton with almost zero mass and zero charge Neutron A neutral baryon with a relative mass of one Newton's first law of motion The velocity of an object will not change unless a resultant force acts on it Newton's second law of motion The acceleration of an object is proportional to the resultant force acting on it Newton's third law of motion If an object A exerts a force on object B them object B exerts an equal but opposite force on object A Ohm's law Provided the temperature is constant the current through an ohmic conductor is directly proportional to the potential difference across it Ohmic conductor A component that has a fixed resistance for a particular temperature Optical density The propery of a medium that describes how fast light travels through it. Light moves slower through a medium with a higher optical density Optical fibre A thin flexible tube of glass of plastic that can carry light signals using total internal reflection