- 1 -Glossary of terms used in A-LevelPhysicsAbsoluteAbsolute zerozero ofof temperaturetemperature：the lower fixed point on the thermodynamic scale of temperature; it is considered to be the lowest possible temperatme in the universe. AbsoluteAbsolute scalescale ofof temperaturetemperature：a theoretical temperature scale that does not depend on the thermometric property of a material. AccelerationAcceleration： the rate of change of velocity with respect to time. It has the SI units of ms,2AccelerationAcceleration ofof freefree fallfall：the rate of change of velocity of an object when it falls freely towards the Earths surface under the sole influence of me gravitational pull of me Earth. It is denoted by the symbol g and has a numerical value of 9.81 ms.2AccuracyAccuracy：the proximity of the observed reading on an instrument to the true or actual value of the physical quantity being measured. AmmeterAmmeter：an electrical instrument that measures the electric current in a circuit. Amount of substance： the number of moles of a substance (see moles).AmpereAmpere： the constant current that exerts a force of 2N per metre 710length on two straight, parallel and infinitely long wire of negligible cross-sectional area when that current flows through the two wires. It is the SI unit of an electric current and is represented by the symbol A. AmplitudeAmplitude： the maximum displacement from the equilibrium position to the crest or trough of a sinusoidal wave. AngularAngular displacementdisplacement： the angle through which a rotating axis turns. It is usually measured in radians. AngularAngular velocityvelocity： the rate of change of angular displacement with respect to time, It is measured in rad s.1AnodeAnode：positive electrode. AntinodesAntinodes：points of maximum displacement in a stationary wave.AtmosphereAtmosphere： a unit of pressure equal to 1.01 Pa or 760mmHg.510AtmosphericAtmospheric pressurepressure： the pressure at a point due to the weight of the air column above it. AtomAtom： the smallest part of an element that can exist naturally. AttoAtto： a prefix used in the metric system of units to denote a sub-multiple of .1810- 2 -AvogadroAvogadro constantconstant: the number of atoms in exactly 0.012 kg of carbon-12 and has a numerical value of 6.02 mol. It is denoted by or .23101 ANLBarometerBarometer: a device that measures atmospheric pressure-Base quantity; one of the seven arbitrarily chosen physical quantities that is used to define other physical quantities in the SI system. BaseBase unitunit: a unit of base quantity that is used to define the SI units of other physical quantities. BoilingBoiling: the process in which a liquid changes into vapour at a definite temperature. BoilingBoiling pointpoint: the temperature of a liquid as it changes into the gaseous state when the saturated vapour pressure of the liquid equals to the external pressure acting on it. BoltzmannBoltzmann constantconstant: the ratio of the molar gas constant R to the Avogadro constant .ANBoylesBoyles lawlaw: the pressure () of a given mass of gas at constant ptemperature is inversely proportional to its volume ().VBrownianBrownian motionmotion; the continuous and random movement of tiny microscopic particles suspended in a fluid. CathodeCathode RayRay OscilloscopeOscilloscope (CRO)(CRO): an electronic instrument that uses the cathode ray tube to convert electrical signals into a displacement-time graph on the CROs screen from which essential information such as amplitude and the period of a signal could be measured. CathodeCathode: negative electrode. CelsiusCelsius scalescale ofof temperaturetemperature: a scale of temperature that is adjusted to agree with the thermodynamic scale of temperature.CentiCenti: a prefix used in the metric system to denote sub-multiple of .210CentigradeCentigrade scalescale ofof temperaturetemperature: an empirical scale of temperature in which the lower and upper fixed points are the freezing and boiling point of water respectively. CentreCentre ofof gravitygravity: the single point in a body through which the entire weight of that body appears to act. CentreCentre ofof massmass: the single point in a body through which the entire mass of that body appears to act. CentripetalCentripetal accelerationacceleration: the acceleration of a moving object that is always directed towards the centre of the circular path on which the object is travelling. CentripetalCentripetal forceforce: the force on a moving object that is always directed towards the centre of the circular path on which the object is travelling. CharlesCharles lawlaw: the volume (V) of a fixed mass of gas at constant pressure - 3 -is directly proportional to its thermodynamic temperature (T).- 4 -CompressionCompression: a region of higher pressure in a medium. CompressiveCompressive forcesforces: two equal but oppositely directed forces acting on an object that r