C

calibrate - make a scale for an instrument by measuring known quantities
calorimeter - container used in heat experiments, often in specific heat measurement
calorie - unit of heat and energy no longer used. 1 Calorie = 4.1868 J
Callisto - one of the four Galilean satellites of Jupiter (discovered in 1610)
candela - unit of luminous intensity
candle power - original name for luminous intensity
Canopus - bright star in constellation Carina. Luminosity = 200 000 Suns!
capacitor - a component that can store electric charge, releasing it at a known rate
capillary action - rise of liquid up a narrow tube due to the surface tension of the liquid
carbon cycle - most important energy cycle in massive stars
carbon dating - the use of the isotope carbon 14 to date archaeological specimens
Carnot cycle - a specific reversible cycle in thermodynamics
cartesian diver - hollow toy diver with a hole in its body. Pressure changes make it rise or sink
cassegrain telescope - a reflecting telescope with convex secondary mirror
cathode - negative electrode
cathode ray - a stream of electrons from the cathode of a vacuum tube
caustic curve - locus of the intersection of light rays after reflection by a spherical surface
CCD - charge coupled device, used in CCD cameras
celestial equator - projection of the Earth's equator on the star sphere
celestial pole - the projection of the Earth's axis on the celestial sphere
celestial sphere - imaginary sphere of infinite radius centred on the Earth's centre
cell - in Physics the correct name for a simple battery with only one pair of electrodes
celsius scale - scale of temperature, scientific named for the centigrade scale
centre of curvature – of a mirror or lens surface, centre by which the surface is constructed
centre of mass - point on which a body will balance. Point about which there is no resultant moment
centripetal - directed towards the centre of a circle, as in centripetal force.
centrifugal - directed away from the centre of a circle (reaction to centripetal)
cepheid - short period, regular variable star.
cerenkov - radiation produced by charged particles moving faster than light in a liquid
Ceres - the largest asteroid, first one to be discovered - 1801
CERN - European laboratory for particle Physics in Geneva.
chain reaction - as in nuclear fission, one nucleus splits releasing neutrons that split more atoms
Chandrasekhar limit - the maximum possible mass of a white dwarf, 1.4 times the Sun's mass
chaos - behaviour that cannot be predicted
chaos theory - one action may affect another and it can be impossible to predict the final outcome
Charles' Law - for a gas, V/T is constant if the pressure remains constant
charm - a quantum number used in hadron and quark theory
Charon - one component of the Pluto 'double planet system'
choke - an inductor of high impedance used in a.c. circuits to reduce the signal
chromatic aberration - defects of lenses due to differing refraction of different colours
chromatic scale - a scale going up in semitones, thirteen notes to the octave
chromosphere - the Sun's atmosphere of ionised gases; extends to 2500 km with a temperature 28 000 ^oC
circuit breaker - device to cut off an electrical supply (modern replacement for a fuse)
circumpolar - stars that never set
classical physics - Physics before the Quantum Theory and Relativity
cleavage - the ability to separate a crystal into two parts along a plane
clockwise - turning in the same direction as the motion of the hands of a clock
cloud chamber - a piece of apparatus used to investigate the tracks of charged particles
coaxial cable - a cable made of to or more coaxial conductors insulated from each other
coherent - no abrupt phases changes, as in coherent light from a laser
cohesion - attraction between similar substances
collector - one of the three regions of a transistor
collimator - device for producing a parallel beam of light
coma - defect of a mirror or lens giving a comet-shaped image of an off axis object
comet - large lump of rock and ice orbiting the Sun
commutator - device in an electric motor that changes the direction of the current in the coil
CD - compact disc, laser read disc storage of information
comparator - an instrument for comparing two photographic plates
component - effectiveness of a vector in a particular direction, as in 'component of a force'
compound pendulum - pendulum where the mass is spread along the length of the pendulum
compression - squashing force or the amount something has been squashed
Compton effect - interaction between a photon and an electron giving a transfer of energy
concave - curved inwards
concave lens - a lens that spreads out (diverges) a beam of light
concave mirror - a mirror that focuses a beam of light
condense - turn from a vapour to a liquid
condenser - a piece of apparatus for removing heat by a continuous stream of water
conduction - method of transfer of heat energy or electrical energy by particle vibration
conduction band - partly filled upper energy band in a solid in which the electrons are free to move
conductivity - inverse of resistivity
conductor - material that will transfer heat energy or electrical energy by particle vibration
cones - nerve endings in the retina, insensitive to dim light but detect fine detail and colour
conjunction - when two planets are visible close together in the sky
consequence - the result of something happening when an event occurs
conserved - to stay the same value in a reaction, experiment or interaction
conservation - keeping something the same before and after an event, staying unchanged
constant - unchanging, a quantity that does not vary, 'a constant' or 'to stay constant'
constantan - alloy of about 50% copper and 50% nickel. Quite high resistance.
constellation - a group of stars visible from the Earth – e.g. Plough, Orion, Leo
continental drift - movement of tectonic plates 'carrying' the continents across the Earth's surface
control - in an experiment a comparison quantity that is not changed by the experimenter
control rods - rods of metal (usually boron or boron steel) used to regulate a nuclear reactor
convection - method of transfer of heat energy by movement of the fluid
conventional - usual or agreed, as in 'conventional current direction'
converging - bringing together as with a beam of light in 'diverging lens', 'diverging mirror'
convex - curved outwards
convex lens - a lens that focuses a beam of light
convex mirror - a mirror that spreads out (diverges) a beam of light
coolant - a fluid used to keep apparatus at a steady temperature (water cooled car engine)
coordinates - numbers used to describe the position of an object relative to fixed axes
Copernicus - a very conspicuous large lunar crater
core - term used to describe the central part of a solenoid, transformer or nuclear reactor
coriolis force - a fictitious force proposed to explain the motion of projectiles a rotating Earth
corkscrew rule - a way of finding the direction of the lines of force in a magnetic field
corpuscle - small particle
corpuscular theory - theory (held by Newton) that light was made of small particles
cosmology - the Physics of the origin, development and structure of the Universe
coulomb - unit of electric charge
Coulomb's Law - the law of force between two electric charges
couple - turning effect of a pair of forces
CPU - central processing unit
Crab nebula - relic of a supernova explosion in the constellation Taurus (M1)
crater - formed on the Moon by meteorite bombardment
create - make
crest - the 'top' of a wave
critical angle - angle of incidence in glass (for example) where the angle of refraction in air is 90^o
critical mass - the minimum mass needed to sustain a nuclear fission reaction
critical temperature - temperature above which a gas can't be liquefied by pressure alone
Crookes' radiometer - a piece of apparatus for detecting heat radiation
crushing can - simple piece of apparatus used to show air pressure by crushing a thin metal can
cryogenics - the study of materials at low temperatures
crystal lattice - solid with a structure of a regular arrangement of atoms
crystallography - the branch of science dealing with the study of crystals
Curie - unit of radioactive decay. 3.7x10¹⁰ Becquerel
curvature of a wave or surface - 1/(radius of curvature of that wave or surface)
cusp - one of the two 'horns' of the crescent Moon or a planet
cyclotron - one form of apparatus for accelerating charged particles
Cygnus X1 - intense source of X rays in the constellation Cygnus discovered in 1966