# Physics Words

• Absorb To soak up or take in
• AC The abbreviation for Alternating Current - current switches between positive and negative values
• Accelerate To get faster - an increase in velocity.
• Acceleration The rate of change of velocity
• Acid rain When rain falls and is acidic rather than neutral.
• Air resistance A force that acts against anything moving through air
• Alpha A type of ionising radiation. The nucleus of a helium atom.
• Alpha particle A type of ionising radiation. The nucleus of a helium atom.
• Alpha radiation A type of ionising radiation. The nucleus of a helium atom.
• Alpha scattering experiment An experiment done in the early 20th Century that provided evidence for atoms being made of electrons orbiting a central, positive nucleus.
• Alternating Current AC stands for this - current switches between positive and negative values
• Aluminium A low density metal (symbol Al)
• Ammeter A device that is used to measure current in Amps
• Amp The unit for current.
• Ampere The unit for current.
• Amplitude The height of a wave
• Angle of incidence The angle between the incident ray and the normal
• Angle of reflection The angle between the reflected ray and the normal
• Angle of refraction The angle between the refracted ray and the normal
• Asteroid A rock that orbits a star
• Atom The smallest particle of an element that can exist
• Background radiation Radiation that is all around you all of the time.
• Balanced forces When the forces acting on an object cancel out - the resultant force is zero.
• Battery A source of electrical power - they give out Direct Current (DC) only
• Becquerel A unit of radioactivity equal to 1 count per second
• Beta particle A type of ionising radiation. A high energy electron from the nucleus
• Beta radiation A type of ionising radiation. The nucleus of a helium atom.
• Big Bang theory A theory about how the universe started.
• Billion One thousand million
• Biofuel A fuel derived from plants
• Biomass The cellular mass of lliving or recently dead organisms.
• Black hole the most concentrated state of matter, from which even light cannot escape
• Boiler A part of a power station where a fuel is burned in order to turn water into steam.
• Bq The abbreviation for Becquerel, a unit of radioactivity
• Braking distance The distance a car travels in the time it takes the car to stop AFTER the driver has put their foot on the brake.
• C The unit for charge - it stands for "coulomb"
• Cable grip The part of a plug that keeps the cable in place.
• Calibrate Check that an instrument is measuring correctly,by comparing against a standard.
• Carbon dioxide A greenhouse gas produced when most fuels burn - it helps cause global warming.
• Carbon dioxide (in Physics) A greenhouse gas produced when most fuels burn - it helps cause global warming.
• Cell (in Physics) A source of electrical energy. Two or more of these put together make up a battery.
• Centre of mass The point of an object that all of its mass can be thought as being centred on.
• Chain reaction This occurs when one nuclear fission reaction produces neutrons that start the next fission reaction.
• Charge An electrical property of a particle - can be positive or negative. It is measured in Coulombs (C).
• Circuit breaker A device that switches off a circuit if there is too much current.
• Circuit diagram A diagram that shows how to set up an electrical circuit.
• Circuit symbols A diagram that shows you which electric device to use.
• CMBR Cosmic Microwave Background Radiation - One of the main sources of evidence for the Big Bang Theory.
• Coal-fired power station A power station that burns coal in order to generate electricity.
• Component (electrical) A device used in an electric circuit, e.g. a bulb or a cell.
• Concave lens Also called a "diverging lens", a lens that spreads rays of light outwards.
• Conduction (electrical) The flow of electricity through a conductor.
• Conduction (thermal) The flow of heat energy through a solid. The energy moves from hot areas to cold areas in the solid.
• Conductivity How well a material conducts heat or electricity.
• Conductor A substance that allows electricity or thermal (heat energy) to pass through it easily.
• Conservation (of energy) When energy is conserved during a process.
• Conservation (of momentum) Momentum is conserved in any collision or explosion, as long as there are no external forces.
• Conservation of energy When energy is conserved during a process.
• Conservation of momentum Momentum is conserved in any collision or explosion, as long as there are no external forces.
• Contact force A force between two objects that arises when they are in contact with each other.
• Control rods Rods that are used in a nuclear power station to control how much energy is generated.
• Convection When heat rises through a liquid or a gas due to a change in density.
• Convection current (in Physics) This current is formed when heat rises through a liquid or a gas due to a change in density.
• Converging lens A lens that converges (brings together) rays of light.
• Convex lens A lens that converges (brings together) rays of light.
• Cooling tower A part of a power station where steam is cooled back into liquid water.
• Copper The best (common) conductor of electricity.
• Cosmic microwave background radiation One of the main sources of evidence for the Big Bang Theory.
• Cost effective When something is able to pay for itself, e.g. a cheap but effective form of house insulation.
• Coulomb The unit for charge - symbol C.
• Count rate The amount of radioactivity being detected every second (measured in Bq).
• Critical angle If light hits a boundary at an angle greater than the critical angle it will undergo total internal reflection.
• Current The rate of flow of charge
• DC The abbreviation for Direct Current - current flows in the same direction.
• Decay (radioactive) When the nucleus of an unstable atom emits either alpha, beta or gamma radiation.
• Decelerate When an object slows down.
• Delocalised electrons Electrons that are free to move around and carry current or heat
• Density Mass divided by volume
• Diffraction When a wave spreads out around a corner or obstacle.
• Diffuse reflection A type of reflection where waves are reflected in many different directions.
• Diode An electrical component that only lets current flow in one direction.
• Direct Current DC stands for this - current flows in the same direction.
• Displacement An element which is more reactive can displace a less reactive element.
• Dissipate To "spread out". For example, when energy spreads out into the surroundings it can be described as "dissipating".
• Distance How far you have gone.
• Distance-time graph A graph that shows an object's distance against time.
• Diverging lens Also called a "concave lens", a lens that spreads rays of light outwards.
• Doppler Effect An apparent change in wavelength of a wave emitted by an object that is moving.
• Double glazing A form of insulation
• Drag A force that acts against anything moving through a gas or a liquid
• Driving force A force that propels an object like a car forwards
• Earth wire One of the three wires in a plug - coloured green and yellow
• Efficiency How much useful energy you get from a device compared to the energy that went into it
• Efficient A device that doesn't waste much energy
• Elastic deformation When a spring is stretched and returns to its original shape.
• Elastic potential energy The energy stored in a stretched elastic band or spring
• Electric current The rate of flow of charge
• Electromagnetic radiation Radiation that travels in waves - for example, light, radio waves and X rays
• Electromagnetic spectrum This is the different forms of electromagnetic radiation arranged in order of wavelength.