Keywords

• Acceleration

  The rate at which velocity changes.
• Air Resistance (Drag)


  The force opposing bodies which are travelling through air.
• Alpha Particle

  A helium nucleus produced in radioactive decay
• Alternating Current

  A flow of electric charge that regularly reverses its direction.
• Ammeter


  A device used to measure the current in an electrical circuit.
• Amplified

  Increased in size or power.
• Amp


  The SI unit of current.
• Analogue Electrical Signal


  Electrical signals, usually voltages, that have continuously variable values.
• Angle of Incidence


  The angle between a ray of light arriving at a surface and the normal.
• Angle of Reflection


  The angle between a ray of light reflected from a surface and the normal.
• Balanced

  Equal forces acting on an object in opposite directions.
• Becquerel


  Unit that measures the rate at which a sample of radioactive material decays.
• Beta Particle

  An electron emitted by an unstable nucleus.
• Braking Distance

  The distance a vehicle travels after the brakes have been applied before it stops.
• Brownian Motion

  The random movement of particles in a liquid or gas that is caused by particle and medium collisions.
• Cell Mutation

  A change in the function of a living cell, sometimes caused by ionizing radiation.
• Centre of Gravity

  The point where the entire weight of an object appears to act.
• Chain Reaction

  A series of reactions in which one of the products of the reaction initiates further reactions.
• Circuit Breaker

  A reusable safety switch that breaks the circuit when the current becomes too high.
• Comet


  A ball of frozen dust and rock that orbits the sun and has a tail that glows.
• Conductor (Electrical)

  A material that allows electricity to flow easily through them.
• Contact Force

  A force that is exerted only when two objects are in contact.
• Control Rod

  These are used in nuclear reactors, they absorb some of the neutrons which cause the fission reactions to happen. By lowering them into the reactor, the rate of reaction slows down.
• Controlled Nuclear Fission

  Involves the slow and useful release of energy in a nuclear reactor.
• Critical Angle

  The minimum angle of incidence for which a light ray is totally internally reflected within a medium.
• Current


  Rate of flow of electrical charge.
• Density

  Mass per unit volume of a substance
• Diffraction

  Occurs when an object causes a wave to change direction and bend around it
• Digital Electrical Signal


  A digital signal that has only two possible values, such a 1 and 0.
• Displacement


  Distance moved in a specific direction: a vector quantity.
• Distance

  Distance moved without considering direction: a scalar quantity.
• Drag Force

  The force that opposes the motion of an object through a gas or a liquid.
• Earthed

  Having a very low resistance connection to the general mass of the earth, taken as always being a 0 V.
• Efficiency

  A measure of how effectively energy is transformed into a useful form.
• Elastic


  Able to return to its former shape and size after it has been deformed.
• Elastic Limit

  Maximum stress that a material will withstand without permanent deformation.
• Electric Charge

  The property of particles that causes electrical effects.
• Electromagnetic (EM) Wave


  Waves that require no medium through which to travel, they carry energy through variation in the magnetic and electrical fields in space.
• Electromagnetic Spectrum

  The arrangement of waves of radiant energy in order of wavelength and frequency.
• Electron

  A subatomic particle that has a negative charge.