Physics key terms

A relationship in which one quantity increases by the same factor as another; its graph is a straight line through the origin.

A potential difference whose polarity remains in one direction, even if its magnitude changes.

A voltage that keeps the same polarity, so one terminal remains positive relative to the other.

The separation of white light into colours because different wavelengths travel at different speeds and refract by different amounts in a material.

Fluid pushed out of the space occupied by the immersed part of an object.

The volume of fluid that is moved aside by the immersed part of an object.

The change in position from a starting point to an ending point, including direction; it is a vector quantity.

Energy that has spread into the thermal stores of the surroundings and is less available for a useful purpose.

The spreading of energy into less useful stores, usually the thermal energy stores of objects and their surroundings.

The total length of the route an object travels, regardless of direction.

The distance moved in the direction in which a force acts.

The distance an object moves along the direction in which the force acts, measured in metres (m).

A lever arrangement that makes the load move farther or faster than the effort point; this requires a larger effort force.

A graph showing how an object's total distance travelled changes with time.

The total length of the path an object has travelled, regardless of direction.

The liquid collected after vapour has condensed during distillation.

A change in an object's shape caused by a force, such as stretching, compression or bending.

Something that diverts a driver's attention from driving and can delay their response to a hazard.

A lens that refracts initially parallel rays so that they spread out and appear to have come from a principal focus on the incident side.

The electricity supply delivered to buildings through the National Grid and accessed through mains sockets.

The electricity supplied to homes through the UK electricity network.

A change in the observed frequency and wavelength of waves caused by motion of the wave source relative to an observer.

A device worn by a worker to monitor the radiation dose that they receive.

A resistive force exerted by a fluid, such as air or water, which acts against an object's motion through the fluid.

A body that orbits the Sun and is classed separately from the eight planets; Pluto is an example.

A microphone in which sound moves a coil through a magnetic field, inducing an electrical signal.

A generator that produces direct current, usually by using a split-ring commutator.

The eardrum is a thin membrane in the ear that vibrates when sound waves reach it.