AQA GCSE Physics key terms

The normal force acting per unit area of a surface.

Repeated changes in pressure that travel through a medium as a sound wave.

The input coil of a transformer, connected to the alternating supply.

The point where rays parallel to the principal axis meet after passing through a convex lens, or appear to come from after passing through a concave lens.

The rule that, for a balanced object, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot.

An estimate of what may happen in the future, based on evidence and assumptions available at the time.

A positively charged particle found in an atomic nucleus.

A forming star made of gas drawn together by gravity, before sustained hydrogen fusion begins in its core.

A longitudinal seismic wave that can travel through solids and liquids.

Energy transferred by waves or particles emitted from a source.

A balance in which radiation is absorbed and emitted at the same rate, so there is no temperature change due to radiation.

A measure of the risk of harm from exposure of the body to radiation.

The unwanted presence of radioactive material on or inside an object or organism, or in the environment.

A process in which an unstable atomic nucleus emits radiation and changes; the moment at which a particular nucleus decays cannot be predicted.

Radioactive material carried through the environment after a nuclear explosion or accident.

A radioactive substance introduced into the body so that its movement or concentration can be detected from outside.

Unwanted radioactive material that must be managed safely because some of it remains dangerous for a long time.

A radioactive isotope attached to a substance chosen to travel to, or collect in, a particular part of the body.

The treatment of unwanted tissue, such as a cancerous tumour, using ionising radiation.

A radioactive gas released naturally from rocks and the ground that can enter buildings.

Motion in which molecules continually move at different speeds and in changing directions.

A process whose outcome for an individual event cannot be predicted with certainty.

A region of a longitudinal wave where the particles of the medium are further apart than usual.

The change in momentum divided by the time taken. This is equal to the resultant force acting on the object.

The decrease in temperature per unit time; it can be used to compare how quickly samples cool.

A line showing the direction in which a wave travels.

The time between a driver noticing a need to stop and applying the brakes.