Edexcel GCSE Physics key terms

The smaller daughter nuclei formed when a heavy nucleus splits.

A sample of gas in which no gas enters or leaves, so the number of gas particles remains unchanged.

A circuit component whose resistance is designed to remain constant under fixed physical conditions.

A substance that can flow and change shape to fit its container; liquids and gases are fluids.

The emission of visible light by a substance after it has absorbed radiation such as ultraviolet.

The distance from the centre of a lens to its principal focus, represented by $f$.

A push or pull that can change an object's velocity; its unit is the newton, N.

A condition in which the vector sum of the forces is zero, so there is no resultant force and no acceleration.

A pulling interaction that tends to keep particles close together.

Coal, oil or natural gas: a non-renewable fuel containing a chemical energy store that can be released by burning.

A simplified diagram that represents one object as a dot or box and shows every external force acting on it as a labelled arrow.

Motion in which gravity is the only force acting on an object.

The physical change from a liquid to a solid.

The number of complete waves passing a point each second, measured in hertz (Hz).

A force that opposes the relative motion of surfaces in contact.

A safety device containing a thin wire that heats and melts when the current is too large, thereby breaking the circuit.

High-energy electromagnetic radiation emitted by a nucleus as it loses excess energy.

High-frequency electromagnetic radiation emitted from an unstable atomic nucleus.

High-frequency electromagnetic radiation emitted during changes in an unstable atomic nucleus.

A state of matter whose particles are widely spaced, move constantly and randomly, and spread out to fill their container.

The tiny atoms or molecules represented in the particle model of a gas.

Force exerted normally per unit area of a surface; gas pressure results from particles colliding with the walls of their container.

Pressure measured relative to atmospheric pressure; it is zero when the pressure equals atmospheric pressure.

A toothed wheel that turns about an axis and can transmit a turning effect to another gear through contact between their teeth.

A detector in which incoming ionising radiation causes electrical pulses that can be counted.

A device that converts the kinetic energy of a rotating shaft into electrical energy.

The production of an induced potential difference, and a current if the circuit is complete, by relative movement between a conductor and a magnetic field.