Edexcel GCSE Physics key terms

A reduction in the intensity of radiation as it passes through matter.

To exert a force that pulls objects towards one another.

A force that pulls objects towards one another.

The mass of a whole object divided by its total volume, including any hollow or air-filled parts.

The total distance travelled divided by the total time taken.

The count rate measured without the radioactive source being investigated; it is the detector's reading due to background radiation.

The radiation present in the surroundings even when the source being investigated is absent.

Forces that combine to give a resultant force of zero.

A fundamental SI unit from which other units can be formed.

Two or more cells connected together to provide electrical energy.

The unit of activity; one becquerel is one nuclear decay per second.

A change of shape in which different parts of an object are displaced by forces acting at different positions.

A type of radioactive decay in which a neutron in an unstable nucleus changes into a proton and an electron is emitted.

A fast-moving electron emitted from an unstable nucleus.

A fast-moving electron emitted from a nucleus during beta-minus decay.

A type of radioactive decay in which a proton in an unstable nucleus changes into a neutron and a positron is emitted.

A fast-moving positron emitted from an unstable nucleus. A positron is the positively charged counterpart of an electron.

Radiation consisting of high-speed electrons emitted from unstable nuclei.

The model in which the Universe began in a very hot, dense state and has expanded and cooled over time.

Fuel made from recently living plant or animal material; it can be renewable when its supply is replaced at least as quickly as it is used.

A region formed by the collapse of a sufficiently massive stellar core, where gravity is so strong that light cannot escape.

The rapid change from a liquid to a gas throughout the liquid at its boiling point.

A conducting connection used to reduce a difference in charge between objects; during aircraft refuelling it helps charge pass safely to Earth.

The surface where one material ends and another begins.

Internal radiotherapy in which sealed radioactive sources are placed inside or next to a tumour.

The distance travelled from the moment the brakes begin to act until the vehicle stops.

One of the separate paths available to current in a parallel circuit.

A stationary conducting contact that connects the power supply to the rotating split-ring commutator.