Physics key terms

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 high-speed electron emitted from a nucleus when a neutron changes into a proton.

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 that the universe developed from an extremely hot, dense early state and has expanded and cooled over time.

The model that the universe began in a very small, extremely hot and dense state and has expanded.

Fuel made from recently living material, such as plants or animal waste.

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 with gravity so strong that light cannot escape, which can form from the remnant of a very massive star.

The change from a liquid to a gas by boiling throughout the liquid.

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 a vehicle travels from when the brakes are applied until it comes to rest.

A force opposing a vehicle's motion while its brakes slow it down.

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.

Stationary conducting contacts that press against slip rings or a commutator to connect a rotating part to an external circuit.

Power transferred from an electrical cable to its surroundings by heating because the cable has resistance.

An estimate of the chance of harm based on data from a specified group over a specified period.

A scale whose markings have been matched to known values so that it can give measurements.

A relationship in which a change in one factor produces or contributes to a change in an outcome.

A single source of potential difference, shown by one long and one short parallel line.

A temperature scale on which the freezing point of water is approximately 0 °C and the boiling point is approximately 100 °C at standard atmospheric pressure.

The single point at which an object's weight may be considered to act.