Physics key terms

One of the two smaller nuclei formed when a large nucleus undergoes fission.

A circuit supplied with current that flows in one direction.

A source that provides a potential difference between positive and negative terminals to drive current around a circuit.

Slowing down: the magnitude of an object's velocity decreases.

The number of places written to the right of a decimal point.

The controlled closure and dismantling of a power station at the end of its working life.

A change in an object's shape or size caused by forces.

Mass per unit volume of a substance, measured in kilograms per cubic metre.

The variable measured in response to the change in the independent variable.

The physical change in which a gas changes directly into a solid without first becoming a liquid.

The vertical distance from a point in a liquid to the liquid's surface.

A unit formed by combining base units through multiplication or division, sometimes given a special name such as the newton.

A model that uses words or stated rules to explain how a phenomenon works.

A thin surface that vibrates when pressure variations in a sound wave reach it.

The unequal absorption of different wavelengths by a material.

Unequal absorption, transmission or scattering of different wavelengths.

Reflection from a rough surface that scatters light in many directions.

Describes an image that is smaller than its object.

A component that allows current to flow readily in one direction but has very high resistance in the reverse direction.

The unit of lens power, symbol D; one dioptre is one reciprocal metre.

A magnetic needle free to turn vertically as well as horizontally, so it can follow the local direction of Earth's magnetic field.

An electric current in which charge moves in one direction only.

Current that flows in only one direction, although its size may vary.

A circuit supplied by a direct potential difference, so conventional current travels in one direction.

The way in which a vector acts or points, stated using words, a bearing or a sign relative to a chosen positive direction.

The direction in which a wave and its energy propagate away from the source.

A relationship in which multiplying one variable by a particular factor multiplies the other variable by the same factor.