OCR GCSE Physics B key terms

The acceleration of an object falling under gravity alone; near Earth's surface its magnitude is approximately 9.8 m/s².

Closeness of a measured value to the true or accepted value.

The rate at which unstable nuclei decay in a radioactive source, measured in becquerels (Bq). One becquerel is one decay per second.

A graph showing how activity, count rate or the number of undecayed nuclei changes with time.

A conducting rod or wire used to transmit or receive radio waves.

A particle made of two protons and two neutrons, with mass number 4 and charge $+2$.

Current that repeatedly reverses direction.

An electrical supply whose polarity repeatedly reverses, causing the current in a connected circuit to change direction repeatedly.

A generator whose output potential difference repeatedly reverses polarity, producing alternating current in a complete circuit.

The maximum displacement of a point from its equilibrium position, measured in metres (m).

The angle between an incoming ray and the normal to the surface it meets.

The angle between a reflected ray and the normal to the reflecting surface.

The angle between a refracted ray and the normal to the boundary it has entered.

A result that does not fit the pattern formed by the other results.

The weight indicated when an object is supported while immersed in a fluid; it is reduced by the fluid’s upthrust.

A human-made object placed in orbit, such as a satellite orbiting Earth.

The pressure exerted by the air surrounding Earth.

The speed over a whole journey, equal to total distance divided by total time.

A favourable effect of a course of action, such as improved health, safety or quality of life.

A high-speed electron emitted from a nucleus during beta-minus decay, with mass number 0 and charge $-1$.

The scientific model that the Universe began in a very hot, dense state about 14 billion years ago and has since expanded.

The distance a vehicle travels from the application of its brakes until it becomes stationary.

One of the separate conducting paths in a parallel circuit.

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

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

A sequence of fission events in which neutrons released by one fission cause further nuclei to split.

A physical change between solid, liquid and gas in which the substance remains the same substance.