OCR GCSE Physics A Key Terms

The lowest possible temperature (-273.15°C or 0 K) where particles have minimum internal energy and zero kinetic energy.

When the energy of a wave is taken up by a material, often increasing its internal energy or temperature.

The material or object that takes in the energy transferred by the wave.

The process where a material takes in energy from a wave, transferring it to the thermal energy of its particles.

A continuous spectrum interrupted by specific dark lines, produced when cooler gases absorb specific wavelengths of light.

To change velocity over time, usually caused by a single resultant force.

The rate of change of velocity, measured in metres per second squared (m/s²).

The constant rate at which objects accelerate downwards towards Earth, typically taken as 9.8 m/s².

The steady rate at which an object's velocity increases as it falls towards Earth purely under gravity, standardly accepted as $9.8 \text{ m/s}^2$.

The constant rate at which all objects accelerate towards the ground under the sole influence of gravity ($10 \text{ m/s}^2$ on Earth).

A measure of how close a measurement result is to the true, actual value of the quantity being measured.

The rate at which a source of unstable nuclei decays, measured in Becquerels (Bq).

A safety device that inflates rapidly during a collision to increase the impact time, thereby reducing the resultant force on the occupant.

A conceptual vertical cylinder of air stretching from a specific point on the surface to the edge of the atmosphere.

The frictional force exerted by air against a moving object.

A contact force caused by the collision of fluid particles with a moving object, opposing its motion.

A measure of the proportion of incident radiation that an object reflects, ranging from 0.0 (perfect absorber) to 1.0 (perfect reflector.

A particle consisting of two protons and two neutrons emitted from an unstable nucleus, identical to a helium nucleus.

A highly ionising but weakly penetrating type of radiation that poses the greatest risk when inside the body.

A highly ionising particle consisting of a helium nucleus (two protons and two neutrons) with a low penetration power.

An electrical current that repeatedly reverses its direction of flow, used to produce radio waves in a transmitter.

An electric current that periodically reverses its direction and changes its magnitude continuously with time.

A type of electrical current that constantly changes direction, which is necessary for transformers to function.

An extra loop or branch in a parallel circuit that provides an additional route for charge carriers to flow from the power supply.

A type of electrical generator that produces alternating current (a.c.) using slip rings.

The vertical distance or height of an object or point in relation to sea level.

A device used to measure electric current in Amperes, which must be connected in series.

The standard unit of electric current, equivalent to a flow of one Coulomb of charge per second.

The standard unit of electrical current, equal to one coulomb of charge passing a point per second.

The SI unit of electric current, equivalent to one coulomb of charge passing a point per second.