Physics key terms

A unit formed by combining two or more units, usually by multiplication or division, such as metres per second.

The ability of a substance to be forced into a smaller volume.

A region of a longitudinal wave where the particles of the medium are closer together than usual.

A model run by a computer to apply rules and calculations, often repeatedly or to many interacting parts.

A lens that spreads rays travelling parallel to its principal axis apart.

The change from a gas to a liquid.

The transfer of energy through a material from a region at higher temperature to a region at lower temperature, without the material moving overall.

A material, such as a wire, through which electric charge can flow.

A thin part of a loudspeaker or headphones that vibrates and causes the surrounding air to vibrate.

Keeping hot fusion fuel in a region where it can react without touching and damaging the surrounding vessel.

A third variable that affects both variables being studied and can therefore create or alter an apparent correlation.

A wire used to carry current between the parts of a circuit rather than to provide a deliberate heating effect.

The principle that electric charge is transferred rather than created or destroyed, so the total charge remains constant.

The principle that energy cannot be created or destroyed; it can only be transferred between stores.

The principle that the total mass of a closed system remains constant during a change.

The principle that the total momentum of a closed system is the same before and after an interaction.

Acceleration that remains unchanged during the motion being considered.

Motion in which equal distances are travelled in equal intervals of time.

A condition in which the temperature does not change between the initial and final states of the gas.

Velocity that does not change: the object has constant speed and travels in a straight line.

A condition in which the space occupied by the gas does not change.

The part of an object's surface that is touching another surface.

A force between objects that are physically touching.

An interaction that occurs only while the objects are touching.

An unbroken range of wavelengths and frequencies, rather than radiation at only a few separate values.

An unchanged comparison used to show what happens without the treatment being investigated.

A chain reaction maintained at a steady rate: on average, one neutron from each fission causes another fission.