Key ideas in physics key terms

Energy transfer (cross-unit)

Movement of energy between stores or pathways; link to electricity, forces, waves and radiation contexts.

Field (cross-unit)

A region where a force can act without contact, including gravitational, electric and magnetic fields.

Model (cross-unit)

A simplified representation that explains observations, such as particle, wave, atomic and cosmological models.

Proportionality

A mathematical relationship where one quantity changes predictably with another, such as force and extension within the limit of proportionality.

Gradient

The rate of change on a graph, such as speed on a distance-time graph or acceleration on a velocity-time graph.

Potential difference

Energy transferred per unit charge; connect electricity, fields and transformer contexts.

Wave speed

Distance travelled by a wave per second, linked to frequency and wavelength.

Resultant force

The single overall force after forces in different directions are combined.

Conservation

A principle that a quantity, such as energy or momentum, is not created or destroyed in a closed system.

Evidence

Data or observations used to support a model or explanation, such as red shift and cosmic microwave background radiation.