4.9 Key ideas

The complex and diverse phenomena of the natural and man-made world can be described in terms of a small number of key ideas in physics.

These key ideas are of universal application, and we have embedded them throughout the subject content. They underpin many aspects of the science assessment and will therefore be assessed across all papers.

Key ideas in physics include:

  • the use of models, as in the particle model of matter or the wave models of light and of sound
  • the concept of cause and effect in explaining such links as those between force and acceleration, or between changes in atomic nuclei and radioactive emissions
  • the phenomena of ‘action at a distance’ and the related concept of the field as the key to analysing electrical, magnetic and gravitational effects
  • that differences, for example between pressures or temperatures or electrical potentials, are the drivers of change
  • that proportionality, for example between weight and mass of an object or between force and extension in a spring, is an important aspect of many models in science
  • that physical laws and models are expressed in mathematical form.