Physics key terms

An interpretation drawn logically from observations or data and supported by scientific reasoning.

A galaxy moving farther away from the observer.

Movement away from an observer, so that the distance between the source and observer increases.

The speed at which an object is moving away from an observer.

An expanded star formed after a Sun-sized star runs low on hydrogen in its core.

An increase in the observed wavelength of light compared with the wavelength at which it was emitted.

An expanded, very massive star that can later undergo a supernova.

The ray that travels away from a surface after reflection.

A wave returned when it meets a boundary or surface rather than continuing through it.

The bouncing back of a wave from a boundary.

The ray that travels through the second substance after crossing a boundary.

The change in direction of a wave as it enters a different material and changes speed.

A measure of how strongly a material slows and refracts light; a higher refractive index means that light travels more slowly in the material.

A solid with a simple geometric shape, such as a cuboid or cylinder, whose volume can be calculated from measurements of its dimensions.

A comparison of electric charge using proton charge as +1 and electron charge as −1.

The electric charge of a particle compared with the magnitude of the charge on a proton; a proton is assigned a relative charge of +1.

The mass of a particle compared with a chosen reference mass; at GCSE, the proton is assigned a relative mass of 1.

The ability of an energy resource to provide energy when it is needed.

An energy resource that is being, or can be, replenished as it is used.

An energy resource that is naturally replenished on a timescale comparable with its use, so it is not expected to run out in the foreseeable future.

The consistency of repeated measurements.

To exert a force that pushes objects away from one another.

A physical analogy or visual representation used to make selected features of a system easier to picture.

Obtaining similar results when an investigation is carried out again by another person or using different equipment or methods.

A force that pushes objects away from one another.

The opposition of a component to the flow of electric current, calculated by dividing potential difference by current and measured in ohms (Ω).

A component that opposes the flow of electric current.