Physics key terms

A nucleus that can spontaneously emit radiation and change into a more stable nucleus.

An energy transfer that does not contribute to the device's intended output.

The resultant upward force exerted by a fluid on an immersed object because pressure is greater on its lower surfaces than on its upper surfaces.

The overall upward force exerted by a fluid on an object because pressure is greater on its lower surfaces than on its upper surfaces.

A particular form of uranium whose nucleus contains 92 protons and 143 neutrons, giving a mass number of 235.

Energy transferred in the way intended for the device or process.

An energy transfer that contributes to the intended purpose of a device or process.

Energy transferred in the form or to the store needed for the device's intended purpose.

The part of the input energy transferred in the way required for the device's intended purpose.

A region containing no matter.

The extent to which an investigation tests the intended effect because other relevant variables have been controlled.

A component whose resistance can be adjusted to control the current and potential difference in a circuit.

A quantity with both a magnitude and a direction.

An arrow used to represent a vector: its orientation and arrowhead show direction, while its length can show magnitude when drawn to scale.

A drawing in which arrows represent vectors by their direction and scaled length.

A quantity with both a magnitude (size) and a direction.

Speed in a stated direction. Changing direction changes velocity even if speed stays the same.

A graph showing how an object's velocity changes with time, with time on the horizontal axis and velocity on the vertical axis.

Callipers with a sliding scale that measure dimensions more precisely than an ordinary ruler.

The back-and-forth movement of an object or part of a material about its resting position.

An image formed where light rays appear to come from when traced backwards; it cannot be projected onto a screen.

The part of the electromagnetic spectrum that the human eye can detect.

The range of visible wavelengths which can be separated from white light into different colours.

The unit of potential difference; one volt is one joule of energy transferred per coulomb of charge.

The common name for potential difference.

An instrument that measures potential difference between two points and is connected across them.

The amount of three-dimensional space occupied by a gas, measured in cubic metres (m³).