Physics key terms

The energy required to raise the temperature of one kilogram of a substance by one degree Celsius, measured in J/kg °C.

The energy required to change the state of one kilogram of a substance without changing its temperature, measured in joules per kilogram (J/kg).

The specific latent heat for a change between the solid and liquid states.

The specific latent heat for a change between the liquid and vapour states.

A line at a particular wavelength in a spectrum, produced or absorbed by a particular element.

A pattern of particular wavelengths emitted or absorbed by matter, used to identify shifts in light from a galaxy.

A display of the intensity of electromagnetic radiation at different wavelengths.

Reflection from a smooth surface in a single direction.

How quickly an object moves, without specifying a direction.

The speed at which all electromagnetic waves travel through a vacuum, approximately $3.00 \times 10^8\ \text{m/s}$.

A rotating contact divided into two halves that reverses a coil's connection to the external circuit every half-turn.

Fission that occurs without the nucleus first absorbing an incoming neutron.

A measure of a spring’s stiffness: the force needed per metre of extension while force and extension are proportional.

A circular path around another body in which the orbiting object stays at a constant distance from its centre.

A way of writing a number as $a \times 10^n$, where $1 \leq a < 10$ and $n$ is an integer.

A wave pattern on a vibrating string that appears to stay in place, with still points and moving sections.

A huge, hot body that produces its own light; the Sun is the star in our Solar System.

A physical form in which matter exists, such as a solid, liquid or gas.

An imbalance of positive and negative charge that remains on an object rather than flowing away continuously.

The accumulation of an overall positive or negative charge on an object.

An accumulation of electric charge that remains on an object rather than flowing away.

Not moving; on a distance–time graph this is represented by a horizontal line with zero gradient.

A wave pattern with fixed positions of no vibration and maximum vibration, formed by waves of the same frequency travelling in opposite directions.

A historical model in which the Universe expands but maintains the same overall appearance and average density over time.

A transformer for which the secondary potential difference is smaller than the primary potential difference.

A device that increases the potential difference of an alternating supply.

Removal or destruction of microorganisms so that equipment is safe to use.