Physics key terms

A magnet that produces its own magnetic field.

A direction at 90° to a surface; also described as normal to the surface.

The shortest distance from a pivot to a force's line of action, measured at right angles to that line.

A device that transfers energy from sunlight directly into an electrical pathway without a turbine.

A change in which no new substance is formed and the material can recover its original properties when the change is reversed.

A property that can be measured and expressed using a numerical value and a unit.

A sliding component that changes the volume of an enclosed gas when it moves inside a cylinder.

The point about which an object turns.

A natural object that orbits a star; Earth is a planet orbiting the Sun.

A very hot gas in which atoms have lost electrons, leaving charged particles.

A permanent deformation: the object does not return fully to its original shape and dimensions when the forces causing the deformation are removed.

A small, freely turning compass used to find the direction of a magnetic field at different positions.

A model in which an atom is a ball of positive charge with negatively charged electrons embedded throughout it.

An idealised charged object whose size is negligible compared with the distances being considered.

Which of two terminals is at the higher potential; reversing the polarity reverses the sign of the measured voltage.

An orbit that takes a satellite over or close to both of Earth's poles.

The state of an object that has lost electrons and therefore has fewer electrons than protons.

A positively charged ion formed when an atom loses one or more electrons.

A positively charged ion, formed when an atom or group of atoms loses one or more electrons.

The antiparticle of an electron: it has the same mass as an electron but a positive charge.

A medical imaging technique that detects radiation resulting from positron-emitting radiotracers inside the body.

The possibility that electromagnetic radiation could cause harm; the actual risk also depends on the exposure.

The difference in electrical potential between two points; it is the energy transferred per unit charge moving between them.

The energy transferred per unit charge between two points, measured in volts (V).

The energy transferred per unit charge between two points, measured in volts (V).

A series circuit that shares the supply potential difference between two or more components.

Energy associated with the positions of particles relative to one another and the forces between them.