Edexcel GCSE Physics key terms

A wire used to carry current between the parts of a circuit rather than to provide a deliberate heating effect.

The principle that electric charge is transferred rather than created or destroyed, so the total charge remains constant.

The principle that energy cannot be created or destroyed; it can only be transferred between stores.

The principle that mass is neither created nor destroyed, so the total mass of a closed system remains constant during a change.

The principle that the total momentum of a closed system remains constant.

Motion in which equal distances are travelled in equal intervals of time.

A condition in which the temperature does not change between the initial and final states of the gas.

Velocity that does not change: the object has constant speed and travels in a straight line.

A condition in which the gas remains in a rigid container whose internal space does not change.

The part of an object's surface that is touching another surface.

A force between objects that are touching.

A chain reaction maintained at a steady rate: on average, one neutron from each fission causes another fission.

A movable component in a nuclear reactor that absorbs neutrons, allowing the rate of the chain reaction to be regulated.

A variable deliberately kept unchanged so that the effect of the independent variable can be investigated fairly.

Energy transfer caused by the bulk movement of a fluid, such as air or water.

The direction in which positive electric charge would move around a circuit, from the positive terminal towards the negative terminal.

A lens that brings rays travelling parallel to its principal axis together at a principal focus.

A numerical relationship used to change a measurement from one unit to another without changing the quantity represented.

A fluid that carries thermal energy away from the reactor core.

A graph showing how an object's temperature changes with time as it cools.

Earth's central region, associated with the source of its magnetic field.

Faint microwave radiation detected from all directions in space, understood as radiation left over from the hot early Universe.

Microwave radiation arriving from all directions in space, interpreted as cooled radiation remaining from the hot early Universe.

High-energy radiation arriving from space, including fast-moving particles from the Sun and beyond.

The SI unit of electric charge. One coulomb passes a point when a current of one ampere flows for one second.

The number of detections recorded by a radiation detector during a measured interval.

The number of events registered by a detector in a given time, often expressed as counts per second.