Physics key terms

The balance between radiation absorbed by the Earth system and thermal radiation emitted into space.

The region around Earth where a magnetic object experiences a magnetic force. Its direction and strength vary with location.

The green-and-yellow striped safety conductor that is connected to exposed metal parts in an earthed appliance and normally carries no current.

A reflected sound wave that returns to a detector.

A method that sends out high-frequency sound waves and detects their echoes to locate underwater objects or measure water depth.

How well an insulating material reduces the rate of thermal energy transfer under specified conditions.

The fraction of the input energy transferred usefully, often expressed as a percentage.

The input force applied to a lever.

The property of returning to the original shape and length after the deforming forces are removed.

A collision in which total kinetic energy as well as total momentum is conserved. Real collisions are usually only approximately elastic.

Deformation in which an object returns to its original shape and size when the forces are removed.

A change in shape that disappears when the force is removed, so the object returns to its original shape.

The greatest load for which an object still returns to its original dimensions when the load is removed.

An object that can return to its original shape and size after the deforming forces are removed, provided it has not been deformed too far.

Energy stored when an elastic object, such as a spring, is stretched or compressed.

The energy stored when an object is elastically stretched, compressed or bent.

The energy store of an object that has been stretched or compressed and can return towards its original shape.

A device designed to transfer energy electrically from a power supply to one or more energy stores.

An electrical current or potential difference that varies with time to represent information such as sound.

A material in which charged particles, usually electrons in a solid, are free to move.

A material that resists the flow of electric current; covering a conductor with it helps prevent accidental contact.

A material in which electric charge cannot move freely, so charge transferred to its surface tends to remain there.

The separation of equipment from a source of dangerous potential difference.

Having balanced positive and negative charge, so that there is no overall charge.

Energy transferred per unit time, measured in watts (W).

The opposition of a component to the flow of electric current.

A pattern of changing current or potential difference that carries information, such as the pattern of a sound wave.