Energy and heating

Energy transfer

As well as transferring energy from one store to another, energy is transferred or transmitted from place to place. As it moves through a substance, energy is transmitted by conduction, convection or radiation.

Conduction

The aluminium base of a pan, the copper in the wires from a plug and the steel of a bell are all conductors.

All metals are good conductors. When one end of a metal rod is put into a fire, the energy from the flame makes the ions in the rod vibrate faster. Since the ions in the solid metal are close together, this increased vibration means that they collide with neighbouring ions more frequently. Energy is passed on through the metal by these collisions, transmitting the energy. More frequent collisions increase the rate of transfer.

Insulation

The cushion on a chair is an insulator. A metal seat at a railway station will feel cold as it conducts energy away from the passenger’s body, whereas a cushion on the chair would not allow energy to flow so easily.