Energy and heating
Energy transfer
As well as transferring The capacity for doing work. 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 A material which allows charge to move easily through it..
All metals are good conductors. When one end of a metal rod is put into a fire, the energy from the flame makes the Electrically charged particle, formed when an atom or molecule gains or loses electrons. in the rod vibrate faster. Since the ions in the solid metal are close together, this increased Repeated movements back and forth (about a fixed point). 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 Per unit time or 鈥榩er second鈥. For example, if 2,000 J are transferred over a period of 10 s, then the rate of transfer is 200 J/s or 200 W. This value is the power rating. of transfer.
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Insulation
The cushion on a chair is an Material that does not allow charge or heat to pass through it easily.. A metal seat at a railway station will feel cold as it conducts energy away from the passenger鈥檚 body, whereas a cushion on the chair would not allow energy to flow so easily.