Conduction of heat
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When you leave a spoon in a cup of hot drink, the bit poking out of the drink gets hot. Why? Conduction! That's the easy bit - you probably know that is the way that heat travels through a solid. But how does conduction actually work? Hopefully, by the end of this short page, you will know and be able to explain it to someone else.
Metals are the best conductors of heat. This is because the atoms of metals are very closely packed together.
When you heat atoms, they start to vibrate more. So, if you heat the 3 atoms at the left hand end of the piece of metal in the diagram above, they wil vibrate more. This is shown below (orange shows the atoms that are vibrating more):
As these vibrate more, they bang into the ones next to them. This makes these atoms vibrate more than they were at first.
Then these atoms bang into their neighbours, making them vibrate more ... and so on. Eventually all of the particles are vibrating faster and so the whole piece of metal is hotter than at the start.
Which parts of the piece of metal will be hotter and why?
Click on the apple to reveal the answer
In liquids and gases, the particles are not fixed in place so this effect does not happen.
Metals are particularly good conductors of heat because their particles are very closely packed so the vibrations are passed on very quickly. They also contain large numbers of "free electrons". These drift slowly through the structure, giving metals their strength and other properties. As the metal is heated, the free electrons closest to the heat source are heated. This makes them move faster and they travel through the metal, colliding with both atoms and other electrons. This naturally makes these vibrate faster (or move through the metal faster - in the case of collisions with other free electrons). Thus the heat is passed quickly through the metal.