One of my favourite experiments we ever did in my Physics classes at school was really simple, but also fascinating. I was reminded of it as I hugged my hot water bottle against the cold yesterday! It’s all about the way that heat is transferred through solids, which is called conduction.
We’ve covered similar topics here and here previously, so I’ll get right down to the experiment itself. To set it up you’ll need at least three bars, of equal diameter (around 0.5-1cm is good) and length but of different materials – like one metal, one wood and one plastic, but more is better, particularly if you can get several types of metal. If you want to try this yourself, why not ask the local hardware store to help, but be careful, this experiment gets hot!
Melt some candle wax and dip one end of each of the bars to the same depth. Leave to cool. Once they are cool you can set them up by a heat source. You could use a radiator or if you’ve got a proper experimental set-up in a lab, a Bunsen burner is normally used as it’s faster. Make sure that all the bars are in a secure position because they will get hot!
Then it’s time to get heating. Make sure that the heat is distributed evenly, and put some newspaper down underneath the bars. The molecules inside will start to conduct the heat down the bars, in some much more quickly than the others. Which do you think will lose all its wax first? Think about how free the molecules are to move and transfer their heat to their neighbours!