Seebeck’s couples
Accurate temperature measurements from an often misunderstood instrument
How do you teach practical thermodynamics without a lab? While virtualisation and data analysis capture some aspects of the scientific process, they lack the messiness, fiddliness and ambiguity of actual lab work. However, the requirement to keep students apart in a time of pandemic risks further curtailing hands-on time.
It was this question which led us, at University College London, to imagine giving our first year students a chemistry set with which to do experiments. For most people, chemistry sets evoke the idea of bottles of exciting chemicals. Yet just as using a Berlitz phrasebook allows you to ask simple questions in an unfamiliar language but leaves you at sea for the answer, chemicals on their own don’t allow you to get into the real structure of chemistry.
Instead we imagined providing instruments, with the slogan: ‘If you can measure one substance, you can measure them all’. Central to the kit we would place the most mysterious and misunderstood item in the chemistry laboratory: the thermocouple. Ask the average scientist how it works and they will mutter something about a voltage that occurs when two metals are placed in contact to form a junction. This is wrong, and rather confuses two effects, both discovered by Alessandro Volta.