Trouble of enormous magnitude

We have a problem brewing in the lab.  Recently, we (by which I mean a PhD student or two and a researcher) moved into a new lab. As part of our research we are recording electrophysiological signals (electricity produced by living cells). These are pretty small, often in the microvolt region (a millionth of a volt) – we’d consider a millivolt (a thousandth of a volt) a large signal. Getting good data in this situation isn’t easy – it needs some sensitive electronic equipment that is setup very carefully. For example, the way you earth something can make a big difference to the amount of electrical noise on your signal, and has to be done with some thought.  But, set it up correctly and it is possible to get decent recordings, which we are now getting.

Now, here’s the trouble. Another staff member is about to work with voltages on a vastly different scale – simulating lightning strikes on pieces of electronic equipment. And this experiment is due to be set-up in the lab next door to ours. The voltages experienced with lightning are in the kilovolt range (a thousand volts), a cool billion or so times bigger than the voltages we are trying to measure.  Needless to say that having that experiment sitting near our electronics doesn’t give us a good feeling.  It really is a problem of enormous magnitude – specifically about nine magnitudes.  (A magnitude being a factor of ten.)

The most obvious solution is to keep the two labs apart – perhaps a more practical one, given the  demand for lab space, is to put a Faraday shield around the lightning work. 

On the more light-hearted side, however, it does illustrate that electrical phenomena occur on a vast range of scales.



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