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temperature jumps



Still trying out all our new datalogging toys...

One of our current series of experiments measures heating and cooling
curves. They have an electric heater in the usual metal calorimeter block,
but with a Pasco temperature probe instead of the usual thermometer. This
sits in front of a fan to give constant convection conditions. The computer
logs temperature vs time and very beautiful curves appear... but...

Every now and then a section of the curve is displaced upwards. For a period
of about 5 minutes the temperatures recorded are about 4 degrees higher,
then they drop back down to be once again consistent with earlier
measurements. Obviously a measurement problem. Does anyone know what causes it?

Mark


Mark Sylvester
UWC of the Adriatic
34013 Duino TS
Italy
msylvest@spin.it