The problem is an experiment has to be set up to investigate how the breakdown voltage (which occurs by a large reverse potential difference is applied to the diode, and the diode then passes a large current) of a semiconductor diode is affected by temperature. My problem is how can I vary the temp. of the diode in the range of minus 70 degrees C to 150 degrees C, whihc is what the question asks for, I think I can get a range of about -10 celcius to 70 degrees , but I also want to ask whether it is safe to submerge the diode in hot water (which will be heated by a bunsen burner)? Also how can I set up a circuit so that the breakdown Voltage is calculated BUT also avoid large currents (which would cause damage to the diode when breakdown occurs) <- this is probably the most important bit. # THANKS to anyone with any ideas and suggestions!