Return of an old classic
It was a wet weekend so I went down to the lab to play with the apparatus. Years ago I broke the lamp that is used in the Stefan Boltzmann experiment, never got around to replacing it but discovered that it's just a car side-lamp so found one in my garage and replaced it. The thermopile was still in its drawer so I set the apparatus up to see if it still worked. The Stefan Boltzmann Law is pretty important in several areas of the syllabus so thought this might be a good practical to reintroduce. The only problem is that I only have one and I have rather gone off the idea of circuses of experiments over the past few years. Maybe I can get some cheap IR sensors from Ebay? As you can see I'm using a Pasco set up which comes with a handy manual that includes a table to convert the resistance of the filament into temperature, all you have to do is measure the current and voltage. I quickly ran through the range of voltage offered by my power supply and came up with a nice curve. To test the power 4 relationship I decided to plot a log log graph and got the results shown below.
Amazingly close with a gradient of 3.793, not bad considering the time spent taking measurements. At first I was surprised by the large negative gradient but of course the constant of proportionality is very small making the log of it -ve.