|MadSci Network: Physics|
If you are doing an experiment one some of the more important things to do are: Work out just what you are testing for, or work out your hypothesis. Devise the experiment such that only one variable changes. Keep everything else constant. Here you want to find out if temperature somehow changes the output of a photo voltaic cell. What this means is you want to keep everything constant except the temperature. I suggest the important thing here is to make sure your amount of light falling on the cell is constant, but only change the temperature. Get a cheap solar cell (like the kind in calculators etc). Find out the sort of out put it nominally has - both its rated current and voltage. Then rig up a simple circuit - solar cell and resistor. Here just make sure the resistor is suitable such that at the rated output of the solar cell you get a suitable current (remember V=IR). Now maybe use a lamp as you light source - preferably a flourescent as they have a low heat output, or maybe even a battery driven torch (to make the whole thing transportable). Rig up a box and light with the solar cell to stop other external light sources from messing up your experiment. Now you need to measure the voltage output of your cell under varying temperatures (you know the load so V=IR will also give you current). You will need to measure the temperature here aswell. One problem you may need to overcome is that resistance of your load may also change with temperature. Som maybe isolate your load from the solar cell (e.g. with really long wires). If you have a fairly simple setup (e.g. solar cell strapped to the front of a torch, wires leading away to a load across which you measure the voltage), you could do things like stick the solar cell part of this circuit in the freezer, wires leading outside the freezer to your load, put an accurate volt meter across the load, let it come to thermal equilibrium (wait a while) then take your measurements. These are just some ideas. The thing is to experiment with it all. Martin Smith
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