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Science Fair Project
Project Background

It has been many years since I was last reminded that I once participated in the Science Fair program in Elementary School. Based on the metadata of the few images that I have left over from my science fair project, I can see that it took place during the first half of 2007, so I must have been nearing the end of my fifth-grade year. From what I can remember, I didn’t end up running with the same project that I set out to do. My original plan was to power a light through electrical potential energy drawn from a lemon. At the time I knew that it was possible, but I didn’t know the method’s necessary for doing so and wanted to learn them. However, it was pointed out to me that this isn’t really a test in any way, with hypothesis, testing and conclusions, so my dad and I adjusted the idea to instead test the electrical conductivity of different fruits and draw conclusions as to why these differences existed.

We performed tests on a lemon, orange, lime, pineapple, apple and banana, using a voltmeter and 1.5-volt battery to test the current that was allowed through each fruit, effectively solving for the resistance value of the fruit. The results that we obtained were confusing, so we also re-tested the citrus fruits after crushing them and designated those trials to be the “special” fruits. We realized that the membranes separating the cells of the fruits were insulating and preventing current from passing through, making pineapple the most conductive fruit because of a lack of these membranes. We had hypothesized that the lemon would be the most conductive, and after crushing the internal cell membranes, it was. The crushed lime closely followed.

At the time I was unfamiliar with the exact nature of voltage, current, resistance and the mechanism behind citrus fruit conductivity, but I thought that there would be a positive correlation with the “tartness” of the fruits. At the fair, I explained my theories and why our original hypothesis was thwarted by the structure of citrus fruits. At the time, my dad explained the chemistry and physics behind these phenomena to me, and I ended up with a basic understanding of the processes at work. I was awarded a gold 1st place ribbon, however there was no competition at the fair, so I assume that the award corresponds to the perceived amount of work put in and how well the presenter understood the topics involved in their experiment. I’m glad that I participated; it was an intriguing experiment that’s fun to look back on, and it was my first introduction to any kind of circuitry.

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