6th Grade Project

Thread Starter


Joined Jan 23, 2005

My 12 year old son is in need of setting up an experiment for his science class. They must come up with their own idea, and his is which fruit will allow the most electrical current through it. He'll test a half dozen or so different fruits for this. Unfortunately, his father is not at all knowledgeable with electricity. The only thing I know to do with my multi-meter is to measure wall outlets to see if they are alive or not. I have attached a picture of my multi-meter. Would someone know how we could start and set up this project using a small battery, wires, and multi-meter, etc. Some explanation on how to use my multi-meter would be much appreciated.




Joined Apr 20, 2004

The attached circuit is the simplest for doing the measurement. Move your red lead to the "ma" socket, and put the selector to the 200 ma setting in the DC A range.

Be aware that there are more variables here than trees have leaves. This setup measures bulk conductivity rather than true resistance. That, however, won't invalidate the measurements.

Do use copper wire to connect to the fruit. If you use the meter lead and a wire, the dissimilar metals will make a small battery and affect the reading in unpredictable ways. A better methodology would be to make a uniform slice per fruit, and measure through each one. Otherwise, a grapefruit will always look less resistive (more conductive) than a tangerine simply because of volume, rather than any inherent difference between grapefruit and tangerines.