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Q & A: citrus conductance

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Most recent answer: 10/22/2007
Q:
I am doing a science fair project on which citrus fruit will conduct electricity an I was wondering what you thought on the subject and if you could help me out. Thanks
- chris (age 13)
Brunswick, Georgia, United States
A:
This is mostly an experimental question, but here are some thoughts which might help:

0. When you compare different fruits, you'll need to be careful to have the same length of wires in them, at the same distance.

1. The electrical resistance will come partly from cell walls, which are hard for the (electrically charged) ions to cross. I bet you'll get different numbers for conductivity if you meaure juice or fresh fruit. Mushed-up fruit may be in-between.

2. If you measure resistance with a standard dc meter, there will be some charging effects at the wires. That may increase the resistance. If you can find an ac resistance meter, that would work better.

That's all I can think of for now.

Mike W.

I'll be willing to bet that a lot of variation can be in how good the contact is between the wires and the fruit. The contact resitance should be inversely proportional to the surface area of contact, and this really means the amount of contact that's wet. So make sure you stick the probes or wires the same distance into the fruit or juice.

Tom

(published on 10/22/2007)

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