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Home Q & A Board Science-Related Homework Help Physics
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riveraj22 riveraj22
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11 years ago
I have an EDL Capacitor that stores the energy obtained from a certain chemical reaction. I need to calculate the amount of power generated by creating a voltage vs charge graph of the capacitor and finding its area. This means that I need to keep the multimeter connected constantly, but it can't decrease the charge stored in the EDL capacitor. How might I accomplish this? Thank you very much!
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#1
11 years ago
Most digital voltmeters are a couple million ohms impedance. If that's not good enough you can get or build something like the Trek 800 with almost infinite impedance.
http://www.trekinc.com/products/800.asp
wrote...
#2
11 years ago
If the capacitor is small, and I think this one is, from your comments, then you need a special very high impedance meter or amplifier.

It's easy enough to find opamps with input currents of 200 fA (AD8605 is one). At 10 volts, that is the equivalent resistance of 5e13 ohms or 50 Teraohms.

you can connect one of these as a voltage follower, and connect the output to a regular multimeter.

If 200 fA is not enough, then you need special equipment.
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leo123leo123
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#3
11 years ago
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#4
11 years ago
if a regular multimeter loads too much then you may need to get an electrometer

In my opinion Keithley makes the best, but I did not try all the makes and models

this is a good model

http://www.artisan-scientific.com/itemimages/Keithley_617_View1.JPG


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