Quote:
Originally posted by Since87
But, if the top and bottom of your waterblock are aluminum and copper, and they are bolted together using threads in the aluminum, then the electrical resistance between them is likely to be on the order of 0.001 Ohms or less.
Off the top of my head, I'll say the desired voltage differential between the copper and aluminum is 2V. Maintaining 2V across a 0.001 Ohm requires 2000 Amps. So doing this would require dissipating 4 KW in the joint between the copper and the aluminum. Kind of makes corrosion a moot point.
BTW, aluminum is more electronegative than zinc. You'd need to go to magnesium as your sacrificial anode.
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Ok, but you are missing a few things:
The limit is the salt bridge, not the direct connection between the two metals....ergo, the galvanic cell will not be producing a high current, and you will not need to send a high current in reverse.
You can easily add resistance to limit your current throughput to reasonable levels - just add a resistor in series, and you are done.
As for the Zinc/magnesium, you are correct - i looked at the potentials in seawater by accident - the potentials are very different
