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but on a penny battery which is made of layers of: copper coin separated by cardboard soaked in vinegar and above a tin foil.
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In the examples I have seen
The copper coin is made of zinc coated with copper.
That coin is abraded on one side to expose the zinc.
Cardboard is soaked with a solution of vinegar and salt to create a combination of electrolyte with salt bridge.
The stack is as follows
penny copper side down - zinc side up
soaked cardboard
penny copper side down - zinc side up
soaked cardboard
penny copper side down - zinc side up
soaked cardboard
penny copper side down - zinc side up
soaked cardboard
penny copper side down - zinc side up
So in the second diagram you have
where it says electrolyte
that is where the soaked cardboard is located.
Also the diagram does not exactly show the alternation of zinc and copper as I mentioned
So I am not sure what is happening as compared to examples I have seen.
I have not done this -- I have only read it on line.