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Suppose you do an electrolysis experiment, where you have

  • two carbon electrodes,
  • a battery,
  • and water in a which a strong electrolyte, like NaCl, is dissolved.

The circuit is closed and the electrolysis is going on. Then, after some time, you quickly remove the battery but leave the circuit closed.

My question is, what will happen to the current now? Will the current stop flowing immediately? Or will it continue for some time and then decrease until it stops completely?

My Assumption:

I assume that there will still be a current at least for a short amount of time because it takes some time for both electrodes to become equally charged again.

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    – andselisk
    Commented Apr 7 at 9:16

1 Answer 1

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This is a very good question! I'm not sure why you received a downvote. What you are asking about is called a polarization current.

Suppose we are electrolyzing a solution and suddenly we stop the current. It turns out that there is a weaker current flow in the circuit in the opposite direction. This phenomenon occurs at a measurable time scale. This was observed and discussed in the early 1800s. Current textbooks don't even mention this.

Actually, one can do a nice demo with a galvanometer. One can see the needle will deflect in the opposite direction the moment the battery is removed from the circuit during electrolysis.

You will need to get hold of older electrochemistry textbooks (pre-1930s) to see this experiment discussed in detail. Google Books will be the best source. One such book is Electricity in the Service of Man from 1890. It is freely available.

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