1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electric potential and earth/ground

  1. May 6, 2012 #1
    I was just wondering if the following is true/possible:

    - Could a circuit be made that is connected from a terminal on one battery, through a load, and then connected to the opposite terminal of another battery, where the batteries aren't touching?
    I believe it isn't possible, but would someone be able to give a quick explanation as to why this doesn't work?

    - What role does an 'earthing' or 'grounding' have in a circuit where there is an power source and then a return path to the source as well as a grounding?

    - On that note, could someone please clear up exactly how circuits with a grounding in them work in general?
    Circuits like this seem to defy the notion that "a circuit must be closed for current to flow"

  2. jcsd
  3. May 6, 2012 #2
    This is an example of a circuit that I'm talking about 'denying the notion that "a circuit must be closed for current to flow"'
  4. May 6, 2012 #3
    Yes, its not possible, unless there is some excellent conducting medium between the batteries for the flow of electrons. :wink:

    To set up a potential difference in a battery, it requires a continuous flow of charge. Now if two separate batteries are connected to the load, the electrons from the first battery have no where to go and complete their loop, and are basically just stuck. So, no current.

    As for grounding,
    http://en.wikipedia.org/wiki/Ground_(electricity [Broken])

    Earth here acts as a -huge- conductor(reserve) of electrons, so the circuit is complete.
    Last edited by a moderator: May 6, 2017
  5. May 6, 2012 #4
    Wait.. So you're saying it is possible? I thought it would be fundamentally impossible...
    Fill me in...

    This is what confuses me about grounding, it seems as if they cannot complete their loop. Could you elaborate a bit?
  6. May 6, 2012 #5
    It is possible IF you get a way to transfer electrons between the two batteries. That is by a wire, or a medium like aqueous sodium chloride, etc. This is equivalent to just touching the two batteries. Only difference being that you dont physically touch them, you just give them a way of transferring their electrons.

    As I said in my above post, the earth acts as the conductor/reserve of electrons. So electrons from the source can go to and through the earth, just as if it were a wire. Or, if used as a lightening conductor, earth acts as a reserve (though in the broader sense, a conductor) and takes in all the electrons.
  7. May 6, 2012 #6
    Ok, so are you saying the electrons just don't return to the power source?
    Could you set up a circuit that goes :
    [negative terminal of battery] --- [Load] --- [earth]
  8. May 6, 2012 #7
    Oh no. Not at all. I was just reasoning why grounding works. The lightening conductor case is irrelevant. :redface:

    From wikipedia
    So yes, you do have to return to the power source. The grounding is just the way for it to happen.
  9. May 6, 2012 #8
    Ohhh okay!
    That clears things up. I was making it too complicated for myself...
    Thanks for your patience :P
    Have a nice day/night (depending on where you are in the world)
  10. May 6, 2012 #9
    My pleasure :smile:

    Have a good *insert time of the day here* too. :wink:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook