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  1. mdjakhi
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    mdjakhi New EF Member

    Location:
    Canada
    Hi guys,
    How do you use ohms law on a circuit with 0 resistance? So, assume there is 10Amps and 0 Ohms on a circuit, how would you find the voltage? (E=IR?)

    Also assume you have a circuit with no resistance on it, where would be considered the return path? Like the potential difference I mean from hot to neutral.
     
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  2. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    because this is just a hypothetical question -
    no resisitance = no voltage !
     
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  3. David M
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    David M I'm often blinded by simplicity Electrician's Arms

    Location:
    Staffordshire
    There's no such thing as no resistance in an electrical circuit, much like there is no such thing as perpetual motion in mechanics.
     
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  4. Vortigern
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    Vortigern Electrician's Arms

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    England
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    F.H. Electrical
    Assuming it is a superconductor=0v
     
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  5. Marvo
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    Marvo GMES....You absolute beauty. YOU ROCK DUDE!!!! Staff Member

    Location:
    South Africa
    If the circuit has no resistance it's a perfect short circuit. This is only possible theoretically, not in the real world. With a zero resistance circuit the current flowing would in theory be infinite but in this case you'd need to look at the whole circuit including the source of the power, not just the final circuit that supplies the load because the internal resistance of the power source becomes the limiting element.
     
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  6. Des 56
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    Des 56 Trusted Advisor

    Location:
    Gliese 581C
    If you can hang on to this no resistance circuit,the world will rejoice at your feet
    The good and the great will bow down to you.untold riches will be bestowed upon you and your name will live long in the history books

    Somehow I fail to see that happening,probably a more accurate test meter may scupper this fantastic future
     
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  7. DPG
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    DPG Electrician's Arms

    Location:
    S Yorkshire
    In defence of the OP, it is a good question to ask. Hopefully the replies above have answered it! Daz
     
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  8. David M
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    David M I'm often blinded by simplicity Electrician's Arms

    Location:
    Staffordshire
    These type of questions get raised on many of the science forums I'm a member of.
    The problem is they often start with a premise that is not possible in the first place. So, yes I agree its a good question in that its quite easy to answer and understand. So long as its accepted that there is not always continuity between the hypothetical and actual reality.
     
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  9. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

    Location:
    cheshire/staffordshire
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    Telectrix
    if there were such a thing as zero resistance, my knees would allow me to get up off them in zero seconds, instead if the 2 minutes it takes now.
     
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  10. HandySparks
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    HandySparks Trusted Advisor

    Location:
    Hampshire
    Business Name:
    Neish Electrical Services
    That would be gravity, then. Get yourself a job as resident electrician on the moon; much easier.
     
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  11. telectrix
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    telectrix Scouser and Proud of It Trusted Advisor

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    cheshire/staffordshire
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    Telectrix
    if only:
     
  12. stummish
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    stummish Electrician's Arms

    Location:
    leeds
    If you get 0 ohms on a circuit contact CERN immediately to collect a free Nobel prize! Surely 0 ohms would give you infinate amps, and any PD on the circuit will trip in an infinaltely short time. Divide by 0 and the universe will implode, the ultimate PD!
     
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  13. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    Ignoring for now weather it is or isn't possible in practice,
    I always thought that to have a voltage ( or potential difference )
    then you need current flowing between two points
    with a resistance between these points.
    this is what gives you potential difference or voltage
    Am I correct or not ?
    SO NO RESISTANCE CAN ONLY = NO VOLTAGE ?
     
  14. Richard Burns
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    Richard Burns Trusted Advisor

    Location:
    Cambridgeshire
    Business Name:
    Richard Burns
    Yes V=IR so if R is zero, V is zero.
    There can be no voltage drop over a zero resistance, therefore no potential difference.
    i.e. the two ends of the zero resistance conductor are at the same potential.
     
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  15. dmxtothemax
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    dmxtothemax Regular EF Member

    Location:
    Australia
    Business Name:
    David Haddock Electronic Repairs
    Nuff said !
    Time for a beer or two or three.
     
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  16. charlie76
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    charlie76 Regular EF Member

    Location:
    Notts
    Business Name:
    CES Midlands
    No, you don't have to have a current flowing between the 2 points at all. The potential difference is the difference in potential between the 2 points. The potential to make a current flow between the 2 points. The resistance could be infinite between the 2 points and so no current is flowing but the potential still remains.

    2 cables held apart one at 50V and one at 0V, there is a 50V potential difference between them. Touch them together there is now no resistance between the two ends (in a perfect conductor) measure the voltage now 0V as there is no potential difference, they are both at the same potential, 50V, current will now flow. Obviously the current is restricted to the supply source and the resistances in the circuit.
     
    Last edited: Apr 24, 2017
  17. Dangerous Brian
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    Dangerous Brian New EF Member

    Location:
    Norfolk.
  18. stummish
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    stummish Electrician's Arms

    Location:
    leeds
    I didn't realise CERN has 0 resistance conductors. I know they cool it (gold? conductors) down to a few degrees off 0°K. If I had the time I'd look it up, interesting forum topic this has turned out to be!
     
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  19. Des 56
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    Des 56 Trusted Advisor

    Location:
    Gliese 581C
    It has been said that Superconductivity at room temperatures remains a very very very distant prospect (if it ever has been considered a prospect or even possible in the first place)
     
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