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Homework Help: Why voltage in a short circuit is 0?

  1. Jun 15, 2013 #1
    Why voltage in a short circuit is 0?

    I=U/R , R goes to 0, I goes to infinity => U=IR= 0 times infinity, i don't get it, why 0 "wins" here? Thank you!
  2. jcsd
  3. Jun 15, 2013 #2
    R goes to zero correct. So U must be zero so that current is finite. 1/0 is infinte 0/0 is finite.
  4. Jun 15, 2013 #3


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    2017 Award

    Staff: Mentor

    In real circuits, I is always limited in some way (by the power supply, for example). Usually this is more important than the tiny resistance of wires.
  5. Jun 15, 2013 #4
    Voltage is a measure of how much energy is needed to move charge from one point to another.
    If the resistance is zero then no energy is needed.
    Understanding of physics is the explanation, don't get tied up multiplying and dividing zeros and infinities.
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