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!

Question on voltage in Thevenins circuit

  1. Feb 8, 2014 #1

    What happens to the 30V voltage when it arrives at node V1? Does any voltage "flow" in the yellow part of the circuit? In other words what would be the voltage across the 10 ohm resistor at the top?

    I know that no current flows in the yellow part of the circuit so I am assuming its the same for voltage?
  2. jcsd
  3. Feb 8, 2014 #2


    User Avatar

    Staff: Mentor

    Voltage does not flow. Voltage is a potential with respect to some reference point. Here the reference point is the bottom rail with the ground symbol attached. So voltage does not "arrive" at some location; it's just the potential at that location.

    Potential changes occur as a result of current flowing though some resistance. If no current flows, then no potential drop happens and the potential (voltage) remains unchanged.

    In this problem determine where and how much current flows. Calculate the potential drops that occur for the current passing through each resistor.
  4. Feb 8, 2014 #3
    Well, to be honest, the 30V voltage won't "arrive" at the node V1. Not all of it, anyway. Voltage doesn't flow either, but I understand what you mean.

    You have three 10k ohm resistances, no 10 ohm resistances and you have two resistances at the top. Please clarify what you mean.

    For your last question, use ohms law. U = R * I.

    Edit: Didn't see gneill's response. You're in good hands, influx.
  5. Feb 8, 2014 #4
    I phrased that quite badly lol. What I mean is is the voltage along the yellow wire equal to 0? I know that the voltage across the first 10 ohm resistor (the one closest to the voltage source) is 15V. Same applies for the second resistor in that loop but that's as far as I have got.
  6. Feb 8, 2014 #5


    User Avatar

    Staff: Mentor

    If no current is flowing then no potential change can occur: it remains constant. So the whole branch in yellow must remain at the same potential as where it connects (the junction you've labeled V1).
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Question on voltage in Thevenins circuit