Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Node Voltage

  1. Mar 15, 2010 #1
    1. The problem statement, all variables and given/known data
    Find the node voltage

    2. Relevant equations

    Va = Vb x R1/(R1+R0)

    3. The attempt at a solution

    I didnt have the original picture of the question but this example is exactly same as the question that i had to solve. but I dont understand this thing from the first step.
    How can Vb = Va x (4//4)/(4//4+2)? I know that the 2ohms at the right side of circuit can be added as series and fucntions as 4ohm and it is paralle to 4 ohm in the middle. and so the total resistance of the circuit is 4//4 +2, but why do we use 4//4 to find Vb? isnt it just 2ohm in front of Vb that we have to use?
    Help please

    Attached Files:

    • 1.jpg
      File size:
      21.8 KB
  2. jcsd
  3. Mar 15, 2010 #2


    User Avatar
    Homework Helper

    What does the symbol // (as in 4 // 4) mean?
  4. Mar 15, 2010 #3
    There are alot of ways to analyze circuits and its been alittle while for me. That being said the easiest way to find Vb would be to find the resultant resistance of the right hand side/loop of the circuit. Since it turns out to be equal to 2 ohms then you have two resistors in series that are both 2 ohms. Thus the voltage drops will be equal to each other and be 1/2 of the source voltage or 3 volts.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook