1. Not finding help here? Sign up for a free 30min 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!

Basic Ciruits , dependent sources

  1. Feb 7, 2013 #1
    1. The problem statement, all variables and given/known data

    https://www.diigo.com/item/image/2sb3i/1svo [Broken]

    Why don't we flip the signs of VA like this :

    https://www.diigo.com/item/image/2sb3i/g2a4 [Broken]

    because the current must flow from + to - of the resistor.

    2. Relevant equations
    none


    3. The attempt at a solution
    none
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 7, 2013 #2

    gneill

    User Avatar

    Staff: Mentor

    The "+ -" tags on the 15Ω resistor tell you which way to "measure" the potential VA; It's like specifying how to orient the positive and negative leads of a voltmeter on the component.

    You could change the tags as you suggest IF you also reverse the polarity of the controlled voltage source 2VA, since its output depends on how VA is "measured".
     
  4. Feb 7, 2013 #3
    thanks
    and the KvL equation changes from :
    -120+V30+2VA-VA = 0

    to :
    -120+V30-2VA+VA = 0
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Basic Ciruits , dependent sources
Loading...