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

Constraint on Thevenin impedance

  1. Jul 12, 2011 #1
    Let's say we have a circuit composed of simple linear circuit elements (resistors, inductors and capacitors). Now we calculate the Thevenin equivalent circuit for some load within this circuit, and we determine the Thevenin impedance, Z_t.

    My question is this: Is it generally the case that the real part of Z_t is positive (Re Z_t greater than or equal to zero)? In particular, has this been proven to be generally the case?

    Thanks for any help, Patrick
  2. jcsd
  3. Jul 15, 2011 #2
    Last edited by a moderator: Apr 26, 2017
  4. Jul 15, 2011 #3


    User Avatar
    Science Advisor

    Hi Patrick. The simple answer is that for linear circuits containing only independent sources then yes the real part of the Thevenin impedance is non-negative. However for circuits containing dependent sources the Thevenin resistance may be negative.
    Last edited: Jul 15, 2011
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook