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!

Homework Help: Equivalent circuit for non linear capasitor

  1. Sep 27, 2008 #1


    User Avatar

    what is the equivalent circuit for a non ideal capasitor?
    and if we have a parallel plate capasitor which consist of 2 metal plate of area A and held a distance apart d,we fill the region between the plate with a material with conductivity s and permitivity e.what is the inductance,resistance and capasitance of this system?

  2. jcsd
  3. Sep 27, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi EHT! Welcome to PF! :smile:

    Show us what you've tried, and where you're stuck, and then we'll know how to help. :smile:
  4. Sep 27, 2008 #3
    A partial list of the so-called elementry circuit elements, that I recall, are: voltage source, current source, R, L, C, and gyristor. --don't know much about this topic. The voltage source can be scratched if we can replace it with an infinite capacitor with initial charge. Same argument goes for the current source, replaced with an L-->infinity inductor and finite initial current.

    The question, as you stated it is very broad. Can there be hysteresis? Can C be a function of time? Is C a monotonic function of V or I?

    The most general condition I can think of off hand (ignoring probabliliy functions) is that C is a relation on t, V and I.
    Last edited: Sep 27, 2008
  5. Sep 27, 2008 #4


    User Avatar
    Science Advisor
    Gold Member

    Your description suggests a device that is linear. In what way is it non-linear?
  6. Sep 27, 2008 #5
    Yeah, I missed that, marcus.

    The first approximation of a capacitor is an ideal capacitor with a series resistor. This is quoted in the data sheets are ESR, effective series resistance. The leakage current, considered as a function of voltage, models as a resistor in parallel with the ideal capacitor. At high enough frequencies the lead lengths can be inductive and modeled with the addition of a series inductor.

    Memory effects are nonlinear.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook