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: Series R and LC circuit question

  1. Jul 25, 2010 #1
    1. The problem statement, all variables and given/known data

    Since I dont have a pic.. I will explain my problem. I have a circuit with 3 terminals x , y and z.
    Between x - z I have a resistance , say R,
    Between z - y I have an inductor L and then a capacitor C in series.
    I apply a square wave input between x and y.

    2. Relevant equations

    How will the voltage at output look like? and why does it look like it? output terminals being z-y.
    3. The attempt at a solution

    I already know the answer except I cant understand it. Answer being, Vzy would be discontinuous. So far, I have , at the rising edge of the square wave, an impulse current would be across L, now I dont understand how the capacitor will react. can someone explain it? so how would Vzy be discontinuous?
    Last edited: Jul 25, 2010
  2. jcsd
  3. Jul 25, 2010 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    The current through an inductor is always continuous, and the voltage across a capacitor is always continuous. Does that help?
  4. Jul 31, 2010 #3


    User Avatar

    Since the three elements are in series, the current is the same in all three. Write the equations of voltage as a function of the current for the three elements. The sum of the voltages is the input square wave, or a series of positive and negative steps.
    Solve the resulting integral-differential equation, to obtain the current in the circuit.
    Having the current, you have the voltages in the inductor and capacitor.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook