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!

Equivalent impedance

  1. Apr 14, 2006 #1
    see diagram http://img.photobucket.com/albums/v11/biggm/z.jpg [Broken]

    The question is to find the equivalent impedance for the circuit.

    I am not sure how to solve this, it is simple in the case of all three elements in series but with the capacitor in parallel i am not sure how to solve it.
    thanks for the help
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Apr 14, 2006 #2

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    Find the impedance of the inductor and resistor in series. Then find the impedance (pure reactance) of the capacitor in parallel. Then add the impedances using:

    [tex]\frac{1}{Z_{total}} = \frac{1}{Z_1} + \frac{1}{Z_2}[/tex]

    It gets a little difficult because the impedances have phase differences.

    [tex]\frac{1}{Z_{total}} = \frac{1}{\sqrt{R^2 + \omega^2 L^2}} + \omega C[/tex]

    Last edited by a moderator: May 2, 2017
  4. Apr 14, 2006 #3
    An equivalent alternative is to say,

    [tex] Z_r = R [/tex]

    [tex] Z_c = - \frac{j}{ \omega C} = \frac{1}{j \omega C } = \frac {1}{\omega C } \angle {-90^o} [/tex]

    [tex] Z_L = j \omega L = \omega L \angle {90^o} [/tex]

    Then treat the R-L in series, and call it [itex] Z_{RL} [/tex]

    and make that in parallel with [tex] Z_c[/tex],

    which gives you: [tex] Z_{eq} = (Z_c \backslash \backslash (Z_r + Z_L) ) [/tex]
    Last edited: Apr 14, 2006
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Equivalent impedance
  1. Are these equivalent? (Replies: 5)

  2. Equivalent Impedance (Replies: 6)

  3. Equivalent impedance (Replies: 1)