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: GRE Problem LC circuit

  1. Oct 4, 2007 #1
    1. The problem statement, all variables and given/known data
    An AC source is connected to an LRC circuit (Inductor is connected to Capacitor in series, and then it is connected to register in series). Energy is stored in the capacitor and inductor and is dissipated in the resistor. At what time is the energy dissipated at the maximum rate?

    A. When the stored energy is all in electric fields
    B. When the stored energy is all in magnetic fields
    C When the stored energy is equally divided b/t electric fields magnetic fields
    D When no energy is stored
    E Under none of the conditions above

    2. Relevant equations
    Okay, frankly I have no idea. I tried thinking in terms of matching the impedance b/t capacitor and inductor. However, it doesn't really relate to the amount of energy stored in each devices.

    3. The attempt at a solution

    Maximum power output through the register means the maximum current through the registor. So the questions is, when will the current through the registor be maximum?

    Please, help!!
  2. jcsd
  3. Oct 4, 2007 #2


    User Avatar
    Homework Helper

    You won't need to get that fancy: this is a conceptual problem.

    Maybe this will help as a way to think about it. How does the current through the resistor behave as a function of time? (What does an LRC circuit do?) At the part of the process when the current through the resistor is greatest, what is going on at the inductor and capacitor? (Think about where the charge carriers, say, the excess electrons, are at that moment.)
    Last edited: Oct 4, 2007
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook