1. Not finding help here? Sign up for a free 30min 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!

Circuit Problem: Stored Energy

  1. Dec 14, 2008 #1
    1. The problem statement, all variables and given/known data
    We are given: R1= 1[tex]\Omega[/tex]
    R2= 2[tex]\Omega[/tex]
    L = 3 mH
    C = 500 [tex]\mu[/tex]F

    If the voltage is kept at 4V what is the energy stored in the circuit after it has reached a steady state. There is a link posted to the circuit provided below.

    2. Relevant equations
    energy stored in capacitor = 1/2Cv2
    energy stored in inductor = 1/2Li2

    3. The attempt at a solution

    Since you are given all the values you can just plug into the formula to find the energy stored in the capacitor. I got 0.004J. For the inductor I determined the current that flows through it which is 4V / 2[tex]\Omega[/tex] = 2A. I then used this value to compute the energy stored in the inductor, for that I got 0.006J. The total energy would be the sum of the two.

    This seems to be a simple problem but I'm just wondering if its a trick question since they want to know what the energy stored is after a long period of time.

    [​IMG]
     
  2. jcsd
  3. Dec 14, 2008 #2
    The energies (1/2)Li^2 and (1/2)Cv^2 are the steady state values for stored energy. You're result looks correct to me.
     
  4. Dec 14, 2008 #3
    Great thanks.
     
  5. Dec 15, 2008 #4

    CEL

    User Avatar

    Steady state means after an infinite time. Generally we consider that after 5 time constants the circuit reaches steady state. That is the meaning of a long period of time
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?