initial conditions in a circuit

Discussion in 'Homework Help' started by jonirizo, Jan 19, 2013.

  1. jonirizo

    Thread Starter New Member

    Jan 19, 2013
    2
    0
    Can someone help me find the initial condition on this circuit for i(0)?
     
  2. tshuck

    Well-Known Member

    Oct 18, 2012
    3,531
    675
    Sure, but what's the fun in that?

    So, let's look at the problem... Before t=0, the switch is open, meaning the two resistors are a part of the circuit. We assume a steady state condition before t=0, so, what does an inductor act like at steady state when frequency = 0?

    An inductor acts as a short at steady state with a DC source, so the voltage across the inductor = 0 @ t < 0, so the current through the inductor is governed by the resistors. We know that the current through an inductor cannot change instantaneously, so the current through the inductor at t<0 is the current through the inductor at t = 0.
     
  3. jonirizo

    Thread Starter New Member

    Jan 19, 2013
    2
    0
    so the i(0) for this circuit will be :
    i(0)=6/(2+1) ?
     
  4. WBahn

    Moderator

    Mar 31, 2012
    17,743
    4,795
    6/(2+1) what? Amps? Megacoulombs? Ducks?

    If I tell you that a building is 300 tall, is it closer to 2 stories, 20 stories, or 60 stores (or something else entirely)?

    Units count!

    Your answer should be

    i(0+) = i(0-) = 6V/(2Ω+1Ω) = 2A
     
Loading...