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Homework Help: RL Circuit

  1. Apr 5, 2016 #1
    1. The problem statement, all variables and given/known data
    Find i and v_x
    Given answer:

    2. Relevant equations

    3. The attempt at a solution
    I have attempted the problem in two different manners, and I consistently reach a different answer. I would appreciate if someone would be willing to take the time to attempt the problem and confirm whether the provided solution is correct.

    My answer:
    i(t) = 5* e^(-5.6*t)
    I have not attempted to solve for v_x yet, because I want to verify the first part of the answer.

    Method 1: Apply KVL directly to the circuit

    Method 2: Find the equivalent resistance at the inductor terminals with a test voltage source.
    I am not showing the work for this method, but I did it this way as well and received the same answer as my first attempt.

    If my attempt is wrong, I really would appreciate some insight into where I went wrong.
  2. jcsd
  3. Apr 5, 2016 #2


    User Avatar

    Staff: Mentor

    I think your result looks better than theirs! Considering that they used the unit V for both voltage and current in their answer, I suspect that they have an editing issue with the answer key.
  4. Apr 5, 2016 #3
    Good point, I completely managed to overlook that! I just couldn't find this listed in the errata for my book so I blindly trusted it.
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