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Homework Help: Very basic circuits 1 question. Charge and current

  1. Oct 2, 2014 #1
    1. The problem statement, all variables and given/known data
    Find the charge q(t) flowing through a device if the current is: 20 cos(10t + π/6)μA, q(0) = 2 μC

    2. Relevant equations
    ∫ i(t)dt +q(0)

    3. The attempt at a solution
    I am studying for a test by working all the problems I can and then looking at the solutions manual. The solutions manual says the answer is (2sin(10t+π/6)+1)μC. I got the same thing except +2 at the end since q(0) is 2. It's really bugging me that I can't figure out why. Can anyone please explain?
  2. jcsd
  3. Oct 2, 2014 #2

    Doc Al

    User Avatar

    Staff: Mentor

    If you plug in t = 0 to your solution and the manual's, which one gives the correct answer?
  4. Oct 2, 2014 #3
    Ahh, got it now. Thank you. I didn't realize that's what it meant. I was just adding the q(0) but I didn't realize until you pointed it out that the entire function in itself is q.
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