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Finally, discuss some physical limitations that might

  1. Feb 6, 2013 #1
    "Finally, discuss some physical limitations that might ..."

    1. The problem statement, all variables and given/known data

    Part (d) of problem 1 here: http://faculty.washington.edu/joelzy/402_502_W13_hw4.pdf [Broken]
    2. Relevant equations

    I have (I(t) I'(t))T = cos(t/√(LC))k1 + sin(t/√(LC))k2, some k1, k2 ε ℂ2 for my solution and so I know that decreasing the value of LC increases the ticking frequency of this clock.

    3. The attempt at a solution

    But I'm at a loss for what to put for this "discuss some physical limitations" thing. Thoughts?
     
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Feb 6, 2013 #2

    rude man

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    Re: "Finally, discuss some physical limitations that might ..."

    For one thing - do you think this clock will run forever? Even if so, does the current level stay constant or does it get harder to detect over time? Do the values of R, C and L change in any way over time?
     
  4. Feb 6, 2013 #3
    Re: "Finally, discuss some physical limitations that might ..."

    Theoretically, yes.

    Well, it oscillates, since current is V = RI, R is constant, I is oscillating.

    I don't really know since I'm not an electrical engineer
     
  5. Feb 6, 2013 #4
    Re: "Finally, discuss some physical limitations that might ..."

    I do not see any dependence of the solution on R. How come?
     
  6. Feb 6, 2013 #5
    Re: "Finally, discuss some physical limitations that might ..."

    If we want it to tick with a constant frequency, then we want the node to be a center, so we want R=0. Right? We want I(t)=0 periodically.
     
  7. Feb 6, 2013 #6

    rude man

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    Re: "Finally, discuss some physical limitations that might ..."

    Does it seem reasonale to assume that whatever circuit you use to detect the zero crossings of the current has a limitation as to how low the current can be before it can't tell the difference between that low level and zero?

    And BTW you can't have R = 0 in real life. Besides, the problem specifies a resistor.

    And FYI R, C and L do change over time & environment. That's why crystal oscillators are used in your PC!
     
  8. Feb 6, 2013 #7
    Re: "Finally, discuss some physical limitations that might ..."

    Do you think it is physically possible to have R = 0? The circuit is called LRC for a reason.
     
  9. Feb 6, 2013 #8
    Re: "Finally, discuss some physical limitations that might ..."

    Isn't my intuition right, though, that we want the vector field of (I I')T to be something circling the origin forever?
     
  10. Feb 6, 2013 #9
    Re: "Finally, discuss some physical limitations that might ..."

    Is that possible with R > 0?
     
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