Voltage and current relations for capacitor?

Discussion in 'General Electronics Chat' started by vead, Aug 15, 2016.

  1. vead

    Thread Starter Active Member

    Nov 24, 2011
    621
    8
    Hello
    I need help, I don't understand how to find out voltage of capacitor when voltage increase or decrease? I see the below formula. I plotted current time graph please help me
    IMG_20160815_155421.jpg
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    Is this homework?

    Your setup looks OK. What's the problem? What is the analytical expression for i(t)?
     
  3. crutschow

    Expert

    Mar 14, 2008
    12,984
    3,223
    You are asking to find the capacitor voltage when the voltage increases or decreases, which makes no sense.

    The capacitor voltage change is the integral of the current (which is the total charge) into (or out of) the capacitor over time.
    What don't you understand about that?
     
  4. vead

    Thread Starter Active Member

    Nov 24, 2011
    621
    8
    No I plotted graph just for my understanding. Any you asking the value of t1 and t2
     
  5. vead

    Thread Starter Active Member

    Nov 24, 2011
    621
    8
    Please look at formula, I want to find out voltage V
     
  6. crutschow

    Expert

    Mar 14, 2008
    12,984
    3,223
    Do you not know how to do the integration in the formula?
    That's how you calculate the capacitor voltage.
    If not then you need to start studying calculus.
     
  7. vead

    Thread Starter Active Member

    Nov 24, 2011
    621
    8
    Look at handy calculation
    IMG_20160815_224740.jpg
     
  8. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    The handy calculation omitted the 1/C term. Otherwise it looks good to me.
     
  9. DGElder

    Member

    Apr 3, 2016
    344
    85
    So what happened to C and Vo?
     
  10. WBahn

    Moderator

    Mar 31, 2012
    17,715
    4,788
    How did your i(t) suddenly go to just being t?

    On what basis, given the plot of i(t) you showed, are you claiming that i(t) = (1 A/s)·t between t = 2 s and t = 4 s?

    What happened to the capacitance?

    If you would bother to track your units (which I have warned you about repeatedly) you would have seen that the units on your answer don't work out to volts. The fact that you refuse to track your units only proves that you don't really care about getting the answer correct.
     
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