voltage drop

Discussion in 'Homework Help' started by myoplex11, Oct 3, 2007.

  1. myoplex11

    Thread Starter New Member

    Oct 3, 2007
    5
    0
    A 6V DC voltage source is connected across both a 5kohm resistor and a 10 nF capacitor in series. The voltage drop across the resistor is what?
     
  2. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    v(t) = V*exp(-t/RC)

    V = voltage at source
    R = resistance
    C = capacitance

    Dave
     
  3. myoplex11

    Thread Starter New Member

    Oct 3, 2007
    5
    0
    thanks but the time is not given
     
  4. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    From the above equation the voltage across the resistor is a function of time, so it is pretty essential to the question - could it be asking you for the initial or final voltage across the resistor?

    Dave
     
  5. myoplex11

    Thread Starter New Member

    Oct 3, 2007
    5
    0
    it is the final voltage across the resistor
     
  6. Dave

    Retired Moderator

    Nov 17, 2003
    6,960
    144
    For the final voltage, and in the absence of a specific time, in the above equation use t = \infty, therefore you get:

    v(t) = 6*exp(-\infty)

    exp(-\infty) = 0, therefore in this ideal scenario the voltage across the resistor is 0V, i.e. the entire source voltage is across the capacitor.

    Dave
     
Loading...