1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Transient RC circuits.

  1. Dec 29, 2013 #1
    1. The problem statement, all variables and given/known data
    Determine the current flowing when the capacitor has been discharging for 5μs
    Capacitance=400 pico farads which is charged to 10v through a 50kΩ resistor.

    2. Relevant equations
    Vc = ve-t/CR

    3. The attempt at a solution So Vc =Ve -t/CR
    -t/CR = -5*10^-6/400*10^-12*50*10^3
    Which equals -0.25 so...
    Vc= 10*e-0.25
    Vc = 10*0.7788
    Vc = 7.788 volts after 5 micro seconds

    To find the current flowing after 5 micro seconds
    i = Vr/R since Vr=Vc Vc/R = 7.788/50000 = 0.156mA.
    Am i in the right ball park with this? Any guidance will be greatly appreciated.
  2. jcsd
  3. Dec 29, 2013 #2


    User Avatar

    Staff: Mentor

    Yup, looks fine.

    You could also have written the expression for the current ##I(t) = I_o e^{-\frac{t}{\tau}}## using the initial current Io from the initial conditions.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted