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!

Contradiction on kvl kcl laws question

  1. Jan 20, 2010 #1

    this is a part of the solution
    the is a voltage drop on capacitor C1 which makes current shock on C1
    and a current shock on R2 and R3
    and it makes a KVL contradiction on the right branch and the outer branch.

    and thats why the continuety laws holds"

    what is current shock?
    why its also on R2 and R3?
    why KVL laws contradict?
    why there is continuety ?
  2. jcsd
  3. Jan 20, 2010 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Not sure what a current shock is or what contradiction they're referring to, but what they probably mean is this:

    In a DC circuit, once any transients have died out, the capacitors are essentially open circuits, so no current is flowing anywhere in the circuit. If there's no current, there's no voltage drop across the resistors, so the 12-volt drop for each loop must occur across the capacitors.

    At t=0, the switch is closed, causing the voltage of the point between R2 and R3 to discontinuously jump to 6 volts (relative to the bottom line of the circuit). For a capacitor, the current flowing through it may be discontinuous, but the voltage across it must be continuous. This means that t=0+, the capacitors still have a 12-volt drop across them; therefore, both resistors now have a 6-volt drop across them. The current therefore jumps discontinuously from 0 A to 1.5 A when the switch is closed.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook