# Homework Help: Contradiction on kvl kcl laws question

1. Jan 20, 2010

### nhrock3

http://i49.tinypic.com/1yu634.jpg

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 there is continuety ?

2. Jan 20, 2010

### vela

Staff Emeritus
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.