00:01
This problem is a parallel circuit and it leans heavily on the notion, the understanding that the voltage drop across each branch in a parallel circuit is identical.
00:13
And in this problem, it is drawn off to the right -hand side as v -sub -s.
00:18
So i can use kirchhoff's current law, which says that the sum of the currents in any particular node is equal to zero.
00:29
So i can pick one of these nodes and say that the current in is equal to the current out.
00:35
So i'm just going to use the top node in the left.
00:40
So into that i have, coming in, i have two millimets.
00:48
And i'm going to say that that is negative.
00:51
So i have that coming in and that the current's coming out.
00:55
I have the one going straight down.
00:58
So i have v .s, that's the voltage across that branch, and the current is voltage divided by resistance, and i have 2 kilo -ooms.
01:09
Then in the next branch, i have v -sab -s, again, and that branch resistance is 1 -kilome.
01:18
Then at the end, i have a current supply that is coming into the node.
01:24
And so there, i have it minus, and that is minus 2 v .x, and that's over k...