# Homework Help: Kirchhoff's current law and nodal analysis

1. Oct 12, 2011

### jonmondalson

Hello,

I'm looking to work out the current at I in the following circuit using Kirchoff's current law and nodal analysis:
[PLAIN]http://img853.imageshack.us/img853/4792/circuitgem.jpg [Broken]

Using Kirchoff's voltage law (and loop analysis), I got a current of (35/22)A, but for the current law method I'm having problems.

I obtained the following equations using Kirchoff's current law:
4i1+2i2+4i3=5
-4i3-2i4=-10
and nodal analysis:
-i2+i3-i4=0
i1+i4=I

But solving these 4 equations produces a value for I of 0, which doesn't make sense, let alone agree with the answer using the other method.

Any help will be greatly appreciated.
Thank you

Last edited by a moderator: May 5, 2017
2. Oct 12, 2011

### phinds

I got as far as your first equation and have no idea how you got it. (Actually, I think I know, but it's nonsensical)

Try drawing the I's and V's out on the diagram and writing equations that make sense.

It's a VERY straightforward problem.