Originally Posted by **tommoturbo** I am struggling as usual with quite a confusing circuit i need to find i1 i2 and i3 in this circuit using kirchoffs laws
R1=.5 ohm R2=1 ohm R3=1ohm R4=.5ohm R5=1ohm
i know i need 3 loops
loop 1 is V1...ABCD....V1
loop 2 is V1...ACD.....V1
Loop 3 is V1....ABD....V1
i have worked out loop1 to be
I1R1-I3R5-(I2+I3)R4 = 1V
but the other loops look wrong and then i cant seem to use simultaneus equations effectively.
Any help much appreciated |

I've made some changes to your diagram. You only need three of the six currents on the diagram, but I suspect you'll have to find them anyway.

So, first let's talk about the junction rule.

At point A we have $\displaystyle I_0 = I_1 + I_2$

At point B we have $\displaystyle I_1 = I_3 + I_4$

At point C we have $\displaystyle I_2 + I_3 = I_5$

At point D we have $\displaystyle I_5 + I_4 = I_0$

Four equations in six unknowns. We need two more equations. Let's use your ABCD loop:

$\displaystyle -I_1R_1 - I_3R_5 - I_5R_4 + 1 = 0$

And let's pick the ABDC path:

$\displaystyle -I_1R_1 -I_4R_3 + I_5R_4+I_2R_2 = 0$

Give solving that system a try and see what you can come up with. If you need more help, simply ask.

-Dan