Kirchhoff's Laws and Simultaneous Equations: Solving a Confusing Circuit

[tommoturbo]

Homework Statement

I am struggling as usual with quite a confusing circuit i need to find i1 i2 and i3 in this circuit using kirchhoffs laws

i know i need 3 loops



loop 1 is V1...ABCD...V1

loop 2 is V1...ACD...V1

Loop 3 is V1...ABD...V1

Homework Equations

R1=.5 ohm R2=1 ohm R3=1ohm R4=.5ohm R5=1ohm

The Attempt at a Solution

i have worked out loop1 to be



I1R1-I3R5-(I2+I3)R4 = 1V



but the other loops look wrong and then i can't seem to use simultaneus equations effectively.



Any help much appreciated

 

[The Electrician]

I can't view your image until it's approved. If you'll upload it to a free image hosting site, and post the link here, I'll be able to view it sooner.

 

[tommoturbo]

Thanks for the quick reply

think this might work

http://www.freeimagehosting.net/uploads/b9e9a8e890.jpg

 

[The Electrician]

The currents you've shown are branch currents, not loop currents.

The circuit is an unbalanced wheatstone bridge. See:

http://en.wikipedia.org/wiki/Wheatstone_bridge

If you redraw it to look like a wheatstone bridger, it will be easier to draw distinct loop currents.

 

[tommoturbo]

Hi Electrician

Thats how i initially approached the question i sent my workings out to my tutor who told me to separate it into the three loops and then use simultaneus equations to find the unknowns,

when i did it initially whith the wheatsone bridge approach i got values of 1.5 1 and 05 for the various currents when i do the loops the values in teh equations are mostly .5's and 1s
and are difficult to multiply out

 

[The Electrician]

Post a new image with the circuit drawn as a wheatstone bridge with 3 loop currents indicated. Show the equations you derived for each loop. Then I can help you.

 

[tommoturbo]

ok will do!


thanks Ian