# Homework Help: Mesh Current circuit calculations with matricies

1. Mar 14, 2012

### thehippyseal

1. The problem statement, all variables and given/known data
Using matrix algebra calculate the voltage expected across each resister in the circuit diagram.

Only need the simultaneous equations.

3. The attempt at a solution
-15=6800(I_b-I_a )+2200(I_b-I_c)
15=2200(I_c-I_b )+8200(I_c-I_d)
-25=8200(I_d-I_c )+4700I_d

Thanks for any help.

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2. Mar 14, 2012

### Staff: Mentor

Hi thehippyseal, Welcome to PF.

It looks like you're doing okay finding the mesh equations. You haven't written one for the first mesh (Ia) yet.

Once you have equations for all four loops, for each equation collect the terms for each current so you've got the form: a*Ia + b*Ib + c*Ic + d*Id = V. It should be straightforward to go to the matrix form from there.

3. Mar 14, 2012

### thehippyseal

Thanks for the reply. I seem to have got it right then.

With Ia I have
20=3300I_a+6800(I_a-I_c)
-15=6800(I_b-I_a )+2200(I_b-I_c)
15=2200(I_c-I_b )+8200(I_c-I_d)
-25=8200(I_d-I_c )+4700I_d

Cheers.