# Homework Help: Resistive Network - Help please

1. Nov 4, 2014

### VisualStudio

1. The problem statement, all variables and given/known data

In the above diagram, calculate the total resistance between A and C

R1 = R2 = R3 = R5 = 3.3 Ω

R4 = R7 = R8 = 6.6 Ω

R6 = R9 = R10 = 2.4 Ω

2. Relevant equations
Sum/Product
3. The attempt at a solution
Can anyone give me an insight on where to start for this?
So my current guess is that, R8+R10 = Parallel, meaning that then becomes in series with R9, I really don't know where to start with this

2. Nov 4, 2014

### Staff: Mentor

Welcome to the PF.

I don't see a lot of simplifications in the circuit. Just write the KCL equations and solve. Put a 1V source between A and C, and see how much current you get. :-)

3. Nov 4, 2014

### VisualStudio

Hi, the question is to calculate the total resistance, therefore we don't need to put in a correct source, correct?

4. Nov 4, 2014

### Staff: Mentor

But that network is complicated enough that I don't see easy ways to use series & parallel combinations to collapse the network down to a resistor between A & C. Instead, just put an imaginary 1V voltage source between A & C, and calculate the node voltages and currents. That is one way to figure out the equivalent resistance.

5. Nov 4, 2014

### vela

Staff Emeritus
R8 and R10 aren't in parallel. R9 and R10 are, but their combination isn't in series with anything else. There are two other pairs in parallel as well. Note also that R1 is shorted.

If you know the delta-wye transformation, you could use that, but Berkeman's suggestion is probably easiest once you simplify the circuit as much as you can.

6. Nov 6, 2014

### VisualStudio

Ok thanks for your help, i'll be having another crack at it tommorrow. So what is exactly in series and parallel please?

7. Nov 6, 2014

### vela

Staff Emeritus
When two elements are In series, the current that goes through one must go through the other.

When two elements are in parallel, they're connected to the same two nodes, so the voltage across them is identical.

8. Nov 6, 2014

### VisualStudio

So do you think it's wise that I add a voltage source to this circuit? And where would i place it?

9. Nov 6, 2014

### vela

Staff Emeritus
If you can't simplify it down to one resistor, then yes, you need to add a source. You're trying to find the resistance between A and C, right? Where do you think you should place the source?

10. Nov 8, 2014

### VisualStudio

11. Nov 9, 2014

### VisualStudio

Could anyone help me with this?

12. Nov 9, 2014

### Staff: Mentor

First make all the parallel resistance simplifications that are available. Pay attention to what R1 is connected to.
Then identify an obvious candidate for Y to Delta transformation to generate more parallel resistor opportunities.

13. Nov 9, 2014

### Staff: Mentor

You can use series and parallel resistors until you get a network with 5 resistors where this does not work any more (plus one resistor that can be treated separately).
That smaller network will need a Delta/Y transformation or Kirchhoff's laws, but start with the easier steps first.