Combination circuits

1. Mar 9, 2007

Aikenfan

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

2. Relevant equations
V = IR
P = IV

Please help....i dont exactly know where to start, we have never done any problems like this before but it showed up in my homework...i know those equations are relevant, but i dont know where to go from there. thank you very much
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Mar 9, 2007

Staff: Mentor

If you don't see an easy way to collapse a set of resistors using parallel and series combination rules (I don't see one offhand here), then just use the KCL to solve for the node voltages, and use that to figure out what the equivalent resistance is of the whole thing. Once you have all the node voltages, that gives you the component currents, and the overall resistance is just the overall voltage diveded by the total current in one end.

3. Mar 9, 2007

Aikenfan

sorry if this sounds stupid, but how do i solve for the node voltages? im a bit confused.

4. Mar 9, 2007

5. Mar 9, 2007

nrqed

What Berkeman said is true but in this particular problem, it is possible to combine the resistors using series and parallel combinations. This is the first approach to try since it is faster (but using Kirchhoff's laws would always work). Try to see if you can spot any two resistors that are in series or in parallel. Do you see that there is one? Then replace it by an equaivalent resistor. repeat again (look for a pair in series or in parallel) and so on. It;s possible to combine all those resistors into a single equivalent one.