1. Complex Circuits Some of this, some of that…

2. Complex Circuits The main idea in finding total resistance is to make a complex circuit into a series circuit.

3. Complex Circuit A complex circuit is a circuit that has some parts like a series circuit and some parts like a parallel circuit. &

4. Complex Circuits Consider the following circuit: 8Ω2Ω8Ω2Ω 6Ω 1Ω 9V

5. Complex Circuits It looks a lot like a regular series circuit except for this part: 8Ω2Ω8Ω2Ω 6Ω 1Ω 9V

6. Complex Circuits This extra loop works like a parallel circuit stuck inside the series circuit. So we gotta get rid of it!! 8Ω2Ω8Ω2Ω 6Ω 1Ω 9V

7. Complex Circuits We get rid of it by using the equivalent resistance formula for parallel circuits: 8Ω2Ω8Ω2Ω 6Ω 1Ω 9V

8. Complex Circuits We get rid of it by using the equivalent resistance formula for parallel circuits: 8Ω2Ω8Ω2Ω 6Ω 1Ω 9V

9. Complex Circuits Now we replace the parallel part with it’s equivalent resistance. Now it’s just a regular series circuit. 1.6Ω 6Ω 1Ω 9V

10. Complex Circuits From here, just use the series circuit formulas to find V, I, and R. 1.6Ω 6Ω 1Ω 9V

11. Complex Circuits We can go backwards from here to each resistor. Consider the 1.6Ω resistor we ‘created’ to replace the parallel part of the circuit… 1.6Ω

12. Complex Circuits What are the Voltage and Current there? 1.6Ω

13. Complex Circuits Look at the original parallel loop. What is the current through each resistor? (Remember V=1.68 through the loop) 8Ω2Ω8Ω2Ω

14. Complex Circuits 8Ω2Ω8Ω2Ω 8Ω2Ω8Ω2Ω

15. 8Ω2Ω8Ω2Ω 8Ω2Ω8Ω2Ω