1. EGR 1011 Chapter 6 Series-Parallel Circuits

2. EGR 1012 Examples of Series-Parallel Circuits

3. EGR 1013 Basic Configurations

4. EGR 1014 An Example for Analysis: Series Circuits Connected in Parallel

5. EGR 1015 Team Activity: Problem 1 on p. 173 – Method 1 Use the voltage divider method to calculate the voltages across R 1 & R 2. Use the voltage divider method to calculate the voltages across R 3 & R 4. Calculate the current through R 1 & R 2. Calculate the current through R 3 & R 4. Calculate the total current I T.

6. EGR 1016 Team Activity: Problem 1 on p. 173 – Method 2 Find the equivalent resistances R 12 & R 34. Find the total resistance R T. Find the total current I T.

7. EGR 1017 A Second Example: Parallel Circuits Connected in Series

8. EGR 1018 Team Activity: Problem 5 on p. 174. Find the equivalent resistances R 12 & R 34. Calculate the total current I T.

9. EGR 1019 Wheatstone Bridge Galvanometer – a sensitive ammeter

10. EGR 10110 Bridge Operation – based on three possible states: V A = V B V A > V B V A < V B

11. EGR 10111 Wheatstone Bridge: A series-parallel arrangement at “balance” Resistors R 1 and R 2 are in series –R 12 = R 1 + R 2 Resistors R 3 and R 4 are in series –R 34 = R 3 + R 4 Equivalent resistance R 12 is in parallel with equivalent resistance R 34

12. EGR 10112 Circuit Analysis at “balance”, galvanometer current =0

13. EGR 10113 Application of a Wheatstone Bridge: Smoke Detector Photoconductive Cells – Light-Controlled Resistors Used as Sensor and Reference When the amount of light striking the device increases, the resistance decreases (and vice-versa).

14. EGR 10114 Detector Diagram

15. EGR 10115 How it works When the air is clear, the bridge is balanced. If smoke enters the lower chamber via the vents, the resistance of the lower photoconductive cell increases, causing the bridge to become unbalanced, triggering the alarm. SMOKE