1. Parallel Circuits

2. I _ + VR R I1I1 I2I2 I

3. Parallel Circuit Rules A parallel circuit has two or more paths for current to flow through. Voltage is the same across each component of the parallel circuit. V S = V 1 = V 2 = V 3 … V S = V 1 = V 2 = V 3 …

4. Parallel Circuit Rules The sum of the currents through each path is equal to the total current that flows from the source. I T = I 1 + I 2 + I 3 …

5. Let’s find the total Resistance I T = I 1 + I 2 + I 3 … Use V and R to find I: V T V 1 V 2 V 3 R T R 1 R 2 R 3 R T R 1 R 2 R 3 =++

6. V T V 1 V 2 V 3 R T R 1 R 2 R 3 R T R 1 R 2 R 3 =++ Use: V S = V 1 = V 2 = V 3 Use: V S = V 1 = V 2 = V 3 1 1 1 1 1 1 1 1 R T R 1 R 2 R 3 R T R 1 R 2 R 3 =++

7. Parallel Circuit Rules The Total Resistance of a Parallel Circuit is always less than the smallest resistor.

8. Example ITIT ITIT _ + VR1R1 R2R2 I1I1 I2I2 R3R3 I3I3

9. Given: V = 36V R 1 = 6 Ω R 2 = 9 Ω R 3 = 18 Ω Find: R T = ? I 1 = ? I 2 = ? I 3 = ?

10. Example ITIT ITIT _ + VR1R1 R2R2 I1I1 I2I2 R3R3 I3I3

11. Given: V = 120V R 1 = 30k Ω R 2 = 30k Ω R 3 = 30k Ω Find: R T = ? I 1 = ? I 2 = ? I 3 = ?

12. Comp 1 2 3 Total RkΩRkΩ I mAV P mW 30 10120 4 4 4 12 480 1440

13. Example ITIT ITIT _ + VR1R1 R2R2 I1I1 I2I2 R3R3 I3I3

14. Given: R 1 = 6Ω I T = 10mA I 2 = 3mA I 3 = 2mA Find: R T = ? V T = ? I I = ? R 2 = ? R 3 = ?

15. Comp 1 2 3 Total RkΩRkΩ I mAV P mW 6 10 15 3 30 5 3 2 10 150 90 60 300