1. Series and Parallel Circuits
Ingrid Munson & Meghan Campbell
Series and Parallel Circuits

2. Circuits
Can either be series or parallel.

3. Series If you add a resistor (like another light):
Total resistance goes UP since all the current has must go through each resistor.

4. Adding Resistors to Series:
Current in the circuit will go DOWN (lights will dim)
If you remove a light bulb or one burns out—all go out!

5. Current in Series Current is the same at all points
Use Ohm’s Law to find current using resistance and voltage

6. Resistance in Series Add up all resistors to get total
Total resistance will go up because all of the current must go through each resistor.

7. Series Circuit
Closed electrical circuit that is connected so that the current passes through each circuit element in turn without branching off.

8. Race Track

9. Parallel Circuits
Have more than one path that the circuit can follow and electrical energy therefore is not shared.
Each electrical device can be on or off within the circuit.

10. Parallel Circuits
Cars have many pathways to travel, one might be a five lane freeway, while another is a two lane street. Eventually all cars must return to the service station for more energy.

11. Parallel Circuits Has at least one point where current divides
More than one path for current to flow
Paths are also known as branches

12. Lights in Parallel

13. Parallel: Total resistance goes down
If you add a resistor:
Total resistance goes down
Total current goes up when you add another path

14. Removing a Light Bulb
If you remove a light bulb or one burns out, the others stay on because the circuit is still closed.

15. Current in Parallel
Current flows into a branching point, the same total current must flow out again
Current depends on resistance in each branch

16. Voltage in Parallel
Voltage is the same across each branch – because each branch is on the same wire

17. Resistance in Parallel
Calculate current in each branch based on resistance in each branch by using Ohm’s Law

18. Batteries in Series and Parallel:

19. In series—The voltage is increased.
Battery Explanation
In series—The voltage is increased.
In parallel—No change in voltage; these batteries will last longer!

20. Equations - Series
Rt=R1+R2+R3
it=i1=i2=i3
Et=E1+E2+E3

21. Equations - Parallel
Et=E1=E2=E3
it=i1+i2+i3
1/Rt=1/R1+1/R2+1/R3