1. Parallel vs. Series Circuit

2. Series Circuit Only a single pathway
As more bulbs are added in series, the voltage in the circuit decreases.
Current remains the same.
If any bulb is removed then the circuit will not work

3. Parallel Circuit More than one path along which electrons can flow
As more bulbs are added, voltage remains the same
Current is split between pathways
If a bulb is removed, it will not affect the bulbs on separate paths

4. Cells in Series
Connect dry cells end to end, positive to negative terminal
Voltage from each cell is combined /added together
E.g. 1.5V + 1.5V+1.5V= 4.5V

5. The water analogy
2 pumps are put together to lift water higher; more gravitational potential energy, more voltage

6. CELLS IN SERIES =
MORE Voltage

7. Parallel Cells Dry cells are connected side by side
Positive terminal connected to positive and negative to negative
Overall voltage remains the same, but lasts longer
Amount of electrons available is multiplied

8. Cells in parallel =
Longer Lasting

9. Current Through Loads in Series
Current stays the same series.
Isource=I1=I2=I3
The actual amount of current is inversely related to the amount of resistance and can be found using Ohm's law (ΔV = I • R),

10. Voltage through loads in series
Voltage is shared between loads in series
Vload= Vsource/#of loads
For identical loads
Vsource= V1+V2+V3

11. Resistance increases as you add loads in series Req=R1+R2+R3
Resistance in Series
Resistance increases as you add loads in series Req=R1+R2+R3

12. Analogy: Series Current= car ; voltage= people house = load1 3 2

13. Finding Voltage VT= V1 + V2 V1= VT- V2 VT= V1 + V2+ V3 V2= VT- V1-V3=
= 40V
VT= V1 + V2+ V3
V2= VT- V1-V3 =
= 5 V

14. Current through Loads in Parallel
Current is shared between different loads in parallel
Isource= I1+I2+I3
The sum of currents must equal the current entering at the connecting point

15. Voltage through Loads in Parallel
Voltage remains the same throughout a parallel circuit
Vsource= V1=V2=V3
* Bulbs in parallel were all bright

16. Analogy: Parallel Current= car ; voltage= people house = load

17. Resistance in parallel
Resistance decreases as you move from series to parallel 1 𝑅𝑒𝑞 = 1 𝑅1 + 1 𝑅2 + 1 𝑅3 *think lines in an amusement park

18. Quiz #1 1. Find the total resistance equivalence
a. Two 3-Ω resistors placed in series
b. Three 3-Ω resistors placed in series
c. Three 5-Ω resistors placed in parallel
d. Three resistors with resistance values of 2-Ω , 4-Ω , and 6-Ω are placed in series.
e. Three resistors with resistance values of 5-Ω , 6-Ω , and 7-Ω are placed in series.
f. Three resistors with resistance values of 12-Ω, 3-Ω, and 21-Ω are placed in parallel.

19. A. Req= R1 + R2 = 6Ω
B. Req= R1 + R2 + R3 = 9Ω
C. 1 𝑅𝑒𝑞 = 1 𝑅 𝑅2 + 1 𝑅3
1 𝑅𝑒𝑞 = 3/5
Req= 5/3= 1.7Ω
D. 12Ω
E. 18Ω
F. Req= 28/13= 2.15 Ω