Download Parallel and Series Circuit

Parallel vs.
Series Circuit
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
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
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
The water analogy
• 2 pumps are put together to lift
water higher; more gravitational
potential energy, more voltage
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
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),
Voltage through loads
in series
Voltage is shared between
loads in series
Vload= Vsource/#of loads
• For identical loads
• Vsource= V1+V2+V3
Resistance in Series
Resistance increases as
you add loads in series
Req=R1+R2+R3
Analogy: Series
Current= car ; voltage= people
house = load
0
1
3
2
Finding Voltage
VT= V1 + V2
V1= VT- V2
= 120- 80
= 40V
VT= V1 + V2+ V3
V2= VT- V1-V3
= 12- 3 -4
=5V
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
Voltage through Loads
in Parallel
Voltage remains the same
throughout a parallel circuit
Vsource= V1=V2=V3
* Bulbs in parallel were all bright
Analogy: Parallel
Current= car ; voltage= people
house = load
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
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, 3Ω, and 21-Ω are placed in parallel.
• A. Req= R1 + R2 = 6Ω
• B. Req= R1 + R2 + R3 = 9Ω
• C.
1
𝑅𝑒𝑞
1
𝑅1
1
+
𝑅2
=
1
𝑅𝑒𝑞
= 3/5
1
+
𝑅3
Req= 5/3= 1.7Ω
D. 12Ω
• E. 18Ω
• F. Req= 28/13= 2.15 Ω