#### Series and Parallel Circuits

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Transcript Series and Parallel Circuits

Principles of Physics
A circuit with one resistor
When one electron leaves the
voltage supply another one enters
How fast this exchange occurs is
based on resistance
One electron pushes another and
so on
More than one resistor in a
single path
Each electron must go
through every resistor
Total resistance increases
with every resistor added in
series
R1
R2
Current flow depends on all
resistors
Current through each resistor
is the same
IT = I1 = I2 = …
A voltage exists across every device (voltage
supply, resistors, light bulbs, etc.)
As an electron goes through a resistor or
device it loses energy because it does work to
get through
How much energy lost per Coulomb (voltage)
depends on the resistance
R1
R2
Voltage gained by electrons
when leaving the voltage
supply equals the total
voltage lost before returning
Since voltage is lost through
all resistors
VT = V1 + V2 + …
R1
R2
To determine the current leaving
the voltage supply the total
resistance must be used
RT = R1 + R2 +…
10 Ω
12 V
14 Ω
Determine the total current in the
circuit
V = IR
12 V = I(24 Ω)
I = 0.5 A
RT = R 1 + R 2
= 10 Ω + 14 Ω
= 24 Ω
10 Ω
12 V
14 Ω
Determine the voltage in the 10 Ω
resistor
V = IR
V= 0.5 A(10 Ω)
V=5V
10 Ω
12 V
14 Ω
Determine the voltage in the 14 Ω
resistor
V = IR
V= 0.5 A(14 Ω)
V=7V
or
VT = V1 + V2
12 V = 5 V + V2
V2 = 7 V
A
5Ω
12 V
B
5Ω
5Ω
12 V
5Ω
5Ω
By adding another resistor in series
Increase total resistance
Decreases current
Voltage across each resistor decreases
Adding a resistor in series increases the total
resistance
When one resistor is disconnected the circuit is
open – current does not flow
Everyone has to go through all doors to get out
The smallest door slows the movement the most