Transcript Series and Parallel Circuits

Series and Parallel
Circuits
Series Circuits
 Only one current path
X-mas Lights
 When one light goes, the whole
string goes . .
 Series circuits need every part to
carry the current
Series Circuits
V = V1 + V 2 + V 3 + . . .
I = I1 = I2 = I3 = . . .
Req = R1 + R2 + R3 + . . . .
Calculate: The total Resistance, Current
through each resistor, and Potential Drop
across each resistor
5Ω
6Ω
2Ω
9V
8 Ω6Ω
Parallel Circuit
 More
than one
current path
 Unlike series
circuits, each
segment operates
independently.
Parallel Circuits
V
I
= V1 = V2 = V3 = . . .
= I1 + I2 + I3 + . . .
1
1 1
1
    ...
Req R1 R2 R3
• Calculate: Total
Resistance,
Potential Difference
across each resistor,
and the current
through each
resistor.
9V
Kirchhoff’s Laws
First Law – Conservation of Charge
(Junction Rule)
 The sum entering any current junction is
equal to the sum leaving.
What is the magnitude and
direction of the current in wire X?
1A
X
2A
5A
1A
2A
X
5A
Kirchhoff’s Laws
Second Law – Conservation of Energy
(Loop Rule)
 The sum of all the potential drops and
applied voltage around a complete circuit
is equal to zero.
VT  V1  V2  V3  ...
VT  V1  V2  V3  ... Vn  0