Download Series & Parallel Circuits

Series & Parallel Circuits
Chapter 23
23.1 Simple Circuits
• Water moving down a mountain river
• The water goes down the mountain
because of a difference in gravitational
potential energy
• The water represents electrical current
• The electric current moves through a
circuit because of a difference in
electric potential
Series Circuits
• A circuit that has only one path for the
current to flow
• Remember that charge cannot be created
or destroyed and current is amount
charge moving per second
• The potential difference is shared by each
device in the circuit.
• Also call voltage drop because as the
current passes through each device uses
some of the total voltage until it is all
used up
I & R in a series circuit
• In an electric circuit, the increase in
voltage provided by the energy source
(battery), Vsource, is equal to the sum of
the voltage drop across the devices
• Vsource=VA+VB+…
Equivalent Resistance in a Series Circuit
• The equivalent resistance is the one
resistor that could replace all the
resistors of the circuit and keep the
same current
• In a series circuit the resistance adds
• R=RA+RB+…
• The equivalent resistance is greater
than any individual resistor
Voltage drop in a Series Circuit
• As current moves through any circuit
the net change in potential must equal
zero
• Gains in the energy source and loses
as current passes through the resistors
Voltage Divider
• Used to change a higher voltage to a
lower voltage as the current passes
through a device.
• Source is 12 V and device required 9 V
• A resistor is placed in series with the
device to use the extra 3 V
Parallel Circuits
• More than one path for the current to
flow
• Similar to a mountain river and breaks
off into three different rivers.
• All three have the same starting and
ending gravitational potential energy
• The total river current has to be split
into three separate paths
Resistors in a Parallel Circuit
•V=VA=VB…
…
•I=IA+IB+
V V
V



R RA RB
1
1
1



R RA RB
Equivalent
resistance for a
parallel circuit