Download Electric Current

Electric Current & Circuits
What is the difference between static
electricity and current electricity?
Static electricity is stationary or collects on the surface of
an object, whereas current electricity is flowing very
rapidly through a conductor.
The flow of electricity in current electricity has electrical
pressure or voltage. Electric charges flow from an area
of high voltage to an area of low voltage.
Water pressure
and voltage
behave in
similar ways.
Electric Current
Electrons flow from high PE (negative
terminal) to low PE (positive terminal)
Lots of negative
charge (high PE)
Lots of positive
charge (low PE)
Voltage (V)
Difference in PE causes pressure 
Voltage
A voltmeter is used to measure the voltage of
a component in a circuit
Voltage = Electrical Pressure
 You
may hear voltage also be referred to
as a potential difference
 Dam and water example
Current (I)
The flow of electrons  Current
The pressure of the water flowing through the
pipes on the last slide compare to the voltage
(electric potential) flowing through the wires of the
circuit. The unit used to measure voltage is volts
(V).
The flow of charges in a circuit is called current.
Current (I) is measured in Amperes (A).
Current is measured with a tool called an
Ammeter
Resistance (R)
The opposition to the flow
of an electric current,
causing the electrical
energy to be converted to
thermal energy or light.
Factors that affect wire resistance
Temperature
Length
Thickness
The Sink Model
 Voltage
 the pressure of that particular
sink


More pressure = more flow
Cabin shower vs. home shower
 the actual flow of water
 Resistance  the handle of the sink
 Current


Less resistance = more “flow”
More resistance = less “flow”
Circuit
Circuit: A complete path for electrons to flow
Light bulbs not lit, because there is no longer a
complete circuit
Symbols

Wire

Switch (open)

Battery

Light bulb
Symbols

Resistors

Ammeter

Voltmeter
Series Circuits
Only one path for the electrons
to flow through
Series Circuit
Chrismas Vacation
Parallel Circuits
More than one
path for the
electrons to follow
Parallel Circuits
Power Source
Alternating Current
AC
vs.
Direct Current
DC
AC – When the direction of electron movement regularly
changes
DC – Electrons move continuously from the negative terminal
to the positive terminal