Electric Current & CircuitsElectric 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 CurrentElectric Current
Lots of negative Lots of negative charge (high PE)charge (high PE) Lots of positive Lots of positive
charge (low PE)charge (low PE)
Electrons flow from high PE (negative Electrons flow from high PE (negative terminal) to low PE (positive terminal)terminal) to low PE (positive terminal)
Voltage (V)Voltage (V)
Difference in PE causes pressure Difference in PE causes pressure
VoltageVoltage
A voltmeter is used to measure the voltage of a component in a circuit
Voltage = Electrical Pressure Voltage = Electrical Pressure
You may hear voltage also be referred to You may hear voltage also be referred to as a potential differenceas a potential difference
Dam and water example Dam and water example
Current (I)Current (I)
The flow of electrons The flow of electrons Current 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)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 resistanceFactors that affect wire resistance TemperatureTemperature
LengthLength ThicknessThickness
The Sink ModelThe Sink Model
Voltage Voltage the pressure of that particular the pressure of that particular sinksink More pressure = more flowMore pressure = more flow Cabin shower vs. home shower Cabin shower vs. home shower
Current Current the actual flow of water the actual flow of water Resistance Resistance the handle of the sink the handle of the sink
Less resistance = more “flow”Less resistance = more “flow” More resistance = less “flow” More resistance = less “flow”
CircuitCircuit
Light bulbs not lit, because there is no longer a complete circuit
Circuit: A complete path for electrons to flow
SymbolsSymbols
WireWire
Switch (open)Switch (open)
BatteryBattery
Light bulbLight bulb
SymbolsSymbols
ResistorsResistors
AmmeterAmmeter
VoltmeterVoltmeter
Series CircuitsSeries Circuits
Only one path for the electrons Only one path for the electrons to flow throughto flow through
Series CircuitSeries Circuit
Chrismas Vacation
Parallel CircuitsParallel Circuits
More than one More than one path for the path for the electrons to followelectrons to follow
Parallel CircuitsParallel Circuits
Power SourcePower Source
Alternating Current vs. Direct CurrentAlternating Current vs. Direct Current
AC DCAC – When the direction of electron movement regularly changes
DC – Electrons move continuously from the negative terminal to the positive terminal
