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 Lots of negative charge (high PE) Lots of positive charge (low PE) Electrons flow from high PE (negative terminal) to low PE (positive terminal)

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 Temperature Length Thickness

The Sink Model  Voltage  the pressure of that particular sink More pressure = more flow More pressure = more flow Cabin shower vs. home shower Cabin shower vs. home shower  Current  the actual flow of water  Resistance  the handle of the sink Less resistance = more “flow” Less resistance = more “flow” More resistance = less “flow” More resistance = less “flow”

Circuit Light bulbs not lit, because there is no longer a complete circuit Circuit: A complete path for electrons to flow

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 vs. Direct Current AC DC AC DCAC DCAC DC AC – When the direction of electron movement regularly changes DC – Electrons move continuously from the negative terminal to the positive terminal