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Basics of Electricity
What is Electricity?
• Involves the movement of electrons• Is invisible• Provides light, heat, sound, motion . . .• Has been practical for use over the last 100 years
History2500 years ago, the Greeks rubbed amber with other materials.
They discovered that this process would attract feathers and other lightweight materials to the amber.
History
Ben Franklin suggested that . . .
. . .opposite charges attract
and like charges repel.
+ -
History
Ben Franklin suggested that . . .
. . .opposite charges attract
and like charges repel.
+ +
The Law of Charges explains why the electrons continue to be bonded to the nucleus.
Electron Flow
An electron from one atom can knock out an electron from another atom.
Electron Flow
Electricity is created as electrons collide and transfer from atom to atom.
Play Animation
What Makes Up Electricity?
Let’s compare it to something we know --- Water!
Water Analogy
Tank = Battery
Pipe = Wiring
Faucet = Switch
Tank Faucet
Pipe
Current
Current: The flow of electric charge
When the faucet (switch) is off, is there any flow (current)?
NO
When the faucet (switch) is on, is there any flow (current)?
YES
Tank (Battery) Faucet (Switch)
Pipe (Wiring)
Current in a Circuit
When the switch is off, there is no current.
When the switch is on, there is current.
off onoff on
Voltage
Voltage: The force (pressure) behind the flow of current
When the faucet (switch) is off, is there any pressure (voltage)?
YES – Pressure (voltage) is pushing against the pipe, tank, and the faucet.
When the faucet (switch) is on, is there any pressure (voltage)?
YES – Pressure (voltage) pushes flow (current) through the system.
Tank (Battery) Faucet (Switch)
Pipe (Wiring)
Voltage in a Circuit
The battery provides voltage that will push current through the bulb when the switch is on.
off onoff on
Resistance
Resistance: The opposition to the flow of current.
What happens to the flow (current) if a rock gets lodged in the pipe?
Flow (current) decreases.
Tank (Battery) Faucet (Switch)
Pipe (Wiring)
Resistance in a Circuit
Resistors are components that limit the flow of electricity.
Reducing current causes the bulb to become more dim.
off on
Resistor
Types of Electricity
(You might already know these!)
Types of Electricity
Static ElectricityThe electrical charge an object develops as a result of having an unequal number of protons and electrons.
Current ElectricityThe movement of electrons through a conductor.
Static Electricity
• Uncontrollable Electricity
• Lightening• Static Cling• Wool socks on a carpet
“shocks”
Current Electricity
Two Types:
Alternating Current (AC)
Direct Current (DC)
Direct Current
The electrons flow in the same direction all the time, from negative to positive.
- +
Direct Current
Comes from• Batteries• Converted from Alternating Current
Used for electronic devices including• Computers• iPods• Cell phones• Anything that has a “charger”
Alternating Current
The electrical current (movement of electrons) changes direction.
Alternating Current
Comes from Generators• Coal burning and nuclear power plants• Hydroelectric power plants• Wind and solar generators
Used for• Motors• Heaters• Lights• Anything that plugs into the wall
Image Resources
Microsoft, Inc. (2008). Clip Art. Retrieved September 10, 2008, from http://office.microsoft.com/en-us/clipart/default.aspx