Transcript Basics of Electricity

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
History
2500 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
Faucet
Pipe
Tank = Battery
Pipe = Wiring
Faucet = Switch
Current
Current: The flow of electric charge
Tank (Battery)
Faucet (Switch)
Pipe (Wiring)
When the faucet (switch) is off, is there any flow (current)?
NO
When the faucet (switch) is on, is there any flow (current)?
YES
Current in a Circuit
off
on
When the switch is off, there is no current.
When the switch is on, there is current.
Voltage
Voltage: The force (pressure) behind
the flow of current
Tank (Battery)
Faucet (Switch)
Pipe (Wiring)
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.
Voltage in a Circuit
off
on
The battery provides voltage that will push current
through the bulb when the switch is on.
Resistance
Resistance: The opposition to the
flow of current.
Tank (Battery)
Faucet (Switch)
Pipe (Wiring)
What happens to the flow (current) if a rock gets lodged in the pipe?
Flow (current) decreases.
Resistance in a Circuit
off
on
Resistors are components that limit the flow of electricity.
Reducing current causes the bulb to become more dim.
Types of Electricity
(You might already know these!)
Types of Electricity
Static Electricity
The electrical charge an object
develops as a result of having an
unequal number of protons and
electrons.
Current Electricity
The movement of electrons
through a conductor.
Static Electricity
• Uncontrollable
Electricity
• Lightening
• Static Cling
• Wool socks on a carpet
“shocks”
Current Electricity
Two Types:
Direct Current
(DC)
Alternating Current
(AC)
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