Download Electricity 2


Current: A flow of electrons, or individual
negative charges.
Copyright © 2010 Ryan P. Murphy
• The electrons have a mass (however
small), and when they move through the
conductor, there are collisions that
produce heat.
Copyright © 2010 Ryan P. Murphy
• Don’t over connect outlets because they
could short circuit.
Copyright © 2010 Ryan P. Murphy

Conductors, Insulators, Semi-conductors:
How easily energy is transferred through
the object by the moving charge.
Copyright © 2010 Ryan P. Murphy

Conductor – Electrons flow easily, semi
flows in the middle.
Copyright © 2010 Ryan P. Murphy

Semi-conductor: Conductivity between
conductor and insulator (electronics use).
Copyright © 2010 Ryan P. Murphy

Insulator – Electrons do not flow easily.
Copyright © 2010 Ryan P. Murphy

There are two main kinds of electric
current, direct current (DC) and
alternating current (AC).
Copyright © 2010 Ryan P. Murphy

There are two main kinds of electric
current, direct current (DC) and
alternating current (AC).
Any Guesses
about this
picture?
Copyright © 2010 Ryan P. Murphy

There are two main kinds of electric
current, direct current (DC) and
alternating current (AC).
Copyright © 2010 Ryan P. Murphy

(DC) Direct current is a flow of charge
always in one direction. (Batteries)
Copyright © 2010 Ryan P. Murphy

(AC) -Alternating current is a flow of
charge back and forth, changing its
direction many times in one second.
(Plugs and outlets / household)
Copyright © 2010 Ryan P. Murphy
• Advantages of AC
– Voltage can be raised or lowered
– More efficient over long distances
Copyright © 2010 Ryan P. Murphy
• Advantages of AC
– Voltage can be raised or lowered.
– More efficient over long distances
Copyright © 2010 Ryan P. Murphy
• Advantages of AC
– Voltage can be raised or lowered.
– More efficient over long distances.
Copyright © 2010 Ryan P. Murphy
• Advantages of AC
– Voltage can be raised or lowered.
– More efficient over long distances.
Copyright © 2010 Ryan P. Murphy
Recommended Soundtrack for the next
Activity. – Thunderstruck - Play Now!
“DC”
“Its one way!”
“AC”
“It Alternates!”
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
• Is this (AC) Alternating Current, or (DC)
Direct Current?
All Done!
• Where do you find this strange device?
– What does it do?
• Where do you find this strange device?
– What does it do?
• An electric meter or energy meter is a
device that measures the amount of
electrical energy consumed by a
residence, business, or an electrically
powered device.

Watt: The amount of electricity consumed
per second.
Copyright © 2010 Ryan P. Murphy
• A Watt is calculated by multiplying volts
times amps. Most household electrical
usage is billed in kilowatt hours, or the
amount of hours times 1,000 watts.
Copyright © 2010 Ryan P. Murphy
• Question? We have a small computer server
with a sticker that shows 2.5 amps. Given a
normal 120 Volt, 60 hz power source and
the ampere reading from equipment
– How many watts does it require?:
• Question? We have a small computer
server with a sticker that shows 2.5
amps. Given a normal 120 Volt, 60 hz
power source and the ampere reading
from equipment
– How many watts does it require?:
– Watts = Volts x Amps
• Question? We have a small computer
server with a sticker that shows 2.5
amps. Given a normal 120 Volt, 60 hz
power source and the ampere reading
from equipment
– How many watts does it require?:
– Watts = Volts x Amps
– Watts = 120v x 2.5amps
• Question? We have a small computer
server with a sticker that shows 2.5
amps. Given a normal 120 Volt, 60 hz
power source and the ampere reading
from equipment
– How many watts does it require?:
– Watts = Volts x Amps
– Watts = 120v x 2.5amps = 300watts
“Oh No!”
• Question? We have an electronic device
with a sticker that shows 5 amps. Given a
12 Volt battery power source, How many
watts does it require?:
• Question? We have an electronic device
with a sticker that shows 5 amps. Given a
12 Volt battery power source, How many
watts does it require?:
– Watts = Volts x Amps
• Question? We have an electronic device
with a sticker that shows 5 amps. Given a
12 Volt battery power source, How many
watts does it require?:
– Watts = Volts x Amps
– Watts = 12 volts x 5 amps =
• Question? We have an electronic device
with a sticker that shows 5 amps. Given a
12 Volt battery power source, How many
watts does it require?:
– Watts = Volts x Amps
– Watts = 12 volts x 5 amps = 60watts
“Oh No!”
“He’s dead, let’s
just leave
him.”

Ampere: A measure of how much current
moves through a wire in one second.
Basically, the larger the size of wire, the
greater the ampere capacity.
Copyright © 2010 Ryan P. Murphy
• Where do your see these plugs?
– Why are they larger?
Copyright © 2010 Ryan P. Murphy
• Answer: The Plug to a dryer or stove is
much thicker than a standard outlet to
account for extra amps.
Copyright © 2010 Ryan P. Murphy
• Answer: The Plug to a dryer or stove is
much thicker than a standard outlet to
account for extra amps.
Copyright © 2010 Ryan P. Murphy

Resistance: Anything in an electrical circuit
that impedes the flow of current is
referred to as resistance.
Copyright © 2010 Ryan P. Murphy