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INTRODUCTION TO
ENERGY, POWER, AND
ELECTRICITY
© Daniel L. Wilson, Dr. Michael
A. De Miranda, Dr. Thomas J.
Siller, & Dr. Todd D. Fantz
School House Rock Introduction Video
Goals
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
By the end of this lesson you will be able to:
 Explain
the basic concepts of energy vs. power.
 Relate the three fundamental properties of a circuit
(voltage, current, and resistance) to the flow of water.
 Solve Ohm’s Law for simple circuits.
 Discuss the relationships between electricity and
magnetism and how these relate to modern powergeneration techniques.
 Build, test, improve, and explain the functionality of
simple electromagnets and motors.
Let’s Come Clean
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
What do you know about energy?
Where does the energy we use come from?
Why is there so much talk about clean energy?
Today
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


What is energy?
What is power?
What is electricity?
 Current,
voltage, resistance, and power
 What are the relationships between these parameters?
Energy
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So, everyone keeps talking about clean energy.
Image 1
From: The Breakthrough Institute, CA
URL:
http://thebreakthrough.org/blog/2007/08/in_love_wit
h_the_sun.shtml
What is energy, anyways?
Energy
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
Energy, simply put, is the ability to do work
 Energy
must be controlled to do work effectively
 Energy is most commonly measured in joules, calories,
British thermal unit (Btu), and kWh
 Kinetic, potential, thermal, chemical, electrical, nuclear
Image 2
From: Crunch Gear
URL:
http://www.crunchgear.com/2009/04/0
3/ibm-could-buy-sun/
Image 3
From: American Feast's Sustainable Food Blog
URL:
http://blog.americanfeast.com/2009/08/missour
i_wind_farm_draws_visit.html
Image 4
From: HubPages, Inc.
URL:
http://hubpages.com/hub/MonsterEnergy-Drink
Power vs. Energy
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
Power, like energy, is a measure of ability to do
work, but it depends on time.
 Power
is how much energy we can deliver in a certain
amount of time
 Units include horsepower, watts, foot-pounds per minute
Image 5
From: Parents
URL: http://www.parents.com/kids/education/reading/playdatewith-a-purpose-downloads/
Image 6
From: Dream Road
URL: http://www.dreamroad.us/bugatti-veyron-fastest-car-in-theworld/
Power vs. Energy
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Which uses more power during its formation: a volcano or a mountain?
Image 7
From: Do Something.org
URL: http://www.dosomething.org/tipsandtools/11-facts-about-volcanoes
Thrust SSC
Image 8
From: Top Wallpapers
URL: http://www.jamwallpapers.com/wpcontent/uploads/2010/09/Rocky-Mountains-3.jpg
Shuttle Transporter
Power
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
Power is simply Energy/Time
P = E/t
How can we increase power?
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Electrical Energy and Power
If it weren't for electricity we'd all be watching
television by candlelight.
-George Gobal
What is Electricity?
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
Atoms are made up of three primary components
 Protons
 Neutrons
 Electrons
Figure 9
From: Cambridge Physics Outlet, MA
URL: http://www.vtaide.com/png/atom.htm

When electrons move from atom to atom, we call
that electricity
What are electricity’s characteristics?
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
Voltage


Current


The quantity of electrons that pass through a wire or
other conductor in one second. You can also think
about it like the width and depth of a river.
Resistance


The amount of “pressure” behind the electrons
forcing them to move from atom to atom. You can
also think about it like the steepness of a river.
How hard it is for the electrons to move through
something. You can also think about it like the
number of rocks and trees and other debris slowing
down a river.
Power

The ability of the electricity to do a certain amount
of work in a certain time (voltage x current). You
can also think about this like the overall “power” or
a river (how steep it is x how much water is running
in it).
Important Equations
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
Ohm’s Law, Georg Ohm, 1827
V=I*R

Power Equation
P=V*I
Practice Ohm’s Law
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
Draw the following in the blank space provided on
your worksheet:
5 volt
battery
10 ohm resistor
Diagram 1

What is the current through this wire?
0.5 amps
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Electromagnetism
Magnetics
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Image 9
From: Paisley + Patterns
URL: http://paisley-and-patterns.blogspot.com/2011/03/magnetic-field-pattern-what-in-world-is.html
Magnetics
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
Activity
 Try
to visualize magnetic fields using your neodynium
magnets and a plastic lid
 Be
careful, the magnets can crack and hurt you!
 Be careful not to spill iron filings everywhere
What do you notice? Does the field shape change depending
on how you orient your magnet?
Cool magnet video
Electromagnetics
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Electricity and magnetism are inextricably linked.
Whenever you see electricity, magnetism is hiding
somewhere in the shadows. Whenever you see
magnetism, electricity is also hiding somewhere.
Electromagnetics
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
A long straight wire with current running through it
will create a loops of magnetic field around it
Image 10
Figure 2
From: the full wiki
URL: http://maps.thefullwiki.org/Magnetic_field
Solenoids and Electromagnets
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
If we stack or loop a bunch of wire, we can magnify and straighten out a
magnetic field. This is called a solenoid or electromagnet
B=(N*I)/L
Figure 3
From: TutorVista.com
URL: http://www.tutorvista.com/physics/electromagnetsolenoid
Where N is the number of turns, I is the current, and L is the length of the coil

Let’s make our own electromagnets!
Solenoids and Electromagnets
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

What happened?
Did more coils always mean a stronger magnet?
One part of engineering is a process of trade-offs
called optimization
B=N*I/L
B=N*V/(L*R2)
B=N*V/(L*l2r2)
B=N*V*d2/(L*l*k2)
To be effective engineers, we always have to ask questions about why we
are seeing the things we do.
Motors
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
To create a motor, we take advantage of the fact
that a current-carrying wire in a magnetic field will
feel a force
 The
force the wire feels is always in the direction that is
perpendicular to both the current and the magnetic
field
(a)
Figure 4
From: A technical guide to building fighting robots
URL: http://homepages.which.net/~paul.hills/Motors/Motors.html
(b)
Homopolar Motor
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
The homopolar motor motor works by placing a
short section of wire perpendicular to the magnetic
field wrapping around the neodymium magnets.
current
Magnetic
field
(a)
(b)
(c)
Figure 5
From: Wikipedia
URL: http://upload.wikimedia.org/wikipedia/commons/3/32/Motor_homopolar_flux_force.png
Homopolar Motor
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

You Try!
Try to figure out a way to make a nail spin instead
of a wire 
©Michael A. de Miranda, Daniel L. Wilson, Thomas J. Siller, & Todd D. Fantz