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Electricity Rocks!
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Electromagnetism
Engineering Teaching Kit
TABLE OF CONTENTS
TABLE OF CONTENTS………………………………………………………………………………………….1
TEACHING KIT OVERVIEW…………………………………………………………………………………2
UNIT OUTLINE……………………………………………………………………………………………………..4
MATERIALS LIST…………………………………………………………………………………………………..5
TEACHING PREP MATERIAL………………………………………………………………………..6 – 17
> DAY 1 BRIEFING…………………………………………………………………………………..…6
> DAY 2 BRIEFING……………………………………………………………………………………..8
> DAY 3 BRIEFING…………………………………………………………………………………...12
> DAY 4 BRIEFING……………………………………………………………………………………16
> DAY 5 BRIEFING……………………………………………………………………………………17
PICTURE CREDITS, REFERENCES.…………………………………………………………………….18
STUDENT PACKET…….………………………………………………………………………………..19 – 34
> DAY 1…………………………………………………….………………………………………..20 – 22
– “What is Engineering?”.......................................……………………………….20
– “Historically Speaking”........................................……………………………….21
– “Sounds Great!”.......................................………………………………………….22
> DAY 2………………………………………………………..…………………………………….23 – 26
– “It’s Electric!”........................................…………………………......................23
– “Got Magnetism?”........................................………………………………………25
– “Electromagnetic Induction”......................………………………………………26
> DAY 3………………………………………………………………………………………………27 – 30
– “Building a Speaker”.......................................…………………………………..27
– “Building Worksheet”........................................………………………………..29
– “Results Table”.......................................……………………………………………30
> DAY 4 – “Design, Test, Repeat…”......................................……………………………32
> DAY 5 – “Evaluation Survey”.......................................………………………….34 – 35
1
TEACHING KIT OVERVIEW
Grade Levels: 6, 7, 8
Subjects:


Science/Physics
Engineering/Technology
Duration: five 50-minute sessions
Description: In this lesson, students learn about the connection between science and
engineering. They explore the technological applications of electricity, magnetism,
and sound. Students are given an engineering design challenge, in which they must
design, build, test, and optimize a simple electro-mechanical speaker.
Engineering Connection:

Students learn principles of electricity, magnetism, and sound, and use this
knowledge to design, build, test, and optimize speakers.
Educational Standards:

Virginia Standards of Learning (SOL):

PS.8 (Physical Science) The student will investigate and understand
characteristics of sound and technological applications of sound waves.

6.2 (Grade 6) The student will investigate and understand basic sources of
energy, their origins, transformations, and uses. Key concept is energy
transformation.

6.4 (Grade 6) The student will investigate and understand basic characteristics
of electricity. Key concepts include
i. Electrical energy can be produced from a variety of energy sources
and can be transformed into…other form[s] of energy
ii. Electricity is related to magnetism
iii. Currents are either alternating or direct

PH.8 (Physics) The student will investigate and understand that energy can be
transferred and transformed to provide usable work. Key concepts include:
i. Transformation of energy among forms including mechanical…[and]
electrical
ii. Efficiency of systems
2
UNIT OUTLINE
Day 1 – Engineering & Sound

Objective: To understand the principles of sound
1. Introduction to Engineering
a. What is engineering?
b. History of speakers
i. Examples of speakers
2. Sound
a. Pitch
b. Volume
c. Transmission through media
3. ACTIVITY 1: Observing different sound frequencies using a ruler
4. Worksheets: “What is Engineering?”, “Historically Speaking”, “Sounds Great!”
Day 2 – Electricity & Magnetism

Objective: To understand the principles of electricity, magnetism, and
electromagnetism
1. Electricity
a. Current
b. Voltage
c. Resistance
d. Power
2. DEMO1: Water pump illustrating current flow and resistance
3. Magnetism
a. Poles
b. Magnetic fields
4. DEMO 2: Magnetic force at work
5. Electromagnetic coils
a. Field strength as a function of number of turns
b. Right hand rule
6. ACTIVITY 2: Electromagnet (magnetized nail)
7. Worksheets: “It’s Electric!”, “Got Magnetism?”
Day 3 – Speaker Construction

Objective: To understand how a speaker works
1. DEMO 4: Standard (Ordinary) speaker and Paper Cup (Extraordinary) speaker
2. ACTIVITY 3: Variations of a basic speaker
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3. Worksheets: “Building a Speaker”, “Building Worksheet”, “Results Table”
4. Material selection
5. Instruct students to bring in materials for the following day
Day 4 – Design & Testing


Objective: To understand how engineers design and how to apply these principles
to the competition
Objective: To test initial speaker designs and present a final design
1. The Engineering Design Process (10 min)
2. Worksheet: “Design, Test, Repeat”
3. ACTIVITY 4: Open build (40 min)
Day 5 – Design Competition
1. ACTIVITY 5: Team Competition (30 min)
2. Class Discussion: Concept Review (10 min)
3. Evaluation Survey (5 – 10 min)
The “Electricity Rocks” Team:
Scott Simmons, Ben Jessup, Chiedo Ohanyerenwa,
Chris Hemp, Coles Jennings, Marija Cvijetic, Eddie Pan
4
Materials List
(All quantities are per group, unless otherwise noted)
Day 1

12” Plastic Ruler (1/student)
Day 2
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2” Galvanized Nail (1)
3” Galvanized Nail (1)
4” Galvanized Nail (1)
A few paper clips
Insulated Copper Wire, 22 AWG (approx. 3 ft.)
C Cell Battery (1)
Small strips of electrical tape (2)
Bar magnet (1)
Plastic sleeve (1)
30AWG enamel wire (approx. 10 ft.)
D-cell battery holder with switch (1)
D-cell battery (1)
Small piece of sandpaper (1)
One-way hand pump (1)
½” clear plastic tubing (approx. 4 ft.)
Bucket (1)
Plastic zip ties (around 10)
Day 3
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IPOD
Commercial (25 W) computer speakers
Ready-made speaker (Styrofoam cup, magnet, coil of wire)
Plastic cup (1)
Paper cup (1)
Small disk magnet (1)
Small donut magnet (1)
30AWG enamel wire (approx. 10 ft.)
Small piece of sandpaper (1)
Sound meter
Days 4 & 5

(Same as Day 3 plus students’ own materials)
5
DAY 1 Briefing
What is engineering?
Engineering is the application of science to solve human problems and meet human needs.
History of speakers
People have known about acoustics and mechanical amplification of sound since
ancient times. The first electromagnetic speakers were developed in the middle of the 19th
century in the United States with the development of the telephone. Antonio Meucci,
Alexander Graham Bell, and Elisha Gray, working separately, all produced their own
versions of the telephone, which included speakers to convert an electrical signal into
sound. The first conical paper diaphragm speaker was described in 1901 by John Stroh in
Britain. Speaker development continued from then until the present day, with variations
on the fundamental designs as well as refinements to improve sound quality.
Armature Speaker, circa 1882 (2)
Direct Radiator Speaker, circa 1961 (2)
Examples of speakers
 Stereo systems
 Car horn
 Telephone
 Computer speaker
 Megaphone
Sound Overview:
Sound is a longitudinal (compression) wave traveling through a medium (solid,
liquid, or gas) which is received by a human ear and interpreted by the brain.
Pitch: the highness or lowness of a sound, and is determined by the frequency and
wavelength of the sound wave.
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Volume: the loudness of a sound (measured in decibels, or dB), and is determined by
the amplitude of the sound wave.
Transmission through media: Sound requires a media in which to move. It is
transmitted by the molecules within the media displacing each other in sequence along
a given direction. Because of this, denser media produces better sound
transmission and sound cannot be travel in a total vacuum (like outer space)
<< Activity 1: RULER Tones >>
Goal: To demonstrate the relationship between the frequency and pitch of a sound wave
using a simple vibrating lever.
Materials (per student):
 12” Plastic Ruler (1)
Preparation: None
Instructions: This activity is a very simple means of showing the relationship between
frequency and pitch. Students take the ruler and clamp it against the edge of the table with
one hand, leaving part of it hanging over the edge of the table. Then students flick the
ruler with the other hand, causing it to vibrate and make a distinct sound. The pitch of this
sound can be altered by clamping the ruler at different points along its length, causing it to
vibrate at different frequencies.
Clamping the ruler closer to the end (left) will cause a slow vibration and lower
pitch. Clamping it towards the middle (right) will increase the frequency and produce a
higher pitch. Students can experiment and even make simple songs with this crude musical
instrument.
SAFETY NOTICE: An overzealous student could break a cheap ruler and possibly inflict
harm when it snaps. Emphasize that a gentle flick is all that’s needed to produce a tone.
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DAY 2 briefing
Electricity Overview:
CURRENT, I: a flow of electric charge, measured in amperes (or Amps, A).
VOLTAGE, V: the amount of potential energy per unit charge, measured in Volts (V),
sometimes referred to as “electrical pressure.”
RESISTANCE, R: the property of a material to restrict the flow of electric charge,
measured in ohms (Ω).
POWER, P: the rate of electrical energy transformation (into heat, light, or mechanical
action), measured in watts (W).
Magnetism
MAGNETIC POLE: the faces of a magnet (there are always two, North and South).
They have opposite polarity and at either location the magnetic effect is the strongest.
MAGNETIC FIELD: A magnetic force exerted by the magnet on the area around it.
We can draw field lines to show the direction of the magnetic field at any given point.
Magnetic field lines around a bar magnet ( 3)
ELECTROMAGNETISM: A wire carrying current (I) produces magnetic field (B),
aligned centripetally with the wire’s center according to what is known as the “right
hand rule” – where the thumb points in the direction of the current, and the fingers
curl around in the direction of the magnetic field lines. The reverse case also holds.
Electromagnetic Field (3)
The Right Hand Rule (4)
When wire carrying a current is looped into a coil, the magnetic field produced inside the
coil is magnified, such that it is proportional to the number of turns (loops) in the coil (i.e.
a coil with more turns produces a more powerful magnetic field relative to a coil with fewer
turns, all other factors being the same).
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<< Activity 2: MAKING AN Electromagnet >>
Goal: To demonstrate the fundamentals of electromagnetism through a simple battery
powered electromagnet.
Teacher Tools:
 Wire Strippers
Materials (per group):
•2” Galvanized Nail (1)
•3” Galvanized Nail (1)
•4” Galvanized Nail (1)
•A few paper clips
•Insulated Copper Wire,
22 AWG (approx. 3 ft.)
•C Cell Battery (1)
•Strips of electrical tape (2)
Preparation: Students should be divided into small teams of two or three, each team given
the materials listed above. A small amount of insulation should be removed from each end
of the wire strands, to allow for proper electrical connection to the batteries.
Instructions: Each group should construct a simple electromagnet (pictured below). The
wire is coiled around a galvanized nail, ensuring that the coils are kept tight and neat to
maximize the magnet’s strength. Enough wire should be left for leads to the battery. One
lead should be attached to the positive end of the battery and one to the negative using
electrical tape (although shock risk is very small for a C cell battery, the tape is a safety
precaution). The students should be able to demonstrate how current flowing through the
wire coils magnetizes the nail by picking up paper clips with the electromagnet.
Wire Coiled Around a Nail (5)
Have the students experiment with different nail sizes, number of coil windings,
and double or triple-wrapping the wire in a small area rather than over the length of the
nail. This should give insight into what creates the strongest magnetic field.
SAFETY NOTICE: Although shock risk is minimal, the wire can heat up after some time
if the magnet is not disconnected. Make sure students do not leave an electromagnet
connected for more than 5 minutes at a time.
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<< Demonstration 1: Water Pump >>
Goal: To illustrate the basic concepts of voltage, current, and resistance, and Ohm’s law
through analogy to the flow of water.
Materials:
•One-way hand pump (1)
• ½” clear plastic tubing (approx. 4 ft.)
•Bucket (1)
•Plastic zip ties (approx 10)
Background: The flow of electricity is readily compared to the flow of water. A water hand
pump will be used to illustrate the flow of electricity in a close circuit. The water is moved
when the pump is pulled upwards. The pressure applied during this upward stroke is
analogous to the voltage in an electric circuit, and the speed of the flowing water is similar
to the current. If more force is applied during the upward stroke, the water will move faster,
just as more voltage increases current in a circuit. Lastly, the diameter of the tubing is
similar to the resistance in a circuit. A smaller diameter tube is the same as a higher level of
resistance. So, in the water loop, if the tube diameter is decreased, the water will move
faster if the same pressure is applied, or a smaller pressure must be applied to get the same
speed of flow. This relationship between water pressure, water speed, and tube diameter
clearly illustrates Ohm’s law (voltage (V) = current (I) x resistance (R)).
Preparation: Attach the plastic tubing to the pump inlet on the bottom. Then, place the
other end of the tubing in a bucket full of water and pump a few times to draw water into
the pump. Take care to pump slowly, as water will pour out of the side outlet once the
pump is full and pumping too hard will spray water everywhere. Next, close the loop by
attaching the open end of the tubing to the pump’s side outlet. Try to minimize the
amount of air in the tube, so that air bubbles do not interfere with the demonstration.
The left image shows the pump being filled, followed by the closed loop on the right.
Instructions: As described above, this closed water loop demonstrates Ohm’s law. Have
students use the hand pump to see the relationship between hand pressure and the speed
of the water flow. Then, tighten the pipe with a zip tie to simulate increased resistance.
Students should observe that the same amount of force moves the water at greater speeds.
10
<< DEMONSTRATION 2: MAGNETIC FORCE AT WORK >>
Goal: To illustrate the movement of a magnet by a wire coil
Materials:
• Bar Magnet (1)
• 30AWG enamel wire (approx. 10 ft.)
• D-cell battery holder with switch (1)
• D-Cell Battery (1)
• Plastic Sleeve (1)
• Small piece of sandpaper (1)
Instructions: Coil the wire tightly around the plastic sleeve, keeping about two inches of
slack at the beginning for connection to the battery holder. Coil the wire neatly and evenly,
making sure that there is no space from one coil to the next. Then, use the sandpaper to
strip the enamel off both ends of the wire, and connect these ends to the two leads from
the battery holder, making sure the switch is off. Insert a magnet into the sleeve, so that it
is sitting close to the beginning of the coils. Once you connect the switch, the magnet
should jump a little bit in one direction or the other.
To make the magnet jumping more obvious, try tapping the switch rapidly. This
vibrates the plastic sleeve, and is a good first hand illustration of the fundamentals behind
a speaker.
SAFETY NOTICE: Due to the low resistance of the wire alone, keeping the switch on
more than 10 or 15 seconds will cause the wire to heat up.
11
DAY 3 briefing
<< DEMONSTRATION 4: AN ORDINARY SPEAKER VS. AN
EXTRAORDINARY SPEAKER >>
Goal: To compare and contrast the features and functionality of a typical computer speaker
(“ordinary speaker”) and the simple paper cup speaker (“extraordinary speaker”).
Materials:
 IPOD, (A portable CD player, or a standard headphone out jack of a computer
would work as well)
 2 standard computer speakers
 Constructed paper-cup speaker prototype
 Sound meter (1)
Instructions: Plug in your commercial audio player (or computer) to the standard audio
input plug of the computer speakers. Plug in the power adapter from the speakers into a
standard power outlet and play a reselected music selection for the student. Measure the
intensity of sound coming out of the speakers using the sound meter and have the students
make note (not necessary to record) of the different dB values as you adjust the volume of
the player. Next, disconnect the sound source from the speakers and connect the audio
input source to the pre-built prototype paper-cup speaker (which is constructed through the
instructions in the following section). Use alligator clips and to secure the wires on either
side of the connection. Once again turn on your sound source and measure the intensity of
sound coming from the paper cup speaker. The students should be able to hear a faint and
crackly sound coming out of the speaker but at a much lower volume than before.
SAFETY NOTICE: Using an audio source with a high output resistance (i.e. a boom box
“speaker out” output) will cause the connection wires to heat up which could in turn cause
the cup and/or wires to melt, and the internal boom box circuit breaker to trip.
12
<< ACTIVITY 3: Variations of a basic speaker >>
Instructions: Coil the wire tightly around the plastic sleeve, keeping about two inches of
1. Measure 4 inches of wire from the spool. While holding the wire to a pen of desired
diameter, begin wrapping the wire around the pen, leaving the 4 inches free so that it can
be used to connect the input to the speaker. Using your finger to hold the wire to the pen,
count the number of times that the wire passes your finger as you wrap the wire around the
pen. Each time you wrap the wire entirely around the pen, you create one coil. Be sure
not to wrap the wire around the pen too tightly, the coils will have to be removed from the
pen. After you have created the selected number of coils, cut the wire from the spool,
making sure to leave a second 4 inches to use as the other input connection of the speaker.
2. Using a small piece of sandpaper, remove the insulation from a length ½ inches from
the end of the two input wires.
3. Remove the coil from the pen. Using the scotch tape, attach the coil to the center of
the bottom of the cup. To do this, place the cup upside down on the work surface. Attach
the coil so that it is flat against the surface of the cup, leaving two 4-inch input wires free.
13
4. Using the scotch tape, attach the magnet on top of the coil. Again lay the magnet flat.
5. Attach one of the alligator clips from the connecting cable to one of the wires on your
cup speaker. Attach the other alligator clip to the remaining input wire on the speaker.
6. Plug the other end of the connecting cable into the microphone jack of your electronic
device. Make sure the volume of your electronic device is set to “high.”
7. Arrange the sound meter so that the microphone is pointed at the opening of your cup
speaker. Place the sound meter 6 in from the opening and turn it to the 70 dB range.
8. Play a pre-selected selection from a recorded song and use the sound meter to record
the intensity of the sound coming from your paper cup speaker.
Splitting Up Into Teams:
Students should be split up into groups of 2 or 3. Each group will be given (at random on
of the following design variations to explore). Each group will then test their design by
measuring the sound output (using the sound meter) and record their results on the
blackboard. Each student will copy down the results from the different groups and analyze
the implications of the different designs on a worksheet.
A. Paper cup, small magnet, d=¼” coil
B. Paper cup, donut magnet, d=¼” coil
C. Plastic cup, small magnet, d=¼” coil
D. Paper cup, small magnet, d=½” coil
E. Paper cup, donut magnet, d=½” coil
F. Plastic cup, small magnet, d=½” coil
Example Data Table:
# of Coils
15
20
25
14
Measured Sound Level (dB)
Students should be reminded to bring in materials from
home in order to design and build their own speaker!
Tips for selecting materials for building a good speaker:
When creating the speakers, seek rigid materials for the enclosure and flexible materials for
the diaphragm. If the enclosure and diaphragm are integrated, finding a material that is
partially rigid and partially flexible is best (e.g. paper cup).
 Integrated enclosure & diaphragm
o Styrofoam
o paper cups
 Enclosure
o
o
o
o
Plastic bottles
Cardboard
Construction paper
Wood
 Diaphragm
o
o
o
o
Paper
Rubber
Aluminum foil
Tape
Cross sectional view of a typical stereo speaker (6)
15
Day 4 Briefing
Discussion: How does an engineer differ from a scientist?
>> Engineers apply a logical methodology to develop solutions to practical problems.
The Engineering Design Process
<< ACTIVITY 4: OPEN BUILD >>
Goal: To expose students to the engineering design process, team building, optimization
and open-ended problem solving.
Materials:
• Small disk or donut magnet (1)
• 30AWG enamel wire (approx. 10 ft.)
• Plastic or paper cup (1)
• Students’ materials from home
• Sound Meter (1)
• Small piece of sandpaper (1)
Instructions: Starting with the basic prototype from the previous day, students should now
modify the design in order to achieve the highest possible volume output. They may use
appropriate materials that they brought in from home. This is a team activity and group
collaboration is encouraged and emphasized. Before and after the activity, each group
should take a few minutes to answer the guide questions on their worksheet.
16
DAY 5 briefing
<< Activity: TEAM DESIGN COMPETITION >>
Goal: To foster and encourage a healthy competitive attitude among the students, and to
give them the opportunity to observe the strengths and weaknesses of alternative solutions
to the problem (i.e. alternative designs)
Materials:
 Sound meter (1)
Instructions: The students should be given 2 minutes to come up with any last minute
“tweaks” with their design. The groups should then come up and measure their sound
output one by one and the results of each group should be recorder on the board. If time
permits, the groups can also give a brief (< 1min) explanation of their specific design and
why they think it worked well or poorly in the end. After each team has gone up and
measured its speaker’s audio output, the winner will be determined as the team with the
loudest speaker. The prize for winning the competition is at the discretion of the instructor.
Discussion and Review (approx 10 min., Q&A style):
(Key points to cover):
>> What is engineering? How is it different from science?
>> Who invented the first speaker? For what purpose?
>> How does sound travel?
>> Which scientific term essentially means “pitch?” What about “Volume?”
>> What is the basic idea behind electromagnetism?
>> What makes a speaker design better?
>> What is the first step in the engineering design cycle?
After reviewing the important concepts, the students will fill out an
evaluation survey dealing with their experiences throughout the weeklong
activity.
17
PICTURE CREDITS
(1) http://www.fiatluxphotos.com/photo_122946.html
(2) http://history.sandiego.edu/gen/recording/loudspeaker.html
(3)
http://en.wikipedia.org/wiki/Magnetic_field
(4)
http://en.wikipedia.org/wiki/Right_hand_rule
(5)
http://www.sciencebob.com/experiments/electromagnet.html
(6) http://www.emater.com/web3/images/services_001.jpg
(7) http://www.historyplace.com/specials/calendar/docs-pix/edison.jpg
(8) http://www.dyslexiamentor.com/2005assets/pics/leonardo-da-vinci.jpg
(9)
http://www.vintageskivvies.com/art/archives/history/massroduction/eliwhitney.jpg
(10) http://www.tonaufzeichnung.de/personen/alexander_bell2.jpg
(11) http://upload.wikimedia.org/wikipedia/de/thumb/a/a5/Rudolf-diesel.jpg/180px-Rudolf-diesel.jpg
(12) http://www.hopshop.net/tours/lighting_tour/images/nikola-tesla.jpg
(13) http://www.historyplace.com/specials/calendar/docs-pix/jimmy-carter2.jpg
(14) http://northernblue.ca/canchan/canpix/evenimag/18671900/BELLTEL.JPG
(15) http://northernblue.ca/canchan/canpix/evenimag/18671900/BELLTEL1.JPG
(16) http://www.webgraffix.com/PSPImages/Speaker.jpg
(17) http://www.hometheaterhifi.com/volume_3_3/images/osborn-titan-speakers-front-main.jpg
(18) http://www.localhistory.scit.wlv.ac.uk/Museum/Engineering/Electronics/AJShorn/loudspeaker.jpg
(19) http://www.cubeonline.org.uk/images/loudspeaker.gif
(20) http://www.thebakken.org/electricity/images-static/Franklin-kite-exp.jpg
(21) http://www-lecb.ncifcrf.gov/~toms/lightning.bolt.html
(22) http://www.physics.brocku.ca/courses/1p22/images/f21005.jpg
(23) http://particleadventure.org/particleadventure/frameless/electromagnetism.html
(24) http://viz.aset.psu.edu/gho/sem_notes/3d_fundamentals/html/3d_coordinates.html
(25) http://www.teslamotors.com
ADDITIONAL REFERENCES
(1) http://www.house.gov/fossella/Press/pr020611.htm
(2) Giancoli, D. C. (2000). Physics for Scientists & Engineers, 3rd Ed. Upper Saddle River, NJ: Prentice Hall.
18
Name:
Electricity Rocks!
(1)
Student Packet
19
Name:
DAY 1: Historically Speaking
As previously mentioned, engineers apply the principles of science to create new
technology which solves a problem and addresses a need in society. One good example the need for long-distance communication - was first addressed successfully in the 1870's.
The key players at the time, Alexander Graham Bell, Elisha Gray, and Antonio Meucci
each worked towards a common goal of developing a device that would allow two people to
talk to each other through a device that allowed them to be in different physical locations.
The patent, which was first awarded to Bell, described the new "telephone" as an "apparatus
for transmitting vocal or other sounds telegraphically." However in addition to transmitting
sound, the apparatus had to ensure that the users could hear each other. This was a huge
challenge to which the answer was first primitive loudspeaker, a transducer capable of
converting electricity to sound using a very straightforward implementation.
Alexander Graham Bell using his telephone (14)
Inside Bell’s first telephone (15)
Some different speaker styles:
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(17)
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Each type of speaker design employs the same concept of combining an electrical
current and a magnetic field to produce vibrations.
Transmission of Sound
In general, sound must be transmitted through a medium. The two most common
media for the transmission of sound are air and water. Sound travels faster in denser media,
so sound transmitted through water will travel faster than sound transmitted through air.
-- Can you think of an application of the transmission of sound through water?
-- What else can you transmit sound through?
20
Name:
DAY 1: What is engineering?
Starting today and for the next five days everyone in this room will become an
engineer. Ask the average person a hundred years ago what it is that an engineer does and
he would probably tell you "An engineer works on the railroad." Back then, that statement
would have been correct, but nowadays, it is practically a joke. So then what do engineers
do and moreover, what is engineering? To most people engineering and science mean
about the same thing: exploring the natural world and discovering new laws and such (oh
yeah, and lots of equations). In reality, engineering is very different from science. Engineers
apply the principles of science to create new technology which solves a problem of
addresses a need in society.
Who do you think of when the term engineer is mentioned?
Thomas Edison?
Famous Inventor
Leonardo Da Vinci?
Painter, inventor, engineer
(7)
Eli Whitney?
Inventor of the cotton gin
(8)
Alexander Graham Bell?
Invented the telephone
(9)
(10)
Rudolf Diesel?
Developed the diesel engine
Nikola Tesla?
Developed alternating current
(11)
Jimmy Carter?
39th President/Nuclear Engineer
(12)
(13)
21
Name:
DAY 1: SoundS GREAT!
Sound is energy transmitted in waves. Each sound wave is characterized by its own
amplitude, frequency and wavelength. These characteristics also describe the pitch and the
volume of the transmitted sound.
AMPLITUDE: the distance from the resting position to either the crest or the trough
of the wave
FREQUENCY: the number of waves that pass a point during one second, expressed
as Hertz, (Hz).
WAVELENGTH: the distance between a point on one wave and the identical point
on the next wave
PITCH: the highness or lowness of a sound, and is determined by the frequency and
wavelength of the sound wave.
VOLUME: the loudness of a sound (measured in decibels, or dB), and is determined
by the amplitude of the sound wave.
<< ACTIVITY: RULER TONES>>
How can you vary the amplitude of the sound waves created by holding one end of a ruler
on the desk and smacking the other end?
How about varying the frequency? The wavelength?
22
Name:
DAY 2: IT’S ELECTRIC!
“Energy and persistence drive all things”
-- Benjamin Franklin
Ever been struck by lighting? Benjamin Franklin was, and even he lived to tell about it.
What he went on to tell was the story of electricity: its existence not only in the form of
lightning but in ordinary things around us. By now you have probably studied electricity
many times, but today you’re going to develop an intuitive feel for it really is!
Depiction of Franklin’s famous kite experiment (20)
Lightning strikes the ground (21)
CHARGE: a property of matter (like weight or height) that represents the quantity of
unbalanced electricity in a body. It can be either positive or negative (that much you
already knew) and is measured in terms of the unit Coulomb ( C ).
ELECTRONS: negatively charged particles (i.e. very tiny “things”). How tiny? Well, each
electron weighs only 0.0000000000000000000000000000000919 kg
ELECTRIC CURRENT: which is abbreviated with the symbol “I” and simply means how
many electrons are flowing (traveling) per unit time. The unit of current is Amperes, (A)
and is equivalent to Coulombs/sec. So naturally this means that the more electrons we
have and the faster they are traveling (flowing) the more current we have.
VOLTAGE: Imagine holding a basketball a few inches off of the ground. If you dropped it
on your toe from this height, it probably wouldn’t hurt; but what about if you dropped it
from 2 stories up? The ball’s potential energy is a lot higher so dropping it this time would
most surely hurt! Now imagine doing the same thing except this time instead of 1
basketball, you have one hundred. Intuitively, how much greater would the impact be then?
Answer:
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_________ times
If instead of holding basketballs you’re holding electrons, we can think of their potential
energy as proportional to their height off the ground. We have already determined that
dropping 100 basketballs on your foot from this height is A LOT worse than dropping just
one, so there we have it:
The difference in potential energy per unit of charge (i.e. the drop height per
basketball) is known as VOLTAGE.
RESISTANCE: What if instead of dropping the original basketball through air from 2
stories up, we dropped it instead into a big vat of honey that was 2 stories deep? Would it
be harder for the ball to fall in this case or easier?
Answer: __________________
The difficultly with which a charge travels through some medium is known as the
RESISTANCE of that medium, abbreviated R, and measured in terms of Ohms (Ω).
<< DEMO: CURRENT  WATER PUMP >>
The last and perhaps most useful term left to define is ELECTRICAL POWER. Power is
defined as the amount of electrical energy per unit time and its unit is Watts (W).
You may be more familiar with electrical power by its common name: ELECTRICITY!
VOLTAGE = CURRENT x RESISTANCE

V=IxR
POWER = VOLTAGE x CURRENT

P=IxV
Use your new electrical intuition to answer the following Questions:
More Resistance + Less Voltage = __________ Current
More Voltage + Less Current
= __________ Resistance
More Current + More Resistance = __________ Power
In cars, engine power is
measured in units of
Horsepower:
<<1 Horsepower = 745.7 Watts>>
The 2006 100%-electric, 248-horsepower Tesla Roadster (26)
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Name:
DAY 2: Got magnetism?
If you have ever used a compass, you might have heard that the compass “North” actually
points to the Earth’s south geographic pole. The Earth (like a refrigerator magnet) has its
own MAGNETIC FIELD, B (with units of Tesla, T) which points from the North to the
South MAGNETIC POLES. This field essentially represents the MAGENTIC FORCE of
the magnet acting at a distance from the poles.
(22)
Many materials exhibit naturally magnetic properties, the most common of them being
iron. The Earth’s innermost core is made up of molten iron which is essentially
responsible for Earth’s strong magnetic field – think of it as a very large bar magnet.
<< DEMO: MAGNETIC FORCE >>
Like oppositely charged particles, opposite magnetic poles attract while like poles repel.
This behavior is more than just a striking coincidence but in fact demonstrates the strong
fundamental relationship between electricity and magnetism. This can be summarized as:
Electricity INDUCES Magnetism
And
Magnetism INDUCES electricity
This essentially means that there is no separate electric force
(between charges) and magnetic force (between poles). They
are both the same force acting in different ways, and this
is the basic principle known as ELECTROMAGNETISM.
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Name:
DAY 2: ELECTROMAGNETIC INDUCTION
Right Hand Rule:
Version I.>
Start with your right palm open and the thumb
pointing upward. Your thumb represents the
direction of the flow of current. If you curl the
fingers of your right hand towards your palm,
then your curled fingers will point in the
direction of the resulting magnetic field that will
arise from the flow of current (your thumb).
Version II.>
Start with your right palm open and the thumb
pointing upward. Curl the fingers of your right
hand towards your palm to represent the flow of
current in a circular coil of wire. Your thumb will
point in the direction of the resultant magnetic
field induced from the flow of current.
The number of coils through which the current travels has an effect on the magnetic field.
Question: Intuitively, what do you think happens to the strength of the magnetic
field as we increase the number of coils though which the current is flowing?
Answer:___________________________________________________________
The Right Hand Rule is a visual illustration of ELECTROMAGNETIC INDUCTION:
the physical explanation of the inseparable nature of electricity and magnetism. It is the
basis behind the operation of virtually all electrical devices in the world today. The concept
was discovered long ago but was finally harnessed at the beginning of the 20th century by a
brilliant engineer named Nikola Tesla. His discovery known as ALTERNATING
CURRENT explains the electricity that comes out of your wall outlet and operates like this:
By flipping the direction of the current flowing through a circuit every X seconds we are
able to toggle the resultant magnetic field back and forth. This periodic flip generates a sort
of push and pull action on a permanent magnet placed in the vicinity of the varying
magnetic field. Can you think of any reasons why this might be a useful thing?
Answer:__________________________________________________
_____________________________________________________________
<<ACTIVITY: MAKING AN ELECTROMAGNET>>
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Name:
DAY 3: Building a Speaker
<< DEMO: AN ORDINARY SPEAKER VS. AN EXTRAORDINARY
SPEAKER >>
1. Measure 4 inches of wire from the spool. While holding the wire to a pen of desired
diameter, begin wrapping the wire around the pen, leaving the 4 inches free so that it can
be used to connect the input to the speaker. Using your finger to hold the wire to the pen,
count the number of times that the wire passes your finger as you wrap the wire around the
pen. Each time you wrap the wire entirely around the pen, you create one coil. Be sure
not to wrap the wire around the pen too tightly, the coils will have to be removed from the
pen. After you have created the selected number of coils, cut the wire from the spool,
making sure to leave a second 4 inches to use as the other input connection of the speaker.
2. Using a small piece of sandpaper, remove the insulation from a length ½ inches from
the end of the two input wires.
27
3. Remove the coil from the pen. Using the scotch tape, attach the coil to the center of
the bottom of the cup. To do this, place the cup upside down on the work surface. Attach
the coil so that it is flat against the surface of the cup, leaving two 4-inch input wires free.
4. Using the scotch tape, attach the magnet on top of the coil. Again lay the magnet flat.
5. Attach one of the alligator clips from the connecting cable to one of the wires on your
cup speaker. Attach the other alligator clip to the remaining input wire on the speaker.
6. Plug the other end of the connecting cable into the microphone jack of your electronic
device. Make sure the volume of your electronic device is set to “high.”
7. Arrange the sound meter so that the microphone is pointed at the opening of your cup
speaker. Place the sound meter 6 in from the opening and turn it to the 70 dB range.
8. Play a pre-selected selection from a recorded song and use the sound meter to record
the intensity of the sound coming from your paper cup speaker.
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Name:
DAY 3: BUILDING WORKSHEET
<< DEMO 4: AN ORDINARY SPEAKER VS. AN EXTRAORDINARY
SPEAKER >>
What design options were you assigned?
No. of Coils ___________
Diameter of Coils______________
Record your results below:
Magnet Type:
Small
Donut
Small
Cup Type:
Paper
Paper
Plastic
Measured Sound Level (dB)
1. It is important which alligator clip is attached to which wire? Why do you think this is?
2. Why is it important to play a pre-selected selection from a recorded song? Remember
you will be attempting to optimize your speaker design!
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Name:
DAY 3: Results TABLE
A. Paper cup, small magnet, d=¼” coil
Measured Sound Level
# of Coils
(dB)
15
20
25
B. Paper cup, donut magnet, d=¼” coil
C. Plastic cup, small magnet, d=¼” coil
D. Paper cup, small magnet, d=½” coil
# of
Coils
15
20
25
# of Coils
15
20
25
Measured Sound Level
(dB)
# of Coils
Measured Sound Level
(dB)
15
20
25
E. Paper cup, donut magnet, d=½” coil
# of Coils
Measured Sound Level
(dB)
F. Plastic cup, small magnet, d=½” coil
Measured Sound Level
(dB)
# of Coils
Measured Sound Level
(dB)
15
20
25
15
0
25
3. Comparing values in each table, which no. of coils produced the loudest sound? Why?
4. Comparing values in tables A and B which magnet produced the loudest sound? Why?
5. Comparing values in tables A and C, which cup produced the loudest sound? Why?
6. Comparing values in tables A, B, and C with those in D, E, and F, which coil diameter
produced the loudest sound? Why?
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For next class remember to bring in materials from home
in order to design and build your own speaker!
Here are some tips for selecting materials to build your own speaker:
When creating the speakers, seek rigid materials for the enclosure and flexible materials for
the diaphragm. If the enclosure and diaphragm are integrated, finding a material that is
partially rigid and partially flexible is best (e.g. paper cup).
 Integrated enclosure & diaphragm
o Styrofoam
o paper cups
 Enclosure
o
o
o
o
Plastic bottles
Cardboard
Construction paper
Wood
 Diaphragm
o
o
o
o
Cross sectional view of a typical stereo speaker (6)
Paper
Rubber
Aluminum foil
Tape
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Name:
Day 4: Design, TEST, REPEAT…
How does an engineer differ from a scientist?
A scientist may perform an experiment to determine the thrust produced by a rocket. On
the other hand, an engineer may take the results of the experiment and design a better
rocket or a vehicle that uses the rocket. Let’s look at engineering design in detail.
The Engineering Design Process
Engineers apply a step-by-step design process to develop solutions to problems.
Identify
Problem
Brainstorm
Ideas
Develop
Design
Revise
Design
Test Design
Develop
Final Report
How can this methodology be applied to the design of a speaker?
32
<< ACTIVITY: OPEN BUILD >>
Before you get started with your design take 5 minutes to answer the following questions:
1. What is your design problem?
2. Brainstorm some ideas here:
3. What design did you select to build and why?
For the last five minutes of class, answer the following questions regarding your design.
4. What worked well in your first design?
5. What did not work well in your first design?
6. What changes are you going to make to your design and why?
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Name:
DAY 5: Evaluation Survey
1.)
How much did you learn (really) ?
1
2
3
4
Not at All
2.)
2
3
4
10
Very Much!
5
6
7
8
9
10
Very Much!
2
3
4
5
6
7
8
9
No Opinion
10
Very Much!
How successful was your speaker ?
1
2
3
4
Not at All
5
6
7
8
9
No Opinion
10
Very Much!
How much did you enjoy working in a team?
1
2
3
4
Not at All
5
6
7
8
9
No Opinion
10
Very Much!
How much did everyone on your team contribute?
1
2
3
4
Not at All
7.)
9
No Opinion
Not at All
6.)
8
How challenging was this experience?
1
5.)
7
No Opinion
Not at All
4.)
6
How much fun was this experience (really) ?
1
3.)
5
5
6
7
8
9
No Opinion
10
Very Much!
Are you more likely to go into engineering after this experience?
1
Not at All
2
3
4
5
6
7
No Opinion
8
9
10
Very Much!
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8.)
How well do you understand what engineering is about?
1
2
3
4
Not at All
9.)
5
6
7
8
9
No Opinion
10
Very Much!
How well do you understand sound?
1
2
3
4
Not at All
5
6
7
8
9
No Opinion
10
Very Much!
10.) How well do you understand electricity and magnetism?
1
2
3
4
Not at All
5
6
7
8
9
No Opinion
10
Very Much!
11.) How well do you understand the design process?
1
2
3
4
Not at All
5
6
7
8
9
No Opinion
10
Very Much!
12.) Were the UVA students effective teachers?
1
Not at All
2
3
4
5
6
7
No Opinion
8
9
10
Very Much!
13.) What were we trying to teach you?
14.) What was best part about this experience?
15.) What about the worst part?
35