Scaling the Electromagnetic Spectrum
David W. Rhyne, Educator, MathScience Innovation Center
Developed with funding from the MathScience Innovation Center.
Adapted from Jones, Gail, Taylor, Amy & Falvo, Michael. (2009).
Screening My Calls: Scale and the Electromagnetic Spectrum.
Extreme Science: From Nano to Galactic. (pp. 293-303). NSTA
Press.
Major
Understanding
The electromagnetic (EM) spectrum delineates the most significant energy in
the Universe. All this energy comes to us in the same form, and the differences
are defined solely by scale. The EM spectrum wavelengths range from the
macro scale that we live in through the familiar micro scale and the less
familiar nano scale to the atomic and pico scale. Understand that scale allows
us to use vital components of the EM spectrum while protecting ourselves
from unwanted intrusions or even danger.
Grade/Subject
Grade 6 Science, Physical Science, Technology, Physics
Objectives
Explain the relationships between wavelength, frequency and energy
in the EM spectrum.
Investigate how Faraday cages block or screen wavelengths of the
EM spectrum.
Use scientific notation to define the scale of the EM spectrum.
Explain why “Size and Scale” is the first of the Big Ideas of
Nanoscale Science and Engineering.
Time
Background: Big Ideas of Nanoscale Science and Technology
Properties of the EM Spectrum Scale
Activity: Wave Properties
Demonstration: Faraday Cages
Activity: Control Experiments
Activity: Screening Signals
Activity: Determine Wavelengths
Activity: Building Faraday Cage
Demonstration: Share
Closure
Practice
Assessments
Scaling the Electromagnetic Spectrum
http://MathInScience.info
5 min
10 min
10 min
5 min
10 min
10 min
10 min
15 min
5 min
2 min
Variable
Variable
© MathScience Innovation Center, 2012
Materials
For the class:
 Computer
 Projector
 PowerPoint
 AM/FM portable radio
 Prebuilt Faraday cage using wish mesh (optional)
For each group of students:
 Cell phone (optional) and/or small radio
 Aluminum foil
 Aluminum screening material
 Aluminum tape
 Small boxes (large enough to hold cell phone or small radio)
 Scissors
 Ruler
State and National
Correlations
Virginia Standards of Learning: 2010 Science (PS.6, PS.9, PH.8, PH.9,
PH.12); 2009 Math (6.5, 7.1, 8.1).
National Science Education Standards: Physical Science: Transfer of Energy;
Science in Personal and Social Perspectives: Science and Technology in
Society
NCTM Standards: Understand appropriate use of exponential and scientific
notation. Develop understanding of very large and small numbers.
Instructional
Strategies
1. Background on Big Ideas of Nanoscience and Technology
1.1. Discuss size and scale in the context of the Big Ideas (PowerPoint
Slides 1-4). Due to its nature, the Electromagnetic (EM) Spectrum
serves as an ideal medium to discuss scale and its effect on properties.
1.2. Introduce the nature of the EM scale with the video What the Heck is
Light, which is linked on Slide 5.
2. General Properties of the EM Spectrum
2.1. Use Slides 6-8 to discuss properties of the EM Spectrum focusing on
wave properties and wavelength. Slide 6 shows wavelength and energy
using scientific notation and illustrates the inverse relationship
between these two features. Common names for waves are at the
bottom.
2.2. Visible light is just outside the nanoscale (generally defined as 1100nm) (Slide 7), while X-rays are at the bottom of the scale—note the
increasing power as wavelength gets shorter (Slides 7-8).
Scaling the Electromagnetic Spectrum
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© MathScience Innovation Center, 2012
Practice
3. Activity: Wave Properties of Light
3.1. Slide 9 links to an applet at http://phet.colorado.edu/sims/wave-on-astring/wave-on-a-string_en.html. Use the applet to complete the
“Activity: Wave Properties.” This activity can be completed as a
whole class or small group activity (provided students have computers
with Internet access).
3.2. Students complete Questions 1 and 2 on the Activity Sheet.
3.3. Use Slides 10-13 to review wave properties of light and point out the
dual (particle) nature of light with photons. Slide 11 illustrates the
photoelectric effect which was used to prove the particle nature of
light. Slide 12 illustrates the relationship between electricity and
magnetism in the EM Spectrum. Optical properties of some substances
can be very different based just on scale. Slide 13 shows gold particles
of different sizes (within the nanoscale) suspended in solution. Note
the different colors (optical properties) illustrating how wavelengths of
visible light are refracted (bent) differently by the different size
particles. A similar phenomenon involving oxygen and nitrogen
molecules explains why the sky is blue.
4. Blocking Out Signals: Faraday Cages
4.1. Show video linked in the picture on Slide 14 demonstrating a grounded
Faraday cage under high voltage. Video is at
http://www.youtube.com/watch?v=bZwlD-Z0zmE. The link to the text
in the same slide shows an airplane being struck by lightning
(http:/www.youtube.com/watch?v=5IRfbC0RHsY).
4.2. Use Slide 15 to discuss how Faraday cages, first invented by Michael
Faraday in 1836, work. Made from conducting material cages divert
EM charges to the outside, making the cage a hollow conductor.
Inside the cage the charges are cancelled, depending on the
effectiveness of the conducting material.
5. Activity: Control Experiments
5.1. Slide 16 outlines materials needed for several experiments to follow.
These materials can vary depending on availability and student
abilities.
5.2. Conduct the Control Experiment (Slide 17) outlined in Step 1 of the
“Activity: Experimenting With Faraday Cages.” You can save class
time by pre-wrapping the boxes (not the lids) in aluminum. If you
want to reuse the boxes repeatedly, you may want to wrap a layer of
polyester film (e.g., Mylar®) on top of the aluminum to protect the
aluminum from tearing. Be careful to leave an exposed aluminum edge
Scaling the Electromagnetic Spectrum
http://MathInScience.info
© MathScience Innovation Center, 2012
along the top rim of the boxes if you wrap them in polyester.
5.3. Repeat the experiment (Step 2 in “Activity: Experimenting With
Faraday Cages”) (Slide 18), but this time have both the boxes and the
tops wrapped so that the tops fits snuggly, making a good connection
between the aluminum on the boxes and tops.
5.4. Students complete Questions 3 and 4 on the Activity Sheet.
6. Activity: Screening Out Signals (Slide 19)
6.1. Provide participants with a square foot of aluminum screening
material. Precut the material to save time and wrap the edges in heavy
tape (duct tape) to protect against sharp edges. Conduct Step 3 of
“Activity: Experimenting With Faraday Cages.”
6.2. Students complete Question 5 on the Activity Sheet.
7. Activity: Determining Wavelength
7.1. Use Slide 20 to review the relationship between wavelength and
frequency. Have the participants complete Questions 6 and 7 on the
Activity Sheet.
7.2. Shorter wavelengths have higher frequencies and energy and are more
difficult to block. To block a signal with a Faraday cage using wire
mesh, you need a mesh size about 1/10th the wavelength. Higher
conductive materials (e.g., copper) work best.
8. Activity: Building a Faraday Cage
8.1. Conduct Step 4 in the “Activity: Experimenting With Faraday Cages”
(Slides 22- 23).
Answer Question 8 on the Activity Sheet.
Closure
Discuss results of experiments (Slide 23). Discuss why understanding
wavelength and frequency matters. Point out locations where wireless
equipment will not work (Slide 24). Note the increasing need for electronic
security measures to protect against theft (financial and personal information,
national security). Point out that space weather (radiation from the sun) can
create electronic challenges and beautiful aurora borealis and can be dangerous
in space travel. Electromagnetic pulse (EMP) is being studied as a weapon to
knock out an enemy’s electronic signals and command structure.
Extensions
1. Faraday Cages. Have students design and build their own Faraday cages.
Several designs can be found on the Internet. Have them explain what
materials would make the best cages.
Scaling the Electromagnetic Spectrum
http://MathInScience.info
© MathScience Innovation Center, 2012
2. Frequency Allocations. Have students conduct Internet research on
government frequency allocations. Explain why the government allocates
frequencies. How do allocations in the U.S. differ from other countries or
regions.
Assessment
Sample items are provided for use in checking students’ understanding.



Experimenting with Wavelength and Faraday Cages Solution Sheet
Paper Pencil Assessment
Product and Rubric
The following table shows how the assessment items are related to specific
objectives.
Objective
PaperPencil Test
Explain the relationships between
wavelength, frequency and energy in the EM
spectrum.
4,5,8,9
Investigate how Faraday cages block or
screen wavelengths of the EM spectrum.
6,7,8
Use scientific notation to define the scale of
the EM spectrum.
2
Explain why “Size and Scale” is the first of
the Big Ideas of Nanoscale Science and
Engineering.
1,3
Major Understanding
Teaching Tips
Product/
Performance
Project and
Rubric
Student
1. Some tips about the materials used in this lesson:



Any container made with good conductive material can serve as a
Faraday cage/box.
Boxes wrapped in aluminum foil can be protected from wear and tear
by adding a layer of Mylar® plastic.
Aluminum foil may need to be replaced around boxes periodically due
to wear and tear.
2. Where do we get the supplies:
Scaling the Electromagnetic Spectrum
http://MathInScience.info
© MathScience Innovation Center, 2012



Portable AM/FM radios are readily available at reasonable prices on
many websites.
Boxes large enough to hold radios are found at craft stores.
Materials to build a Faraday cage can be found at local hardware stores.
3. What are the answers to the Paper/Pencil Test?
1. e
2. b
3. b
4. b
5. c
6. a
7. a
8. b
9. a
References
Building a Faraday Cage – Why and How
Visit this site for background on Faraday cages and how to build them.
http://snallabolaget.com/?page_id=1102
Interactive Simulations, University of Colorado
Visit this site for a variety of computer simulations, including “Wave-on-aString” used in this lesson.
http://phet.colorado.edu/en/simulation/wave-on-a-string
MathScience Innovation Center
Information on educational programs available to students, teachers and school
divisions and procedures for registering for programs.
http://www.msinnovation.info
MathScience Innovation Center: On-Line Educational Programs
Learn through on-line virtual classrooms, web-based lessons, and on-line
courses. Access proven lesson plans and instructional modules.
http://mathinscience.info
National Science Teachers Association
Jones, Gail, Taylor, Amy & Falvo, Michael. (2009). Screening My Calls: Scale
and the Electromagnetic Spectrum. Extreme Science: From Nano to Galactic.
(pp. 293-303). NSTA Press.
This book focuses on scale from the very large to the very small, the
importance of scale in life and how to incorporate scale in teaching.
Stevens, Shawn, Sutherland, LeeAnn & Krajcik, Joseph. (2009). The Big Ideas
of Nanoscale Science and Engineering: A Guidebook for Secondary Teachers.
NSTA Press.
This book is a guide for secondary teachers incorporating nanoscale science
and engineering into the classroom.
http://www.nsta.org/recommends/
Scaling the Electromagnetic Spectrum
http://MathInScience.info
© MathScience Innovation Center, 2012
YouTube
Search for brief video clips on a variety of topics, including “What the Heck is
Light” and Faraday cages.
http://www.youtube.com
Scaling the Electromagnetic Spectrum
http://MathInScience.info
© MathScience Innovation Center, 2012