SCALING THE ELECTROMAGNETIC SPECTRUM Boxing out waves
Transcript
Slide 1
SCALING THE ELECTROMAGNETIC SPECTRUM Boxing out waves
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The First Big Idea Scale describes matter and predicts
behavior.
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The Other Big Ideas of Nano Structure of Matter Forces and
Interactions Quantum Effects Size-Dependent Properties
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Other Big Ideas - continued Self-assembly Tools and
Instrumentation Models and Simulations Science, Technology, and
Society
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An Amazing Scale More than you can see
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Wavelength is the Key What we see is much less than what we
get. Opensource Handbook of Nanoscience and
NanotechnologyOpensource Handbook of Nanoscience and
Nanotechnology. Illustration by Kristian MolhaveKristian
Molhave
Electromagnetic Energy Determined by wavelength and frequency.
E = mc 2 c = 2.9979 x 10 8 m/s
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Dual Nature of Light Light is also photons (particles) Zero
mass and zero rest energy Can be destroyed and created Can have
particle-like interactions with matter
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Electricity and Magnetism Magnetism and electricity move
together in the EM spectrum. Diagram from Schneider, Remote Sensing
and the Global Environment, http://www.geo.mtu.edu/rs/back/spectrum
/
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Appearances May Deceive Optical properties vary at the
nanoscale. Image source: L. R. Hirsch, R. J.Stafford, J. A.
Bankson, S. R. Sershen, B. Rivera, R. E. Price, J. D. Hazle, N. J.
Halas, & J. L. West, Proc. Natl. Acad. Sci. USA, 100, 13549-
13554 (2003). Proc. Natl. Acad. Sci. USA
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Blocking Out Signals Faraday Cage
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How does it work?
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Blocking Signals Activities Materials Needed Cell phone or
small radio Small box with lid Aluminum foil Aluminum screen
Scissors Tape and/or stapler ruler
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Activity Control Experiment 1. Turn on radio and set in box. 2.
Place lid on box. 3. Turn off radio. 4. One (or more) group test
with cell phone if available.
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Activity Box the Signal Wrap box and lid separately in aluminum
foil (ensure snug fit). Set radio in box. Open box slightly
(experiment with opening size). One (or more) group test with cell
phone if available.
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Activity Screen the Signal Make a cylinder with aluminum
screen. Leave one end open. Make a prediction. Place radio inside.
Close other end of cage. Test with a cell phone if available.
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Wavelength and Frequency Activity Wavelength c/f C = 3.0 x 10 8
m/s Example 300,000,000m/s) / (540,000 Hz) = 55.6 m Frequencies AM
radio: 540-1640 KHz FM radio: 88-174 MHz Cell: 850-1900 MHz
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What Size Mesh Do You Need? Mesh size 1/10 the wavelength
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Activity: Building a Faraday Cage Remove foil from top of box
lid. Cut several strips of foil. Make a grid of strips on the lid.
Experiment with size openings until a phone will not ring in
box.
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Data Analysis and Conclusions When using aluminum strips, what
size openings worked to stop the radio? A cell phone? Why does the
opening size matter in a Faraday Cage? What other materials could
be used?
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Wavelength Matters Locations where wireless equipment does not
work Protection from electronic spies Space weather effects
EMP