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What Wavelength Was That?
Mr Hemming
Examining the Electromagnetic Spectrum
with Hands-On Activities
Electromagnetic Waves
• All travel at the speed of light, 300,000 km /s. (That’s 8 times around the earth in a second!)
• All can travel through empty space (a vacuum)• All can be reflected or refracted• The shorter the wavelength the more dangerous
they are• They all transmit energy from one place to another
Electromagnetic Radiation
• The only difference between radio waves, visible light, and gamma-rays is the energy of the photons.
• Radio waves have photons with low energies, microwaves have a little more energy than radio waves, infrared has still more, then visible, ultraviolet, X-rays, and gamma-rays.
Radio(Low Frequency & Very High Frequency)
• Emitted by– Astronomical Objects– Radio Station
transmitters
• Detected by– Ground based radio
telescopes– Radios
Microwave
• Emitted by:– Gas clouds collapsing
into stars– Microwave Ovens– Radar Stations– Cell Phones
• Detected by– Microwave Telescopes– Food (heated)– Cell phones– Radar systems)
Infrared(Near and Thermal)
• Emitted by– Sun and stars (Near)– TV Remote Controls– Food Warming Lights
(Thermal)– Everything at room
temp or above
• Detected by– Infrared Cameras– TVs, VCRs,– Your skin
Visible
• Emitted by– The sun and other
astronomical objects– Laser pointers– Light bulbs
• Detected by– Cameras (film or
digital)– Human eyes– Plants (red light)– Telescopes
Ultraviolet
• Emitted by– Tanning booths (A)– The sun (A)– Black light bulbs (B)– UV lamps
• Detected by– Space based UV
detectors– UV Cameras– Flying insects (flies)
X-ray
• Emitted by– Astronomical objects – X-ray machines– CAT scan machines– Older televisions– Radioactive minerals– Airport luggage scanners
• Detected by– Space based X-ray
detectors– X-ray film– CCD detectors
Gamma Ray
• Emitted by– Radioactive materials– Exploding nuclear
weapons– Gamma-ray bursts– Solar flares
• Detected by– Gamma detectors and
astronomical satellites– Medical imaging detectors
X-rays and Gamma Rays
• Black holes• Active Galaxies• Pulsars• Diffuse emission• Supernovae• Gamma-ray bursts• Unidentified
The Multiwavelength Sun
X-Ray UV Visible
Infrared RadioMicrowave
A Mnemonic for the Electromagnetic Spectrum…
– Gamma Rays– X-rays– Ultraviolet– Visible– Infrared– Microwave– Radio
A CONTEST!!!