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!!!