What Wavelength Was That?Examining the Electromagnetic Spectrum

with Hands-On Activities

Electromagnetic Spectrum

• The full range of frequencies, from radio waves to gamma rays, that characterizes light

• The electromagnetic spectrum can be expressed in terms of energy, wavelength, or frequency. Each way of thinking about the EM spectrum is related to the others in a precise mathematical way.

• The wavelength equals the speed of light divided by the frequency or lambda = c / nu

Electromagnetic Radiation

• Electromagnetic radiation can be described in terms of a stream of photons, each traveling in a wave-like pattern, moving at the speed of light and carrying some amount of energy.

• 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.

Scaling the Spectrum Activity

• Helps to explain the electromagnetic spectrum and dispels some of the common misconceptions.

• Paper and pencil project that requires the use of math skills as well.

Wavelength and Frequency

• For any kind of wave there exists a simple relationship between wavelength and frequency.

• The wavelength is measured as the distance between two successive crests in a wave. The frequency is the number of wave crests that pass a a given point in space each second.

Understanding Waves

• The traditional “slinky lab” as well as other activities to help understand waves.

• An activity that allows students to experiment with waves-longitudinal and transverse.

• Found in “Waves Light Up the Universe” Booklet

Radio(Low Frequency & Very High Frequency)

• Emitted by– Astronomical Objects– Radio Station

transmitters

• Detected by– Ground based radio

telescopes– Radios

Umbrella Receiver Demo

• Students discover a method of collecting radio frequencies by using an umbrella receiver.

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

Herschel’s Experiment

• Herschel’s Experiment– Discovered Invisible

Light– In 1800, Herschel

places his control thermometer just outside the red end of the spectrum

– Result: The outside thermometer registered the highest temperature

Conducting Herschel’s Experiment

• Set up of Box Design for Conducting the Herschel Experiment.

Conducting Hershel’s Experiment• Place a sheet of white paper

inside a cardboard box• Tape three thermometers

together and place inside box

• Cut a small notch in the top of the box and position a glass prism so that the spectrum is projected inside the box

• Arrange the thermometers so that one is just outside the red end of the spectrum, with no visible light falling on it

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

Roy G. Biv Activity

• Students will discover and verify the relationship between the Wavelength and Frequency of the EMS.

• Students compare the wavelength and frequencies of three colors of the visible light portion on the spectrum.

Red Sky – Blue Sky

• A demonstration used to illustrate how the gases in the atmosphere scatter some wavelengths of visible light more than others.

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

Chandra X-ray Observatory

• Chandra is designed to observe X-rays from high energy regions of the universe, such as the remnants of exploded stars.

• The most sophisticated observatory built to date.

• Deployed by the Space Shuttle Columbia on July 23, 1999,

Chandra X-ray Observatory

Gamma Ray

• Emitted by– Radioactive materials– Exploding nuclear

weapons– Gamma-ray bursts– Solar flares

• Detected by– Gamma detectors and

astronomical satellites– Medical imaging detectors

Sources of g-ray Emission• Black holes• Active Galaxies• Pulsars• Diffuse emission• Supernovae• Gamma-ray bursts• Unidentified

Source/Detector Activity

• Students identify sources (emitters) and detectors of the various wavelengths of the EMS.

• Students also have the opportunity to experiment with shields –or types of materials that prevent the transmission of wavelengths.

Exploring the EMS withNASA Missions

ASTRO-E2

Chandra

CHIPS Con-X

GALEXGLAST

HETE-2

INTEGRAL

MAP

RXTE

SWAS

XMM-Newton

Swift

Energy (eV)

Radio Infrared Visible UV X-ray Gamma ray

And the universe for that matter!