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HigherFrequency
LowerFrequency
Name:TheElectromagneticSpectrumPOGILActivity
Wavelength(λ)-Units:m,cm,nmFrequency(ν)-the#ofwavesthatpassagivenpointinonesecond.Units:Hz,sec-1,waves/sec,1/secTherelationshipbetweenfrequency(f)andwavelength(λ)ofawaveisdescribedbytheequation Wavesspeed=frequencyXwavelengthORc=νλ Allelectromagneticradiationpropagatesataspeedofc=3.00x108m/sec (approximately186,000milespersecond)thisiscalledthespeedoflight!Whensolvingproblemsusingc(thespeedoflight)ν MUSTbeinHzorsec-1andλ�MUSTbeinmeters.Problems
1.Whatisthewavelengthofradiationwithafrequencyof6.24xl013sec-1?
2.Whatisthefrequencyofradiationwithawavelengthof2.20xl0-6nm?(1nm=10-9mor109nm=1m)3.Atelevisionrelaytransmitteroperatesatafrequencyof927.9MHz.Calculatethewavelengthofthesignalinnanometers.Isthisvisiblelight?(1MHz=1,000,000Hz) HowonearthwouldIknowifitisvisiblelight?Readontofindout!!TheNatureofElectromagneticRadiation
Electromagnetic radiation includes radio signals, microwaves, infrared, visible light, ultraviolet, X-rays, andgammarays.Onemodelofelectromagneticradiationisapropagatingwavethatispartiallyelectricinnatureandpartiallymagneticinnature.Thefollowingdiagramisapictorialdescriptionofthismodel:Thistypeofwaveiscalledanelectromagneticwave.TheElectromagneticSpectrumThe electromagnetic spectrum is an ordered list of all the types of electromagnetic radiation. Allelectromagneticradiationcanbedescribedusingthewavemodelorparticlemodelabove.Theonlydifferencebetween each type is thewavelength and frequency of the associated electromagneticwave. The types ofradiationandtheirwavelengthrangesareshowninthediagrambelow.Problems(Usethediagramsonthepreviouspagetoanswerthesequestions.)4.WhatisthedifferencebetweenanX-ray,light,andaradiowave?5.Whichtypeofelectromagneticradiationhas:
Electromagnetic Spectrum
Wavelength Type of Electromagnetic Radiation 5.55 m to 187 m OR (5.55X109 nm to 1.87X1011 nm) AM Radio 0.187 m to 5.55 m OR (1.87X108 nm to 5.55X109 nm) TV & FM Radio Waves
10 mm to 187 mm OR (1X107 nm to 1.87X108 nm) Microwave 750 nm to 1,000,000 nm Infrared (IR)
400 nm to 700 nm Visible spectrum 10 nm to 400 nm Ultraviolet (UV) Less than 10 nm X rays
Less than 0.001 nm Gamma (γ) rays
electric part of wave
magnetic part of wave
direction of propagation
(a) thelongestwavelength?
(b) theshortestwavelength?
(c) thehighestfrequency?
(d) thelowestfrequency?
6.Whatistheapproximaterangeofwavelengthsofvisiblelight?Nowgobackandanswerquestions#3!7.Whatismeantbythestatement“Lightistheonlythingwecansee.”?ElectromagneticRadiationandEnergyElectromagnetic radiation carries energy with it over space. The energy of a photon (a particle ofelectromagneticradiationcarryingaquantumofenergy)isgivenbytheequation Energy=hXfrequencyORE=hν TheconstanthiscalledPlanck'sconstant,equalto6.63x10─34J●sec,averysmallnumber.Frequency(ν)–mustbeinHzorsec-1Anotherequationfortheenergyofaphotonis
Energy=hXspeedoflightORE=hcWavelength λ
Problems 8.Ifacertainlighthas7.18xl0-19Jofenergywhatisthefrequency,inHz,ofthislight?
b. Whatisthewavelength,innm,ofthislight?9.Ifthefrequencyofacertainlightis3.8xl014Hz,whatistheenergyofthislight?10.Theenergyofacertainlightis3.9xl0-19J.Whatisthewavelength,innm,ofthislight?Isitvisible?11. List the types of electromagnetic radiation in order from lowest energy photons to highest energyphotons.