Overview
Fromascientificpointofview,electromagneticwavesareatypeofenergyandbelongtoatypeofwave,justlikemechanicalwaves,gravitationalwavesandmatterwaves(probabilitywaves).)Similarly,allobjectshigherthanabsolutezerowillemitelectromagneticwaves,andthehigherthetemperature,thehigherthefrequencyoftheemittedelectromagneticwavesandtheshorterthewavelength.Thiselectromagneticwaveiscalledblackbodyradiation.Justaspeoplehavebeenlivingintheairbuttheireyescannotseetheair,inadditiontolightwaves,peoplecannotseeotherelectromagneticwaveseverywhere.
Electromagneticfieldincludestwoaspects:electricfieldandmagneticfield.ThecharacteristicsarerepresentedbyelectricfieldstrengthE(orelectricdisplacementD)andmagneticfluxdensityB(ormagneticfieldstrengthH)respectively.AccordingtoMaxwell'selectromagneticfieldtheory,thesetwopartsarecloselydependent.Atime-varyingelectricfieldcausesamagneticfield,andatime-varyingmagneticfieldalsocausesanelectricfield.Whenthefieldsourceoftheelectromagneticfieldchangeswithtime,themutualexcitationoftheelectricfieldandthemagneticfieldcausesthemovementoftheelectromagneticfieldtoformelectromagneticwaves.Thepropagationspeedofelectromagneticwavesisequaltothespeedoflight,infreespace,c=299792458m/s≈3×108m/s.Thetravelofelectromagneticwavesisalsoaccompaniedbythetransmissionofpower.
Electromagneticradiationisrelatedtotemperature.Generally,substancesorparticlesaboveabsolutezerohaveelectromagneticradiation.Thehigherthetemperature,thegreatertheradiation,thehigherthefrequency,andtheshorterthewavelength,butmostofthemcannotbeobservedbythenakedeye.arrive.
Attributes
Basicattributes
Electromagneticwaveshavethreemajorattributes,namelyamplitude(intensity,lightintensity),frequency(wavelength)andWaveform(spectraldistribution).Forvisiblelight,thesethreecorrespondtothebrightness,hueandchromaofthelightcolor.Forasinglefrequencyelectromagneticwave,thereisalsotheconceptofinitialphase,anditswaveformisasinecurve(cosinecurve)Thisiscalledasinewave(cosinewave).Theclosertheelectromagneticwaveistoasinewave,thepurerthespectrumandthebetterthemonochromaticity.Atypicalexampleislaser.
Animportantattributeofelectromagneticwavesisfrequency,whichcandeterminethevariouspropertiesofelectromagneticwaves,buttodescribethefrequencyofelectromagneticwaves,itisnotnecessarytousethefrequencyitself,Itcanalsobeaphysicalquantityrelatedtofrequency.Commonlyusedarewavelength(ifnodescriptionisgiven,defaultreferstothewavelengthinvacuum,whichistheonlycorrespondingrelationshipwithfrequencyandisinverselyproportional),photonenergy(Proportionaltofrequency),wavenumber(inverseofwavelength,proportionaltofrequency,defaultisthewavelengthinvacuum)andperiod(inverselyproportionaltofrequency),etc.
Physicalquantitysymbol
Frequency→forν(Greekletternew,notEnglishletterv,mostlyusedinquantummechanics),wavelength→λ,photonenergy→E,wavenumber→k(σandνareoftenusedinspectroscopy),period→T,speedoflight→c(invacuum)orv(inmedium)(wavelengthλ,wavenumberk,speedoflightcarealldefaultmeansinvacuum的)
Definingformula:f=1/T,λ=c/f(=c/ν),E=hf(=hν),k=1/λ
Conversionbetweenvariousphysicalquantitiesrelatedtoelectromagneticwaves
f(=ν)=c/λ=1/T=E/h=ck
λ=c/f(=c/ν)=cT=hc/E=1/k
E=hf(=hν)=hc/λ=hck=h/T
k=1/λ=f/c(=ν/c)=E/hc=1/cT
T=1/f(=1/ν)=λ/c=1/ck=h/E
Thepropagationspeed(wavespeed)ofelectromagneticwavesinvacuumisacertainvalue,thatis,thespeedoflight(invacuum),denotedasc,c=At299792458m/s,electromagneticwavescanpropagateinvacuumorinmedia,butthewavespeedinthemediumwilldecrease.Ingeneral,thewavespeedofelectromagneticwavesingas,liquid,andsolidwilldecreaseinsequence.Therefractiveindexnofthemediumtoacertainelectromagneticwaveisequaltothespeedoflightcinvacuumdividedbythespeedvoftheelectromagneticwaveinthemedium.Therefractiveindexofvacuumis1,therefractiveindexofgasisslightlygreaterthan1,andtherefractiveindexofliquidandsolidisgreaterthan1.Thegreatertherefractiveindex,thelowerthewavevelocityinthemedium.Ingeneral,inthesamemedium,thehigherthefrequencyofelectromagneticwaves(theshorterthewavelength),thegreatertherefractiveindex,andthelowerthewavespeed.Forexample,inthesamemedium,therefractiveindexofpurplelightislargerthanthatofredlight(thefrequencyofpurplelightishigherthanthatofredlight).Redlightishighanditswavelengthisshorterthanredlight).
Wave-particleduality
Allelectromagneticwaveshavewave-particleduality,andtheirparticleformiscalledphoton.Electromagneticwaveandphotonarenotblackorwhite,butaccordingtoThedifferenceinactualresearch,thetwoaspectsreflectedbyitsnature,theycoexist,youhavemeinyou,andyouinme.Formechanicalwavesandgravitationalwaves,therearealsotheircorrespondingparticleforms-phononsandgravitons.Amongthem,phononsarequasi-particlesandrequiretheexistenceofamedium,andgravitonsmaybebosonslikephotons,buttheyarestillItisakindofimaginaryparticlethathasnotbeenobservedbypeople.Accordingtothetheoryofquantummechanics,physicalparticlesalsohavevolatility.Suchwavesarecalledmatterwaves,ordeBrogliewaves.
Thestrengthofvolatilityandparticlepropertiesdependsonfrequencyandwavelength.Radiowavesaremainlyvolatility,andparticlepropertiesareextremelyweak;microwaveshavestrongvolatility,butalsohavecertainparticleproperties;infrared,visiblelightThevolatilityandparticlepropertiesofultravioletraysarerelativelyobvious,andtheyareinthetransitionzonebetweenvolatilityandparticleproperties;althoughX-raydiffractioncanalsooccur(X-raymicroscope),thevolatilityisweakandtheparticlepropertiesaremoreobvious(Comptoneffect),strongionizationability;gammaraysaredominatedbyparticles,withextremelystrongionizationability,andextremelyweakvolatility.
Electromagneticfield
Electromagneticfieldisaspecialformofmatter.Ithasthemainpropertiesofgeneralmatter,suchasmass,energy,momentum,etc.Objectively,therewillalwaysbeaunifiedelectromagneticfieldthathasnothingtodowiththeobservationconditions.Dividingitintotwoparts,theelectricfieldandthemagneticfield,isrelativeandisrelatedtothetestconditions.
Sphericalwave,cylindricalwaveandplanewaveForelectromagneticwavesthatchangesinusoidallywithtime,accordingtotheirelectricfieldstrengthEandmagneticfieldstrengthH,theisophaseplane(thatis,thewavefront)isspherical,cylindricalorplanar.Indifferentsituations,electromagneticwavesaredividedintosphericalwaves,cylindricalwavesandplanewaves.
Transverseelectromagneticwaves,transverseelectricwaves,andtransversemagneticwaves.Electromagneticwaveswhoseelectricandmagneticfieldsareinaplaneperpendiculartothedirectionofpropagationarecalledtransverseelectromagneticwaves,orTEMwavesforshort.Electromagneticwavesthatcontainonlyelectricfieldsonaplaneperpendiculartothedirectionofwavepropagationarecalledtransversewaves,orTEwavesforshort.Electromagneticwavescontainingonlyamagneticfieldonaplaneperpendiculartothedirectionofwavepropagationarecalledtransversemagneticwaves,orTMwavesforshort.
Frequencyrange
Theelectromagneticspectrumisbasedonthewavelengthλorfrequencyfofsinusoidalelectromagneticwavesinfreespace(λf=c=299792458m/s≈3×108m/s)iscalledtheelectromagneticspectrum.Forconvenience,thespectrumisoftendividedintofrequencybandsorbands,asshowninthetable.Above300GHz,itentersthefar-infrared,visiblelight,x-rayandgamma-rayregionsinturn.
Thefrequencyrangeofelectromagneticwavescanbefrominfinityto0Hz(wavelengthisclosetoinfinity,consideringthediameteroftheobservableuniverse,thelowestfrequencyisabout3.4×10-19Hz,Correspondingtoawavelengthofabout93billionlight-years),toaPlanckfrequencyof1.85×1043Hz(wavelengthequalstothePlancklength),wherethefrequencyrangethathumantechnologycandetectis10-2~1035Hz,from10-2Hz(0.01Hz)ofextremelylowfrequency(extremelylongwave,usedingroundpenetratingengineering),To1035Hzofextremelyhighfrequency(veryshortwave,ultra-highenergycosmicrays).Electromagneticwavesaredividedbyfrequencyandwavelength.Thefrequencyfromlowtohigh(wavelengthfromlongtoshort)canbedividedintoradiowaves,microwaves,infraredrays,visiblelight,ultravioletrays,X-raysandgammarays.Theelectromagneticwavesthatthehumaneyecansee——Visiblelightisonlyasmallpartofit.TheinternationalunitofelectromagneticwavefrequencyisHertz(Hz).Commonlyusedfrequencyunitsaremillihertz(mHz,10-3Hz)andkilohertz(kHz,103Hz).),megahertz(MHz,106Hz),gigahertz(GHz,109Hz),terahertz(THz,1012Hz),beatHertz(PHz,1015Hz),Ehertz(EHz,1018Hz),Zehertz(ZHz,1021Hz)andYaohertz(YHz,1024Hz)andsoon.Theelectromagneticwavefrequencyusedinbroadcastingisintheorderof105～108Hz,andtheelectromagneticwavefrequencyusedinTVisintheorderof107～108Hz,theelectromagneticwavefrequencyusedbymobilephonesandwirelessnetworksisintheorderof108～109Hz,theelectromagneticwavefrequencyusedbyopticalfibercommunicationIntheorderof1014Hz.
Calculation
Similartomechanicalwaves(suchassoundwaves,waterwaves,andropewaves)andgravitationalwaves,electromagneticwaveshavewaveproperties.Phenomenasuchasrefractioncanoccur.Itsspeed,wavelength,andfrequencysatisfytherelationship:
Propagationspeed=wavelength×frequency.
Thepropagationspeedofelectromagneticwavesintheairisthespeedoflight,andthewavelengthλ=299.792458/frequencyF(GHz)mm≈300/frequencyF(GHz)mm.Thepropagationtimefromageostationarysatellitetotheearthisabout1/8second.
Formula
c=λf
c:Wavespeed(thespeedoflightisaconstant,equalto299792458m/sinavacuum,approximatelyequalto3×108m/s)Unit:m/s
f:Frequency(Unit:Hz,1MHz=1000kHz=1×106Hz)
λ:wavelength(unit:m)
Thevelocityofelectromagneticwavesinvacuumisc,whichisequaltotheproductofwavelengthλandfrequencyf
Thepropagationspeedofelectromagneticwavesc—about300,000kilometerspersecond,isthefastestspeedofmattermovementintheuniverse.cisaveryimportantconstantinphysics.Thecurrentlyacceptedvalueis:
c=299792.458km/s≈3×108m/s
TheunitofelectromagneticwavefrequencyisalsoHertz(Hz).Butthecommonlyusedunitsarekilohertz(KHz)andmegahertz(MHz).
Energy
Electromagneticwaveshaveenergy.Electromagneticwavesareakindofsubstance,composedofelectricandmagneticfields,buttheyhavenomass.
TheenergyoftheelectromagneticwaveisdeterminedbythePoyntingvector,thatis,S=E×H,whereSisthePoyntingvector,Eistheelectricfieldstrength,andHisthemagneticfieldstrength.E,H,andSareperpendiculartoeachothertoformaright-handedspiralrelationship;thatis,SrepresentsunittimeflowingthroughitTheverticalelectromagneticenergyperunitarea,TheunitisW/m2.
Therelationshipbetweenintensityandamplitude
ElectromagneticwavesarecomposedofelectricfieldcomponentEandmagneticfieldComponentH,thedirectionoftheelectricfieldcomponentandthemagneticfieldcomponentarealwaysperpendiculartoeachother,thephaseisthesame,theelectricfieldcomponentoftheelectromagneticwaveiscalledtheelectricwave,themagneticfieldcomponentiscalledthemagneticwave,butsometimestheelectromagneticwavecanbedirectlyreferredtoastheelectricwave.Forasinglefrequencyelectromagneticwave,itswaveformisasinecurve(cosinecurve),whichiscalledasinewave(cosinewave).Therefore,thesinefunctionisabasictoolforstudyingelectromagneticwaves,whichcangreatlysimplifythecalculationoftheformula.Itcanbeformedbysuperpositionofsinusoidalelectromagneticwavesofdifferentfrequencies.ThecommonmethodtodecomposecomplexelectromagneticwavesintoelectromagneticwavesofdifferentfrequenciesorwavelengthsisFouriertransform.
Theenergyoftheelectricfieldcomponentandthemagneticfieldcomponentisalwaysconvertedtoeachother,sotheenergyofelectromagneticwaves(electromagneticenergy)isactuallycomposedofelectricfieldenergy(electricenergy)andmagneticfieldenergy(magneticenergy),andthetwoenergyisinItisequalatanytimeandishalfofthetotalenergy.Theenergytransferredbyelectromagneticwavesperunittimeiscalledpower.Thederivationofelectricandmagneticenergywithrespecttotimeistheinstantaneouspowerofelectricandmagneticfields.Electricfieldpowerisproportionaltothesquareofelectricfieldstrength,andmagneticfieldpowerisproportionaltothesquareofmagneticfieldstrength.Allofthemconformtothechangeofthesinefunction,exceptthatthefrequencyofchangeistwicethefrequencyoftheelectromagneticwaveitself.Theinstantaneouspoweroftheelectromagneticwaveisthesumoftheinstantaneouspoweroftheelectricfieldandtheinstantaneouspowerofthemagneticfield,anditisalwaystwicetheinstantaneouspoweroftheelectricfieldortheinstantaneouspowerofthemagneticfield.Usuallythepowerisintegratedoveraperiodandaveraged,andthepowerobtainedinthiswayiscalledtheaveragepower.
Themaximumabsolutevaluethattheelectromagneticwave'selectricfieldstrengthEandmagneticfieldstrengthHcanreachiscalledtheelectromagneticwave'smaximumvalueOramplitude,theamplitudeofelectromagneticwavesisdividedintoelectricfieldamplitudeandmagneticfieldamplitude,theunitsareV/mandA/m,bothcanbeItcharacterizestheintensityofelectromagneticwaves,butinpracticalapplications,theintensityofelectricfieldismoreusedastheexpressionmethodofelectromagneticwaveamplitude.Inaddition,therearemethodstoexpresstheamplitudeofelectromagneticwaveswithelectricdisplacement(electricinductionintensity)DandmagneticinductionintensityB,andtheunitsarerespectivelyC/m2andT(ieWb/m2).Thestrengthofelectromagneticwavesischaracterizedby(average)energyflowdensityS(orI,theenergytransmittedperunitareaperunittime),andtheunitisW/m2,thevectorcorrespondingtotheenergyflowdensityiscalledPoyntingvectorS,SisperpendiculartoEandHandformsaright-handedspiralrelationship.ThesizeisEandHTheproductofsize.Theenergyflowdensityisproportionaltothesquareoftheelectricfieldstrengthormagneticfieldstrength,sotheamplitude(electricfieldstrengthandmagneticfieldstrength)canalsobeusedtodescribethestrengthofelectromagneticwaves,butitisproportionaltothesquarerootofitsactualstrength.
Inordertosimplifythecalculation,theelectricfieldstrengthandmagneticfieldstrengthareoftenexpressedbytheDCcomponentstrengthequivalenttotheirpower,whichiscalledtheeffectivevalueoftheelectricfieldcomponentandthemagneticfieldcomponent.TheeffectivevaluesofelectricfieldstrengthandmagneticfieldstrengthErandHrareboth1/√2timesoftheirmaximumvalue(amplitude),namelyEr=E/√2,Hr=H/√2.
RecordtheelectricfieldintensityasE,themagneticfieldintensityasH,theelectricdisplacement(electricinductionintensity)asD,themagneticinductionintensityasB(themaximumvalueisallplusthesubscript0todistinguish),theangularfrequency(2πtimesthefrequency))Isωandtheinitialphaseisφ0,thenthereare:(1),(2),whereεisthepermittivityofthemedium,μisthepermeabilityofthemedium.
Thewavespeedofelectromagneticwaves:
Organize:,namely
Then,(3),(4)
IfZisthecharacteristicimpedanceofthemedium,thenthereis,theunitisΩ.
Then(5),(6)
Soinagivenmedium(εandμareknown),AslongasweknowoneofthefourquantitiesofE,H,D,andB,wecanneutralizetheknownby(1)(2)(3)(4)(5)(6)Thethreeformulasrelatedtothisquantityderivethevaluesoftheotherthreequantities.Inotherwords,inacertainmedium,aslongasoneofthefourquantitiesofE,H,D,andBisdetermined,theotherthreequantitiesareuniquelydetermined.Forexample:whenEisknown,thereare:,,.
Let’sderivetheformulaforcalculatingtheenergyflowdensityoftheconductivemagneticwave:
Theelectricfieldintensitychangefunction:
Themagneticfieldintensitychangefunction：
Theformulaforcalculatingtheinstantaneousenergydensityoftheelectricfield:(εisthedielectricpermittivityofthemedium,thevacuumpermittivityε0=1/(4πc2)×107F/m≈8.854188×10-12F/m)
Theformulaforcalculatingtheinstantaneousenergydensityofthemagneticfield:(μisthepermeabilityofthemedium,thepermeabilityofthevacuumμ0=4π×10-7H/m≈1.256637×10-6H/m)
where
theenergydensityoftheelectromagneticfieldistheenergyoftheelectricfieldandthemagneticfieldThesumofthedensityistheinstantaneousenergydensityoftheelectromagneticfield:
Calculationformulaoftheaverageenergydensityoftheelectricfield:
TheaverageenergydensityofthemagneticfieldCalculationformula:
Averageenergydensityofelectromagneticfield:
MarkasPoyntingvectorTheunitvectorinthedirectionisthePoyntingvector(energyflowdensityvector)oftheelectromagneticwave:(Zisthecharacteristicimpedanceofthemedium,andthevacuumcharacteristicimpedanceZ0=119.9169832πΩ≈376.7303Ω)
Finally,wecangetthe(average)energyflowdensitySoftheelectromagneticwave,thatis,therelationshipbetweentheintensityIandtheamplitude.FirstrecordthemaximumvalueofthePoyntingvectorasS0,thentheaveragevalueoftheenergyflowdensity,andthenrecordtheelectricfieldintensity,magneticfieldintensity,andelectricdisplacement(electricinductionintensity)),theeffectivevaluesofthemagneticinductionintensityareE,H,D,B.Belowwegivetheelectromagneticwaveintensityandelectricfieldintensity,magneticfieldintensity,electricdisplacement(electricinductionintensity),andmagneticinductionintensity(withsubscript0).)Andtherelationshipbetweenfoureffectivevalues(withoutsubscript0):
TherelationshipbetweenelectromagneticwaveenergyflowdensityS(intensityI)andelectricfieldstrengthE:,anditseffectiveValuerelationship:
TherelationshipbetweenelectromagneticwaveenergyflowdensityS(intensityI)andmagneticfieldstrengthH:,anditseffectivevalue:
TherelationshipbetweenelectromagneticwaveenergyflowdensityS(intensityI)andelectricdisplacement(electricinductionintensity)D:,anditseffectivevalue:
TherelationshipbetweenelectromagneticwaveenergyflowdensityS(intensityI)andmagneticinductionintensityB:,anditseffectivevalue:
BecausetheelectricfieldstrengthEisusedtorepresenttheamplitude,therelationshipbetweenthestrengthandtheamplitudecanbemadesimpler(becauseonlyoneparameterisrequired,namelythecharacteristicimpedanceZ,andthecharacteristicimpedanceisanimportantpropertyofthemedium,Thesignificanceisobvious),andtheelectricfieldiseasiertostudythanthemagneticfield.Inaddition,inthevariousphenomenaofelectromagneticwaves,mostoftheelectricfieldcomponentsplayaleadingrole,ratherthanthemagneticfieldcomponents.Theuseofelectricfieldstrengthtodescribetheelectricfieldcomponentsisthemostconcise.Therefore,mostscientistswillusetheelectricfieldstrengthEastherepresentativequantityoftheelectromagneticwaveamplitudetocalculatetherelationshipbetweentheelectromagneticwaveintensityandtheamplitude.Inphysics,withoutanyexplanation,theamplitudeofelectromagneticwavesusuallyreferstotheamplitudeoftheelectricfieldstrengthE.Whenusingtheaboveformulatocalculate,usingtheInternationalSystemofUnitsforcalculation,theamplitudeoftheelectromagneticwave,thatis,theunitoftheelectricfieldstrengthE0(ortheeffectivevalueoftheelectricfieldstrengthE)isV/m,theunitofelectromagneticwaveintensityS(I)isW/m2,theunitofdielectriccharacteristicimpedanceZisΩ.
Example
Question:Theintensityofanelectromagneticwaveinavacuumis,finditselectricfieldintensityamplitude,magneticfieldintensityamplitude,electricdisplacement(electricinductionintensity)Amplitudeandmagneticinductionintensityamplitude.
Solution:Knownelectromagneticwaveintensity,vacuumpermittivity,vacuumpermeability,speedoflightinvacuum.
Vacuumcharacteristicimpedance
Theelectricfieldintensityamplitudeoftheelectromagneticwave
Themagneticfieldintensityamplitudeoftheelectromagneticwave
Electricdisplacement(inductionintensity)amplitudeofelectromagneticwaves
Magneticinductionintensityamplitudeofelectromagneticwaves
Discovery
Theory
In1864,theBritishscientistMaxwellestablishedacompletetheoryofelectromagneticwavesonthebasisofsummarizingpreviousstudiesofelectromagneticphenomena.Heconcludedtheexistenceofelectromagneticwavesanddeducedthatelectromagneticwavesandlighthavethesamepropagationspeed.
Confirmation
In1887,GermanphysicistHertzusedexperimentstoconfirmtheexistenceofelectromagneticwaves.Afterwards,in1898,Marconiconductedmanyexperiments,notonlyprovedthatlightisanelectromagneticwave,butalsodiscoveredmoreformsofelectromagneticwaves,theiressenceisexactlythesame,butthewavelengthandfrequencyareverydifferent.
Generation
Electromagneticwavesareaformofmotionofelectromagneticfields.Electricityandmagnetismcanbesaidtobetwosidesofonebody.Achangingelectricfieldwillproduceamagneticfield(thatis,anelectriccurrentwillproduceamagneticfield),andachangingmagneticfieldwillproduceanelectricfield.Thechangingelectricfieldandthechangingmagneticfieldformaninseparableunifiedfield,whichistheelectromagneticfield,andthepropagationofthechangingelectromagneticfieldinspaceformselectromagneticwaves.Thechangesinelectromagneticarelikewaterwavesgeneratedbyabreezeblowingonthewatersurface,soitiscalledElectromagneticwaves,alsooftencalledelectricwaves.
ElectromagneticwaveswerefirstpredictedbyJamesMaxwellin1865,andthenconfirmedbyGermanphysicistHeinrichHertzinexperimentsfrom1887to1888.Maxwelldeducedtheelectromagneticwaveequation,awaveequation,whichclearlyshowsthewavenatureofelectricandmagneticfields.Becausetheelectromagneticwavevelocitypredictedbytheelectromagneticwaveequationisequaltothemeasuredvalueofthespeedoflight,Maxwelldeducedthatlightwavesarealsoelectromagneticwaves.
Properties
Whenthecurrentfrequencyislow,theelectromagneticwavecanbeemittedandtransmittedmainlythroughtangibleconductors.Thereasonisthatinlow-frequencyelectricaloscillations,themutualchangebetweenmagnetoelectricityisrelativelyslow,andalmostallofitsenergyreturnstotheoriginalcircuitwithoutenergyradiation;whenthecurrentfrequencyishigh,itcanbetransmittedinthefreespaceintheformofelectromagneticwaves,oritcanbebound.Transmittedinatangibleconductivebody.Thereasonforthetransmissioninfreespaceisthatinthehighfrequencyelectricoscillation,themagnetoelectricmutualchangeisveryfast,anditisimpossibleforalltheenergytoreturntotheoriginaloscillationcircuit,sotheelectricandmagneticenergyaretransmittedtothespaceintheformofelectromagneticwaveswiththeperiodicchangesoftheelectricfieldandthemagneticfield.Ifitspreadsout,energycanbetransferredoutsidewithoutamedium.Thisisakindofradiation.Forexample,thedistancebetweenthesunandtheearthisverylong,butwecanstillfeelthelightandheatofthewarmsunlightwhenoutdoors,whichisliketheprincipleof"electromagneticradiationtransfersenergythroughradiationphenomena".
Electromagneticwavescanbeblockedandreflectedbymetalmaterials.ThemetalplatecanblockandreflectelectromagneticwaveswithafrequencylowerthanX-rays.WhenthefrequencyisgreaterthanorequaltoX-rays,theelectromagneticwaveshavehigherenergyandwillpenetratedirectly.Metalmeshcanalsoblockandreflectelectromagneticwaves,butitcanonlytargetelectromagneticwaveswithlongerwavelengths.Forelectromagneticwaveswithlongerwavelengths,whentheapertureofthemetalmeshislessthan1/4ofthewavelength(disforelectromagneticwaveswithshorterwavelengthsbutwithafrequencynotgreaterthanultraviolet(theshorterwavelengthherereferstothefartherwavelengthscale).Muchsmallerthantheporesizeoftheobject,generallyatthemicronlevelorbelow),suchasinfrared,visiblelightandultravioletlight.Atthistime,electromagneticwavescanpassthroughthemesh(thesizeofthemeshislargerthanthewavelength),butitwillstillbeblockedandreflectedbythemetalplateThisexplainswhyallmetalmaterialscanstronglyreflectvisiblelight.Thisisalsothefundamentalreasonwhymetalmaterialshaveluster.Forexample,lightcanpassthroughbarbedwirebutnotthroughironplates.Inaddition,ironplateshaveexcellentlightreflectingability.Forelectromagneticwaveswithshorterwavelengths,theycannotbeblockedbymetalplates,suchasX-raysandgammarays.Asaresult,itspenetratingpowerisextremelystrong,soitcanignoremetalmaterialsanddirectlypenetratethepast.
Electromagneticwavesareshearwaves.Themagneticfield,electricfield,andThethreedirectionsoftravelareperpendiculartoeachother.Theamplitudealternatesperiodicallyalongtheverticaldirectionofthepropagationdirection,anditsintensityisinverselyproportionaltothesquareofthedistance.Thewaveitselfdrivesenergy,andtheenergypoweratanypositionisproportionaltothesquareoftheamplitude.Itsspeedisequaltothespeedoflight.c(299792458m/s≈3×108m/s).Theelectromagneticwavepropagatinginspacehasthesameintensitydirectionasthenearestelectricfield(magneticfield),andthemaximummagnitudeisthedistancebetweentwopoints,Itisthewavelengthλoftheelectromagneticwave,andthenumberofelectromagneticchangespersecondisthefrequencyf.Therelationshipbetweenthethreecanbeobtainedbytheformulac=λf.
ThepropagationofelectromagneticwavesdoesnotrequireamediumElectromagneticwavesofthesamefrequencyhavedifferentspeedsindifferentmedia.Whenelectromagneticwavesofdifferentfrequenciespropagateinthesamemedium,thegreaterthefrequency,thegreatertherefractiveindexandthelowerthespeed.Electromagneticwavescanonlybeinthesamehomogeneousmedium.Propagationalongastraightline,ifthesamemediumisnotuniform,therefractiveindexoftheelectromagneticwaveinitisdifferent.Insuchamedium,ittravelsalongacurve.Whenpassingthroughdifferentmedia,refraction,reflection,diffraction,scattering,andAbsorption,etc.Thepropagationofelectromagneticwavesincludesgroundwavesthatpropagatealongtheground,airwavesandskywavesthatpropagatefromtheair.Thelongerthewavelength,thelessattenuation,andthelongerthewavelengthofelectromagneticwaves,theeasieritistobypassobstaclesandcontinuetopropagate.Mechanicalwaves,electromagneticwaves,andgravitationalwavescanberefracted,reflected,diffracted,andinterfered,becauseallwaveshavewaveproperties.Diffraction,refraction,reflection,andinterferenceareallwaveproperties.
ElectromagneticwavesTheelectricfield(ormagneticfield)changeswithtimeandhasperiodicity.Thedistancetraveledinanoscillationcycleiscalledthewavelength.Thereciprocaloftheoscillationcycle,thatis,thenumberofvibrations(changes)persecond,iscalledthefrequency.
Theproductofwavelengthandfrequencyisthedistancetraveledpersecond,thatis,thespeedofthewave.Letthewavelengthbeλ,thefrequencyisf,andthespeedisV,so:λ=V/fTheunitofwavelengthismeters(m),andthespeedTheunitisMeterspersecond(m/sec),theunitoffrequencyisHertz(Hertz,Hz).Theentireelectromagneticspectrumincludesacollectionofvariouswaves,lights,andraysfromextremelylowfrequencyradiowavestoextremelyhighfrequencygammacosmicrays.Thedifferentfrequencyparagraphsarenamedasextremelylongwaveelectromagneticwaves(radiowavesbelow3KHz),radiowaves(3KHz-300GHz),infrared,visiblelight,ultravioletrays,X-rays,gammarays(gammarays)andcosmicrays(ultra-highenergygammarays).).
Electromagneticspectrum
Arrangetheseelectromagneticwavesintheorderofwavelengthorfrequency,whichistheelectromagneticspectrum.Ifthefrequencyofeachbandisarrangedfromlowtohigh,theyarepowerfrequencyelectromagneticwaves,radiowaves(dividedintolongwave,mediumwave,shortwave,microwave),infrared,visiblelight,ultraviolet,X-rayandgammarays.Radiohasthelongestwavelength,andcosmicrays(x-rays,gammarays,andshorter-wavelengthrays)havetheshortestwavelengths.
Firstofall,radiowavesareusedforcommunications,microwavesareusedformicrowaveovens,infraredisusedforremotecontrol,thermalimagingcameras,infraredguidedmissiles,etc.Visiblelightisthebasisformostorganismstoobservethings,andultravioletlightisusedforMedicaldisinfection,verificationofcounterfeitbanknotes,distancemeasurement,engineeringflawdetection,etc.X-raysareusedforCTphotography,andgammaraysareusedfortreatmenttocauseatomstoundergotransitionstogeneratenewrays.
Radiowave1mm~3000m(microwave1mm~1m)
Infrared0.76micron~1mm(where:nearinfraredshortwaveis0.76~1.1micron,nearinfraredlongwave1.1to2.5microns,mid-infraredis2.5-6microns,far-infraredis6-15microns,ultra-far-infraredis15micronsto1mm)
Visiblelight0.38micronsto0.76microns
Ultravioletrays10nm～0.38μm
X-ray1picometer～10nm
γ-ray0.1picometer～1picometer
Highenergyradiationislessthan1Picometer
Thewavelengthusedbyfax(TV)is3-6meters
Thewavelengthusedbyradaris3meterstoseveralmillimeters.
Englishabbreviationofelectromagneticradiationclassification:
γ=gammaray
X-ray:
HX=hardX-ray
SX=softX-ray
Ultraviolet:
EUV=extremeultraviolet
NUV=nearultraviolet
p>Infrared:
NIR=NearInfrared
MIR=MidInfrared
FIR=FarInfrared
Microwave:
EHF=veryhighfrequency
SHF=ultrahighfrequency
UHF=veryhighfrequency
radiowave:
VHF=veryhighfrequency
HF=highfrequency
MF=intermediatefrequency
LF=lowfrequency
VLF=verylowfrequency
ULF=UltraLowFrequency
ELF=ExtremeLowFrequency
Nameofelectromagneticwave | Frequencyrange | Wavelengthrange | PhotonEnergyrange | Periodrange | |||||
(Thelowestfrequencyelectromagneticwavethatmayexist) | 3.4×10-19Hz | 8.8×1026m | 1.4×10-33eV | 2.9×1018s | |||||
Radiowave | <300MHz | >1m | <1.24μeV | >3.33ns | |||||
Microwave | 300MHz~300GHz | 1mm~1m | 1.24μeV~1.24meV | 3.33ps~3.33ns | |||||
Infrared | 300GHz~400THz | 750nm~1mm | 1.24meV~1.65eV td> | 2.5fs~3.33ps | |||||
Visiblelight | Redlight | 400THz~750THz | 400THz~480THz | 400nm~750nm | 620nm~750nm | 1.65eV~3.1eV | 1.65eV~2eV | 1.33fs~2.5fs | 2.07fs~2.5fs |
Orangelight | 480THz~505THz | 595nm~620nm | 2eV~2.09eV | 1.98fs~2.07fs | |||||
Yellowlight | 505THz~520THz | p>575nm~595nm | 2.09eV~2.16eV | 1.92fs~1.98fs | |||||
Greenlight | 520THz~600THz | 500nm~575nm | 2.16eV~2.48eV | 1.67fs~1.92fs | |||||
Blu-ray | 600THz~700THz | p>430nm~500nm | 2.48eV~2.89eV | 1.43fs~1.67fs | |||||
Purplelight | 700THz~750THz | 400nm~430nm | 2.89eV~3.1eV | p>1.33fs~1.43fs | |||||
Ultraviolet | 750THz~30PHz | 10nm~400nm | 3.1eV~124eV | 33.3as~1.33fs | |||||
X-ray | 30PHz~30EHz | 10pm~10nm | 124~124keV | 33.3zs~33.3as | |||||
GammaRay | >30EHz | <10pm | >124keV | <33.3zs | |||||
(thehighestfrequencyelectromagneticwavethatmayexist) | 1.85×1043Hz | 1.62×10-35m | 7.67×1028eV | 5.39×10-44s |
Radiospectrum
Attheendofthe19thcentury,theItalianMarconiandtheRussianPopovconductedradiocommunicationexperimentsin1895..Inthenext100years,thespectrumfrom3KHzto300GHzwasrecognized,developedandgraduallyutilized.Withthedevelopmentoftechnology,extremelylong-waveelectromagneticwavesbelow3KHzcanalreadybegenerated,andopticalbands(infrared)above300GHzcanalsobegraduallygeneratedbyelectronicoscillationtechnology,insteadofjuststayinginquantumtransitions(suchaslasers).Atalevel,thefrequencyofelectromagneticwavesgeneratedbyelectronictechnologycanexceed1000GHz(1THz),andthehighestcanevenreachtensofthousandsofGHz(tensofTHz).
Accordingtodifferentpropagationcharacteristicsanddifferentservices,theentireradiospectrumisdividedinto13sections:tolowfrequency,extremelylowfrequency(ELF),ultralowfrequency(SLF),andultralowfrequency(ULF),VLF,LF,MF,HF,VHF,UHF,SHF,EHFAndtohighfrequency,plusJimmywaveandHumiwave,thecorrespondingwavebandsarefromJimmywave,tolongwave(100megameterwave),extremelylongwave(10megameterwave),ultralongwave(megameterwave),extralongwave(Onehundredthousandmeterwave),verylongwave(tenthousandmeterwave),longwave(kilometerwave),mediumwave(100meterwave),shortwave(tenmeterwave),veryshortwave(meterwave),veryshortwave(decimeterwave),Ultrashortwave(centimeterwave),veryshortwave(millimeterwave),toshortwave(silmiwave)andHumiwave(fromdecimeterwavetomillimeterwavethreekindsarecollectivelycalledmicrowave).Seethetablebelow.
Segmentnumber | frequencybandname | frequencybandrange(includingupperlimitbutnotlowerlimit) | Bandname1 | Bandname2 | Wavelengthrange(includingthelowerlimitbutnottheupperlimit) | Remarks |
-1 | 0.03～0.3Hz | JimiBo | 10～1Gm | / | ||
0 | tolowfrequency | 0.3～3Hz | tolongwave | Onehundredmegameterwave | 1000～100Mm | / |
1 | Extremelylowfrequency | 3～30Hz | Extremelylongwave | Tenmegameterwave | 100～10Mm | / |
2 | Ultralowfrequency | 30～300Hz | Ultra-longwave | Megameterwave | 10～1Mm | / |
3 | Ultralowfrequency | 300～3000Hz | Speciallongwave | Onehundredthousandmeterwave | 1000～100km | / |
4 | VeryLowfrequency | 3～30kHz | Verylongwave | 10,000meterswave | 100～10km | / |
5 | Lowfrequency | 30～300Kilohertz | longwave | Kilometerwave | 10～1km | / |
6 | Intermediatefrequency | 300～3000kHz | Mediumwave | Onehundredmeterwave | 1000～100m | / |
7 | Highfrequency | 3～30MHz | Shortwave | Ten-meterwave | 100～10m | / |
8 | VHF | 30～300MHz | Veryshortwave | MiBo | 10～1m | / |
9 | UHF | 300～3000MHz | Ultrashortwave | decimeterwave | 10～1dm | microwave |
10 | UHF | 3～30GHz | Ultrashortwave | cmwave | 10～1cm | |
11 | veryhighfrequency | 30～300GHz | Ultrashortwave | millimeterwave | 10～1mm | |
12 | Tohighfrequency | 300～3000GHz | Toshortwave | SimiBo | 1～0.1mm | / |
13 | 3000～30000GHz | MiBo | 0.1～0.01mm | / |
Thepenetrationofelectromagneticwaves
BecauseelectromagneticwaveshavetwowavesImageproperty,thewavelengthisinverselyproportionaltothephotonenergy.Theshorterthewavelength,thegreaterthephotonenergy,thestrongerthepenetratingpower.Forexample,high-energyX-rayscanpenetratealmostallnon-metallicobjects,eventhinaluminum;whilegammarayscanpenetratemostmetals.Certainheavymetalscanblockthepenetrationofelectromagneticwaves,suchaslead.Forelectromagneticwaveswithlongerwavelengthsandlowerenergy,penetratingpowergenerallyreferstodiffractionability.Atthistime,thelongerthewavelength,thestrongerthepenetratingpower.Forexample,2.4GWi-Fisignalpenetrationisbetterthan5GWi-Fi.Thesignalisstrong.
Application
Radiowaveforcommunication,etc.
Microwaveformicrowaveoven,satellitecommunication,etc.
Infraredraysareusedforremotecontrol,thermalimagingcameras,infraredguidedmissiles,etc.
VisiblelightisusedbyalllivingthingstoobservethingsBasic
Ultravioletraysformedicaldisinfection,verificationofcounterfeitbanknotes,distancemeasurement,engineeringflawdetection,etc.
X-rayUsedinCTphotography
Gammaraysareusedfortreatment,whichcausesatomstoundergotransitionstogeneratenewrays,etc.
Radiocommunication
Bothradiobroadcastingandtelevisionuseelectromagneticwaves.Inradiobroadcasting,peoplefirstconvertacousticsignals(mechanicalwavesignals)intoelectricalsignals,andthenthesesignalsarecarriedbyhigh-frequencyoscillatingelectromagneticwavestothesurroundingspace.Atanotherplace,peopleusethereceivertoreceivetheseelectromagneticwaves,andthenrestoretheelectricalsignalsintoacousticsignals.Thisisthegeneralprocessofwirelessbroadcasting.InTV,exceptfortheprocessingofacousticsignalsasinwirelessbroadcasting.,Itisnecessarytoconverttheopticalsignaloftheimageintoanelectricalsignal,andthenthetwosignalsarealsocarriedbythehigh-frequencyoscillatingelectromagneticwavetothesurroundingspace,andthetelevisionreceiverreceivestheseelectromagneticwavesandthentransferstheelectricalsignal.Itisrestoredintosoundsignalandlightsignal,therebydisplayingthepictureoftheTVandthesoundinthespeaker.
Thefrequencyofelectromagneticwavesusedinradiobroadcastingisveryhigh,andtherangeisalsoverylarge,whilethefrequencyofelectromagneticwavesusedinTVishigherandtherangeislarger.
Medical
TDP
"Specificelectromagneticspectrum"(TDP)isthewavelengthrangeof2-25μmgeneratedbyaspecificheateronthetreatmentplate.Thespecificelectromagneticwavesdistributedwithintherange(28-35mw/cm2)willresonatewiththesamesubstancescontainedinthecellsinthebodywhenthebodyismatchedandreceived,therebyenhancingthemicrocirculationeffect,promotingmetabolism,andrepairinghumanbodylesions,sothatpatientscanbeRapidrecovery,non-illpatientscanimprovetheirownresistance.
Examples
Forexample,GuorenTDP,basedonalargenumberofclinicaltrials,confirmedthatspecificelectromagneticspectrumirradiationcanbeusedtotreatcervicalspondylosis,lumbardischerniation,lowbackpain,andlowbackhungerStrain,rheumatoidarthritis,sciatica,facialnervepalsy,postoperativewoundhealing,traumainfection,frostbite,gastritis,diaphragmspasm,neurodermatitis,eczema,migraine,headache,dysmenorrhea,hemorrhoids,etc.Itiswidelyusedinsurgery,internalmedicine,gynecology,pediatrics,neurologyandotherdiseases.Atthesametime,ithasbeenaccuratelymeasuredbyauthoritativeinstitutionssuchastheNationalAcademyofMetrologyandconfirmedthatithasnosideeffectsonthehumanbody.
Others
Inaddition,electromagneticwavesarealsousedinmobilephonecommunications,satellitesignals,navigation,remotecontrol,positioning,homeappliances(microwaveovens,inductioncookers)infraredwaves,industrial,medicalequipment,etc.
Electromagneticradiation
Definition
Generalizedelectromagneticradiationusuallyreferstotheelectromagneticspectrum,includingradiowaves,visiblelight,gammaraysandotherelectromagneticwaves.Inanarrowsense,electromagneticradiationreferstotheradiationwavesgeneratedbyelectricalequipment.Thewavelengthoftheseradiationwavesisusuallybelowtheinfrared(longerwavelength).
Types
Electromagneticradiationisawaytotransferenergy.Therearethreetypesofradiation:
Ionizingradiation
YesNon-ionizingradiationwithoutthermaleffect
Non-ionizingradiationwithoutthermaleffect
Basestationelectromagneticwavesareneverionizingradiationwaves
Humaninjury
Mainmechanism
Themechanismofelectromagneticradiationharmingthehumanbodyismainlythermaleffect,non-thermaleffectandaccumulationeffect.
Thermaleffect
Thehumanbodyisaconductor.Likeallconductors,afterthehumanbodyisexposedtowirelesscurrentandmicrowaveradiation,itgeneratescurrent,whichcausesthehumanbodytoheatup.Generallyspeaking,theradiowavesandmicrowavesinthespaceweliveinarerelativelyweak,andtheheatgeneratedisverysmallandcanbecompletelyignored.
Theinfraredandvisiblelightemittedbythesunisthestrongestelectromagneticradiationinnature,anditisalsothestrongestsourceofelectromagneticradiationinourenvironment.Infraredandvisiblelightcancauseheatonthesurfaceofthehumanbody.
Non-thermaleffect
Thehumanbody’sorgansandtissuesallhaveweakelectromagneticfields.Theyarestableandorderly.Onceexposedtocertainfrequencyelectromagneticwavesfromtheoutsideworld,Interference,theweakelectromagneticfieldinabalancedstatemaybedestroyed,whichwillaffectthefunctionofthehumanbody.
Whichfrequenciesofelectromagneticwavescanproduceinterference,andhowmuchimpacttheseinterferenceshaveonthehumanbody,requirefurtherresearch.
Cumulativeeffect
Inadditiontoradiatinginfraredandvisiblelight,thesunalsoradiatesalotofhigh-energyultravioletrays,whicharealsobeneficialtothehumanbodyYes,buttoostrongultravioletrayscanburntheskinandmayinduceskincancer.
X-raysandgammaraysarehigh-energyelectromagneticradiation,whichcandirectlydestroythemolecularstructureofthehumanbody,includingthestructureofproteins,DNA,etc.,therebycausingdiseaseinthehumanbodyandcausingvariouscancers.
Ifthehumanbodyisdamagedbyhigh-energyelectromagneticradiationbeforeithastimetorepairitself,thedamagewillaccumulate,anditwillbecomeapermanentillnessorlife-threatening.Forgroupswhohavebeenexposedtohigh-energyelectromagneticradiationforalongtime,evenifthepowerislowandthefrequencyislow,itmayinduceunexpectedlesions.Youshouldbevigilant!
Somescientistshaveprovedthroughlong-termresearchthatlong-termexposuretoelectromagneticradiationcancausehumanimmunity,metabolicdisorders,memoryloss,prematureaging,arrhythmia,visionloss,hearingloss,abnormalbloodpressure,andskinacne.,Roughness,andevenleadtovarioustypesofcancer,etc.;maleandfemalereproductiveabilitydeclines,womenarepronetomenstrualdisorders,miscarriage,teratogenesisandotherdiseases.However,thereisnoexperimentalproofforthetimebeing,andnolarge-scalestatisticstoprovethatthereisaninevitableconnection
Foodswithanti-electromagneticwaveradiationhazardsinclude:greentea,kelp,seaweed,seaweed,Va,Vc,Vb1.EggsHigh-qualityanimalproteinsuchasphospholipids,pigblood,milk,turtle,crab,etc.
Performance
1,CentralNervousSystemHarm
Thenervoussystemisverysensitivetotheeffectsofelectromagneticradiation.Afterrepeatedlow-intensityeffects,thefunctionofthecentralnervoussystemchangesandneurastheniasyndromeappears.Themainmanifestationsareheadache,dizziness,weakness,memoryloss,andsleepdisorders(insomnia,dreams)Ordrowsiness),daytimedozingoff,irritability,hyperhidrosis,heartpalpitations,chesttightness,hairloss,etc.,especiallydifficultyfallingasleep,weakness,hyperhidrosisandmemorylossaremoreprominent.Theseallindicatethatthebrainistheinhibitoryprocessdominated,sothevictimInadditiontotheabovesymptoms,short-termmemoryloss,visualmotorresponsetimeisclearlyprolonged,poorhand-braincoordination,slowingdownthespeedofmarkingnumbers,andmoreerrors.
2.Harmtotheimmunefunctionofthebody
Decreasedbodyresistance,animalexperimentsandresearchandinvestigationsontheeffectsofradiationonthepopulationshowthatthepercentageofhumanleukocytesphagocytosingbacteriaandThenumberofphagocyticbacteriadecreased.Inaddition,peoplewhowereexposedtolong-termelectromagneticradiationhadsignificantlyinhibitedtheformationofantibodies.
3.Impactonthecardiovascularsystem
Peoplewhoareexposedtoelectromagneticradiationoftensufferfromhemodynamicdisorders,decreasedvascularpermeabilityandtension,andduetotheinfluenceofautonomicnerveregulation,mostpeoplehavesymptomsofbradycardia,andafewhavetachycardiaandvictims.Bloodpressurefluctuates,beginstorise,andthenreturnstonormal,andfinallylowbloodpressure;thevoltageofRTwaveonECGdrops,whichistheallergicreactionofthevagusnerveandtheresultofmyocardialdystrophy;theprolongationbetweenPandQ,thePwaveWidened,indicatingthattheatrioventricularconductionispoor.Inaddition,peoplewhohavebeenexposedtoelectromagneticradiationforalongtimewillhavecardiovasculardiseasesearlierandeasiertopromotetheiroccurrenceanddevelopment.
4.Influenceofthesystem
Undertheactionofelectromagneticradiation,whitebloodcellsmaybeunstableintheperipheralbloodimage,mainlyduetoadownwardtrend.Theresultsofahealthsurveyofpeoplewhomanipulateradarsshowthatmostpeoplehavereducedwhitebloodcells.Inaddition,whenradiowavesandradiationactonthehumanbodyatthesametime,theeffectonthebloodsystemcancausemoreobviousdamagethanasinglefactor.
5.Effectsonthereproductivesystemandheredity
Peoplewhohavebeenexposedtoultrashortwavegeneratorsforalongtimemayexperiencedecreasedsexualfunctioninmen,impotence,andmenstrualcycledisordersinwomen.Duetothepoorbloodcirculationofthetesticles,itisverysensitivetoelectromagneticradiation,spermproductionisinhibitedandaffectsfertility;itmakestheeggcellsdegenerate,destroystheovulationprocess,andmakeswomenlosetheirfertility.
High-intensityelectromagneticradiationcanproducegeneticeffects,causingaberrationsintesticularchromosomesandabnormalmitosis.Pregnantwomenreceiveshort-wavediathermyatanearlystageorbeforepregnancy.Asaresult,theiroffspringappearcongenitalBirthdefects(deformedbabies),
6.Influenceonthevisualsystem
Theeyetissuecontainsalotofwater,whicheasilyabsorbselectromagneticradiationpower,andThebloodflowoftheeyeislow,soundertheactionofelectromagneticradiation,thetemperatureoftheeyeballiseasytorise,andthetemperatureriseisthemainconditionthatcausescataracts.Theriseintemperatureleadstothecoagulationofthelensproteinoftherose,andthevisiblelightandultravioletraysdonotdamagethehumaneyes.Itgoeswithoutsayingthat,inaddition,mostscholarsbelievethatthelong-termeffectsoflow-intensitymicrowavescanacceleratetheagingandturbidityofthelens,causethevisiontoturnyellow,andmayreducethecoloredfieldofvisionandprolongthedarkadaptationtime,causingsomevisualdisturbances,Inaddition,theeffectoflong-termlow-intensityelectromagneticradiationcanpromotevisualfatigue,eyediscomfortanddryeyes.
7.Carcinogenicandcarcinogeniceffectsofelectromagneticradiationp>
Mostexperimentalanimalscanincreasetheincidenceofcanceraftermicrowaveaction.ExperimentsbysomemicrowavebiologistshaveshownthatelectromagneticradiationcancausemutationsandMitosisisabnormal,whichcausespathologicalproliferationincertaintissues,whichturnsnormalcellsintocancercells.ThestaffofaUSembassyabroadhasbeenexposedtothehighelectromagneticradiationemittedbymicrowaveeavesdroppingforalongtime,causingthenumberofwhitebloodcellsoftheembassystafftoincrease.Theincidenceofcancerishigherthanthatofnormalpeople,andtheareaundertheinfluenceofhigh-powerlong-rangemicrowaveradarhasbeeninvestigated.Therapidincreaseinlocalcancerpatientsandtheheatingeffectofmicrowaveonhumantissuescanbeusednotonlyforphysicaltherapy,butalsofortreatmentCancerraisesthecentertemperatureofcancertissuesanddestroystheproliferationofcancercells.Inadditiontothehealthhazardsofelectromagneticradiationmentionedabove,italsoaffectstheendocrinesystem,vision,hearing,materialmetabolism,tissuesandorgans.Changesintheshapeofthewormscanhaveadverseeffects.
Recognizethehazards
Inasafeelectromagneticenvironment,ifyouimaginethatelectromagneticwaveswilldamageyourhealthforalongtime,youwillinevitablycauseanxiety,fear,anddepressionduetoexcessivementalstress.Andotherpsychologicalproblems,andthenaffecttheendocrine,andevenaffecttheirownhealth.Therefore,itisnecessarytocorrectlyunderstandthecausesofelectromagneticwavesandthepossibleharms,andtomasterhowtoreduceoravoidtheinfluenceofelectromagneticwavesthatarecommoninlife.
Aslongasitisnotatabsolutezero(273.15degreesCelsiusbelowthetemperaturescale),allobjectswillradiateelectromagneticwavestotheoutsideworld.Absolutezeroisimpossibletoachieveinnature,soelectromagneticwavesareeverywhere.Therefore,electromagneticwaves(theenergylevelofelectromagneticwavesdoesnotexceedthelimitofthecorrespondingfrequency)inordinaryenvironmentswillnotharmourhealth,butlong-termexposuretohigh-levelelectromagneticwaves(theenergylevelofelectromagneticwavesexceedsthelimitofthecorrespondingfrequency)willcauseCausedamagetoourhealth.
Theelectromagneticradiationexceedingstandardalarm(withacertainfrequencyresponserange)canmeasuretheintensityofelectromagneticwavesinacertainfrequencyrange.Aslongastheelectromagneticradiationintensitystandardspecifiedbythefrequencyisexceeded,awarningsignalwillbeissued,andtheuserwillKeepawayfromtheobjecttobemeasureduntilthewarningdisappears(thedistancebetweenthedisappearingpositionofthewarningandtheelectromagneticwavetransmittingfacilityequipmentcanberegardedasasafedistance).[Relyontheinfluenceofelectromagneticwavesfromshieldingfacilities).Relyingonthethreeprinciplescaneffectivelyreduceoravoidtheinfluenceofelectromagneticwavesthatarecommoninlife.
Electricalappliancescommonlyusedinthehomealsohavedifferentprecautions.Atpresent,mainstreamTVsandcomputermonitorshavealladoptedtheelectromagneticwavesgeneratedbytheliquidcrystaldisplayitself,exceptforvisiblelight.Theenergylevelisverylow,andithasbeenkeptatacertaindistancefromthehumanbodywheninuse.Setasafetydistanceofatleast1to2meters.Mobilephonesarecurrentlycommonlyusedequipmentinourlives.Whenmakingandansweringmobilephones,theyshouldbeheldinthehandorplacedatadistanceof50cmfromthehumanbody.Hands-freeansweringshouldbeusedasmuchaspossible.Inductioncookersandmicrowaveovensshouldbeasfarawayaspossible(atleastmorethan1meter)whentheystarttousethem.Aftertheheatingiscompleted,theelectricblanketshouldbeturnedoffbeforegoingtobed.Donotstayontheelectricblanketthatisturnedonforalongtime.Atpresent,thecommonlyusedWIFIdevicecanbemorethan1meterawayfromthehumanbodywhenitisturnedon.Duetotheworkingprincipleoftheradio,itonlyreceivesusefulelectromagneticwaves,anddoesnotemitusefulelectromagneticwaves,andtheelectromagneticwaveenergylevelgeneratedbyitsownoriginalsandcircuitsisverysmall,sothereisnoneedtosetaspecialsafetydistance.Smallelectricalappliancessuchashairdryersrelyonmotorstooperate,andthereisnoneedtosetaspecialsafetydistancebecauseoftheirshortusetime.Forelectricheatingappliances(suchasheaters)usedincoldweather,asafeusedistanceof0.5metersormoreshouldbesettoavoidburnsandelectromagneticradiation.
Buyingahouseisonthesidefarawayfromtheinletandoutletofoutdoorhigh-voltagesubstations(exceptsubstationswithvoltagelevelsof35kVandbelow;excludingindoorsubstationsandundergroundsubstations),high-voltageoverheadlines(withvoltagelevelsof35kVandbelow)Exceptforoverheadlines;exceptforundergroundcables),towerswhoseantennapolarizationisverticalpolarizationandmainlyrelyongroundwavepropagation(suchasmediumwavestations),orradioandtelevisiontowerswitharelativelysmallheightdifferencefromthebuilding(higherthanthebuilding).Thereisasignalblindzonebelowtheradioandtelevisiontowerwithabigdifference).
Toreducetheadverseeffectsofelectromagneticwaves,itisnecessarytodevelopthehabitofself-prevention.Generalelectricalappliancesstoressell"electromagneticwavetestpens",whichcaneasilymeasuretheintensityofelectromagneticwaves.Aslongasitexceedsthestandard,awarningwillbeissued.Usersshouldstayawayfromtheobjectundertestuntilthewarningdisappears.
Totestwhetherelectricalproductshaveradiationorelectromagneticwaves,youcanalsotakearelativelysimpleway,thatis,useahome,smallradiothatcanreceiveAM(AmplitudeModulation)channels,andturnonthechanneltoadjustthechanneltoanon-broadcastedradio.Ifyoufindthatthevolumeoftheradiosuddenlyincreases,itmeansthatthereisstrongelectromagneticradiationaroundtheappliance.Aftergoingoutforacertaindistance,thevolumewillreturntoitsoriginallowstate;inthisway,the"safe"distancecanbemeasured.
Differentelectricalappliancesalsohavedifferentprecautions.Forexample,whenacomputerisused,itisbesttoonlyturnoffthescreenwithoutshuttingitdown.ThecomputerscreenshouldbereplacedwithanLCDscreen;whenansweringamobilephone,itisbestnottoputthemobilephoneonyourwaist.Occasionally,inthepocketoftrousers,itshouldbeheldinthehandorplacedatadistanceof50cmfromthehumanbody;thepurchaseofahouseshouldbefarawayfromtheinstallationlocationofthesubstationequipmentandthebasestation.
In1993,asurveyofthethreeNordiccountriesinSwedenannouncedthatundertheinfluenceofelectromagneticradiationabove2mG,thechanceofsufferingfromleukemiais2.1timesthatofnormalpeople,andthechanceofsufferingfrombraintumorsis1.5timesthatofnormalpeople.TheaboveinformationistakenfromSAPIOmagazinewaspublishedinJapaninMarch1996.
Usingacomputerradiationeliminator
Thecomputerradiationeliminatorusesthemethodofelectronicshieldingwaveformshaping,oscillationinterference,exportandabsorptionthroughthepowersupply;makethecomputerandTheACpoweroftheaccessoryequipmentreachesanearidealstate.Itcandynamicallyfindandtracktheradiationgeneratedbythecomputermotherboard,CPU,harddisk,monitor,keyboard,mouse,andequipmentconnectedtothecomputer,whichisabsorbedandconvertedbythesmartchipmoduleinsidetheproduct.,Eliminate,effectivelyeliminatetherootcauseoftheinvisiblekillerthataffectsourhealth-computerradiation!
ExpertSuggestions
10measurestopreventelectromagneticwaves | Reasonexplanation |
1.Trytostayawayfromelectrochemicalproducts | Thelongerthedistance,thesmallertheintensityofelectromagneticwaves,andthelessharmfulitwillbetothehumanbody. |
2.Shortentheusetimeasmuchaspossiblewhenyoucannotstayaway | Thestrongertheelectromagneticwave,theshorterthetime,thesmallertheimpact. |
3.Chooseproductswithlowelectromagneticradiation | Lightbulbsaresmallerthanfluorescentlamps,energy-savinglampsarelarger,LEDlampsaresmaller,andfixedphonesaresmallerthanwirelessphones. |
4.Insteadofchoosingalargeone,trytochooseasmallone | Thelarge-scalehomeappliancesofthesamekindnotonlyconsumehighpower,butalsohavestrongelectromagneticwaves. |
5.Youngpeopleshouldpayspecialattention | Youngpeoplewhosecelldivisionisvigorousareeasilyaffected.Pregnantwomenshouldpayspecialattentiontoit. |
6.Thesafetydistancemustbeclearlymeasured | Themanufacturer'sdatawillnotbetooaccurate,soitshouldbeclearlymeasured. |
7.Payattentiontotherearandbothsides | TheelectromagneticwavesemittedfromtherearandbothsidesofLCDTVsandpersonalcomputersarerelativelystrong. |
8.Unplugtheplugwhennotinuse | Whentheplugispluggedin,mostoftheelectromagneticwaveswillbereleased. |
9.Payspecialattentionwhensleeping | Sleeptimeisusuallyverylong,donotexposetohigher-levelelectromagneticwavesforalongtime. |
10.Changethementalityofnotrelyingonelectricity | Thelifesurroundedbyelectrochemicalproductshasgreatlyincreasedthechanceofexposuretoelectromagneticwaves. |
Infact,notanyelectromagneticradiationhasanimpactonthehumanbody.Aslongastheintensityisnotlarge,itwillnotharmthehumanbodymuch.Asfortheanti-electromagneticradiationproductsonthemarket,mostofthemhavenoeffect.Don'tbefooled.Remember,themethodofshieldingelectromagneticwavescanbegroundedmetalmeshormetalplate,orthickconcreteormudcanbeusedtoabsorbit.Ifyoucannotshieldthestrongelectromagneticwaves,theonlywaytokeepyouunaffectedistostayawayfromtheradiationsource,becausetheintensityofelectromagneticwavesisinverselyproportionaltothesquareofthedistance,thatis,ifthedistanceistwicetheoriginal,theintensityisreducedtoaquarter.
Electromagneticpollution
Definition
Electromagneticwavepollution,alsoknownaselectromagneticpollutionorradiofrequencyradiationpollution.Itischaracterizedbythefieldforceoftheelectromagneticfieldandiscloselyrelatedtotheproperties,power,densityandfrequencyofelectromagneticwaves.Duetothewidespreadapplicationofelectronictechnology,therapiddevelopmentandpopularizationofradiobroadcasting,mobilephones,television,andmicrowavetechnology,thepowerofradiofrequencyequipmenthasdoubled,andtheelectromagneticradiationonthegroundhasincreasedsignificantly.Hasreachedalevelthatcandirectlythreatenhumanhealth.Electromagneticpollutionisaninvisiblepollutionthathasbecomeapublichazardthatpeopleareveryconcernedabout.Theimpactonhumansocietyhasattractedtheattentionofallcountriesintheworldandhasbeenlistedasoneoftheenvironmentalprotectionprojects.
Naturalpollution
Naturalelectromagneticwavepollutioniscausedbycertainnaturalphenomena.Themostcommonisthunderandlightning.Inadditiontodirectharmtoelectricalequipment,aircraft,buildings,etc.,thunderandlightningcanalsocausesevereelectromagneticinterferenceinawiderangeofextremelywidefrequencyrangesfromseveralthousandHztoseveralhundredMHz.Volcaniceruptions,earthquakes,andmagneticexplosionscausedbysunspotactivitycanallcauseelectromagneticinterference.Naturalelectromagneticwavepollutionhasextremelyseriousinterferencetoshortwavecommunications.
Man-madepollution
Man-madeelectromagneticwavepollutionincludes:
1.Pulsedischarge.Forexample,thesparkdischargegeneratedwhenthehigh-currentcircuitiscutoff,thetransientcurrentisverylarge,anditwillproducestrongelectromagnetic.Itisessentiallythesameaslightning,buttheareaofinfluenceissmaller.
2.Powerfrequencyalternatingelectromagneticfield.Forexample,theelectromagneticfieldnearhigh-powermotors,transformers,andtransmissionlinesdoesnotradiateoutwardintheformofelectromagneticwaves,butitwillcauseseriouselectromagneticinterferenceinthenear-fieldarea.
3.Radiofrequencyelectromagneticradiation.Forexample,theradiationofvariousradiofrequencyequipmentsuchasradiobroadcasting,television,microwavecommunication,etc.,hasawidefrequencyrangeandalargeimpactarea,whichcanharmthestaffinthenearfieldarea.Radiofrequencyelectromagneticradiationhasbecomethemainfactorthatelectromagneticwavespollutetheenvironment.
Waysoftransmission
1Radioandtelevisiontransmissionequipment,mainlyradiobroadcastingcommunications,isthetransmissionstationandrelaystationofvariousradioandtelevisiondepartments.
2Communicationsradarandnavigationtransmitterequipmentcommunications,includingshort-wavetransmitterstations,microwavecommunicationstations,groundsatellitecommunicationstations,andmobilecommunicationstations.
3Industrial,scientificresearch,andmedicalhigh-frequencyequipment.Thistypeofequipmentconvertselectricalenergyintoheatorotherenergyforuse,butitisaccompaniedbyelectromagneticradiationgeneratedandleakedout,causingenvironmentalpollutionintheworkplace.
Industrialelectromagneticradiationequipment:mainlyhigh-frequencyinductionheatingequipment,suchashigh-frequencyquenching,high-frequencyweldingandhigh-frequencyfurnace,high-frequencymeltingequipment,etc.,andhigh-frequencydielectricheatingequipment,suchasplasticheatsealingMachine,high-frequencydryingprocessor,high-frequencymediumheatingunit,etc.
Medicalelectromagneticradiationequipment:mainlyshortwaveandultrashortwavephysiotherapyequipment,suchashighfrequencyphysiotherapymachine,ultrashortwavephysiotherapymachine,ultravioletphysiotherapymachine,etc.
Scientificresearchelectromagneticradiationequipment:mainlyelectronacceleratorsandvariousradiationdevices,electromagneticstoves,etc.
4Electromagneticradiationinterferenceoftransportationsystems,including:electrifiedrailways,lightrailsandelectrifiedrailways,tramswithrails,tramswithoutrails,etc.
5Electromagneticradiationofpowersystems,high-voltagetransmissionlinesincludeoverheadtransmissionlinesandundergroundcables,andsubstationsincludepowerplantsandtransformerpowerstations.
6Electromagneticradiationofhouseholdappliances,includingmicrowaveheatingandemissionequipment,includingcomputers,monitors,televisions,microwaveovens,wirelessphones,etc.
Electromagneticwavepollutioninfamilylife,whichiscloselyrelatedtopeople’sdailylife,referstovariouselectroniclifeproducts,includingairconditioners,computers,televisions,refrigerators,microwaveovens,karaokemachines,VCDmachines,Displays,electricblankets,mobilephones,etc.,producevariouselectromagneticwavesofdifferentwavelengthsandfrequenciesduringnormaloperationthatinterferewith,affectandharmpeople.
Mainhazards
Becauseelectromagneticwavesarecolorless,tasteless,invisible,andwithouttraces,andpollutionisneithersensiblenorubiquitous,itiscalled"e-waste"byscientistsOr"electronicradiationpollution",theharmitbringstopeoplecannotbeunderestimated.Mainlymanifestedinthefollowingfouraspects:
1.Affectthenormaloperationofelectronicequipment
Moderntechnologyisincreasinglyinclinedtouselarge-scaleandverylarge-scaleintegratedcircuits,andthedensityofcircuitcomponentsisextremelyhigh.Inaddition,thecurrentusedisamicrocurrent,sothatthesignalpowerisalmostthesameasthenoisepower,andparasiticradiationmaycausemalfunctionsorobstaclesinelectronicsystemsorelectronicequipment.Ontheotherhand,withtherapiddevelopmentofmodernwirelesscommunicationindustry,varioustransmissiontowersmaketheairwavescrowded,whichseriouslyaffectsnormalbusinessinallaspects.BeginninginSeptember1996,therehavebeenfrequentincidentsinwhichtheaeronauticalcommunicationfrequencyofBeijingCapitalAirportabove1.30MHzwasinterferedbytheradiopagingstation.At8:15amonFebruary20,1996,theair-to-airchannelwasseverelydisrupted,and10aircrafthadtohoverintheairtowait.Asaresult,theaircraftleavingtheporthadtoextendtheflighttimeof5minutesto15minutes.Thesameincidenthappenedfrequentlyinotherpartsofthecountry.Inplaceswherepeopleareaccustomedtothinkthattheskyishighandbirdsfly,theinterferenceofelectromagneticwaveshasbroughtgreatharmtopeople.
2.Scientificresearchandfactsshowthatelectromagneticwavesarealsoextremelyharmfultothehumanbody.Theharmofelectromagneticradiationtothehumanbodyiscausedbytheenergyofelectromagneticwaves.Accordingtorelevantexperts,thetransmissionfrequencyofmobilephonesusedinmycountryisbetween800and1000MHz,andtheradiationdosecanreach600microwatts,whichismorethan10timeshigherthanthenationalstandard.Excessiveelectromagneticradiationcancausehumanneurasthenia,Lossofappetite,palpitations,chesttightness,dizzinessandother"electromagneticwavehypersensitivity"canevencausebraintumors.Manyexamplesofelectromagneticwavepollutiononthehumanbodyhavebeendiscovered,butthedegreeofitsimpactisrelatedtotheintensityofradiationreceivedandthelengthoftimeithasaccumulated.Ithasnotbeenreflectedonalargescale,soithasnotattractedpeople'sgeneralattention.Relevantstudieshaveshownthatthepathogeniceffectofelectromagneticwavesincreaseswiththeincreaseofthemagneticfieldvibrationfrequency,andthefrequencyexceeds100,000Hz,whichcanposeapotentialthreattothehumanbody.Workingandlivinginthisenvironmentforalongtime,thehumanbodyisinterferedbyelectromagneticwaves,whichchangestheoriginalelectricfieldofthemoleculesinthebodytissues,whichleadstothedisorderofthebody'secologicalbalance.Somepeoplewhohavebeenexposedtostrongorlong-termelectromagneticwaveradiationhavedevelopedpathologicalmanifestations,whicharemainlyreflectedinthenervoussystemandcardiovascularsystem.Suchasfatigue,memoryloss,insomnia,easyagitation,menstrualdisorders,chesttightness,heartpalpitations,leukocytesandthrombocytopeniaorlow,decreasedimmunefunction,etc.
3.Maycauseexplosivesorexplosivemixturestoexplode.Sometallmetalstructureswillproducesparkdischargeduetohighfrequencyinductionundercertainconditions.Thiskindofdischargenotonlygivespeopledifferentdegreesofelectricshock,butalsomaydetonatedangerousgoodsandcausecatastrophicconsequences.Thisisanissuethatneedstobepaidcloseattentiontoforexplosivesandpropellantmanufacturers.
4.Electromagneticradiationwillaffecthumanhealth.Electromagneticradiationisoneofthemaincausesofcardiovasculardisease,diabetes,andcancermutations.Electromagneticradiationcancausedirectdamagetothehumanreproductivesystem,nervoussystemandimmunesystem.Electromagneticradiationisoneofthepredisposingfactorsthatcausemiscarriage,infertility,andteratogenesisinpregnantwomen.Excessiveelectromagneticradiationdirectlyaffectsthedevelopmentofchildren'sbodytissuesandbones,leadingtodecreasedvisionandhematopoieticfunctionoftheliver.Inseverecases,itcanleadtoretinaldetachment.Electromagneticradiationcanreducemalesexualfunctionandfemaleendocrinedisorders.
Pollutionpath
Therearetwowaysofelectromagneticwaveinterferencepropagation:
Oneisconductedinterference,whichistheinterferencecausedbythecurrentpropagatingalongthepowerline;
Theotherisradiatedinterference,whichiscausedbytheemissionofelectromagneticwavesourcestothesurroundingspace.
Inordertopreventandsuppresselectromagneticinterference,technicalmethodssuchasreasonablecircuitdesign,filtering,andshieldingaremainlyused.Reasonabledesignofthecircuitistoarrangethecomponentsandlayoutthecircuitreasonablyinasmallspace,whichcanweakentheparasiticelectromagneticcouplingandsuppresstheelectromagneticinterference.Thefilterisacircuitcomposedofresistance,inductanceandcapacitance.Thisnetworkcanallowsignalsofcertainfrequenciestopass,whilepreventingsignalsofotherfrequenciesfrompassing.Thecorrectdesignandinstallationofthefiltercanminimizeelectromagneticinterference.Shieldingtechnologyhasbeenwidelyusedasabasicmeanstosuppresselectromagneticwaveradiation.Thepurposeofshieldingistolimittheradiatedenergytoaspecificarea,ortopreventtheradiatedenergyfromenteringanotherspecificarea.Shieldingmaterialsarethekeytoshieldingefficiency.Recentlydevelopedabsorbingmaterialshavecomeout,whichwillcontributetothecreationofcleanspaceformankind.Inadditiontotheabove-mentionedtechnicalmethodstosuppresselectromagneticradiationpollution,othermethodscanalsobeusedtoreduceitshazards,suchasprohibitingtheestablishmentofhigh-powerwirelesspagingstationsaroundtheairport,andadoptinggoodshieldingandprotectivemeasuresforworkerswhofrequentlycomeintocontactwithradiofrequencyequipment.
Inshort,withthedevelopmentofscienceandproduction,theharmofelectromagneticradiationpollutionisdeteriorating,anditisofgreatpracticalsignificancetostudytheharmandprotectionofelectromagneticwavepollution.
RelatedCases
Morethan20yearsago,afterhouseholdmicrowaveovenswerepopularizedintheUnitedStates,somepatientswithpacemakersoftenfeltunwell.SomepacemakersevenFailuretostopsuddenly.Later,scientists’researchmadethetruthknowntotheworld,andthereasonwas“electromagneticwavepollution”.
Inthepastfewyears,thefamousRussianchessmasterNikolaiKedkovplayedagamewithacomputer.Afterwinning3gamesinarow,hewassuddenlyknockeddownbythepowerfulcurrentreleasedbythecomputer.Theinvestigationconfirmedthatthiswasnotacomputerhardwareleakage,norwasitsoftwaredesignedtokillaperson,andthecauseofdeathwasinvisibleelectromagneticwaves.
Ithasbeenreportedthatworkerswhooperateinfrontofthecomputerformorethan6hoursadayarepronetoadiseasecalled"VOT".Thisdiseasereferstothegeneraltermthatcausescertainpartsofthebodytohavelesionscausedbywatchingthevideoterminalforalongtime.Itsmainsymptomsare:visualdysfunction;neck,shoulder,andwristdysfunction;autonomicdysfunction,etc.;inaddition,itcancausewomen'ssymptomssuchasirregularmenstruation,miscarriage,andotherskindiseases.Thereasonisalsocausedbyelectromagneticwaveradiation.
Mobilephonesandwalkie-talkiesarealsoasourceofhigh-frequencyelectromagneticwavepollution.Theyemitelectromagneticwaveseverytimetheymakeacall.Scientistsbelievethattheelectromagneticradiationintensityofmobilephonesgenerallyexceeds4-6timestheprescribedstandards,andsometypesevenexceednearlyahundredtimes.mycountry’sElectromagneticRadiationTestingCenterandXiamenChangqingyuanRadiationProtectionResearchInstitutehaveconfirmedaftertwoyearsoffollow-uptestingthatthemobilephonescurrentlyusedinmycountrywillcauseradiationhazardstothehumanbody.
Pollutionprevention
Therearemanyeasy-to-operatemeasurestoreducetheharmofelectromagneticwavepollution.
Therearetwogeneralprinciples:
First,becauseofworkneeds,youmustnotbefarawayfromtheelectromagneticwaveemissionsource,youmusttakeshieldingandprotectionmeasures;
Second,Trytoincreasethedistancebetweenthehumanbodyandtheemissionsource.
Becausetheimpactofelectromagneticwavesonthehumanbodyiscloselyrelatedtothesizeoftheemissionpowerandthedistancefromtheemissionsource,itsdegreeofharmisproportionaltotheemissionpowerandinverselyproportionaltothesquareofthedistance.Takeamobilephoneasanexample.Althoughitstransmittingpowerisonlyafewwatts,becauseitstransmittingantennaisveryclosetotheheadofaperson,theactualradiationintensityitreceivesisequivalenttoahundredsofkilowattsbroadcastatadistanceoftensofmeters.Theintensityofradiationreceivedbytheradiotransmittingantenna.Fortunately,peopleuseitforashorttimeandwillnotshowobvioussymptomsofharmforawhile;butafterlonguse,thesymptomscausedbyradiationwillgraduallybeexposed.Excessiveradiationwillcauseabnormalcellactivityanddivision,andcausecancer.Possible.
Inviewofthis,weshouldconsciouslytakemeasuresinourdailylivestoreducetheharmofelectromagneticwavepollution.Forexample,thosewhoworkinplaceswithhighelectromagneticwaveintensitysuchascomputerroomsshouldpayspecialattentiontorestduringwork,andtheycanperformactivitiesoutdoorsawayfromelectromagneticfields.Whenusingmobilephones,keeptheantennaawayfromthehumanbody,especiallythehead,asmuchaspossible.Andtrytoreducethetimeofeachcall;householdappliancesshouldnotbeplacedtogether,thedistancetowatchTVshouldbekeptat4to5meters,andattentionshouldbepaidtoopenwindowsforventilation;microwaveovensandrefrigeratorsshouldnotbeusedclosetoeachother;teenagersshouldnotplayvideogamesasmuchaspossible;electricheatingAftertheblanketiswarmedup,thepowershouldbecutoffwhenyoufallasleep.Childrenandpregnantwomenshouldnotuseelectricblankets;usually,eatmorefreshvegetablesandfruitstoenhancethebody'sabilitytoresistelectromagneticwavepollution.
One,keepyourdistance.ThedistancetotheTVshouldbethesizeofthescreenmultipliedby6,andthedistancetothemicrowaveovenshouldbe2.5to3meters.Thedistancefromthehigh-voltagepowerlineof5thousandvolts/meterisgenerallyregardedasasafearea.
Second,reducecontact.Peoplewhousecomputersfrequentlyshouldtakea15-minutebreakeveryhourofwork,andworknomorethan32hoursaweek.
Three,improvetheenvironment.Payattentiontoaircirculation,temperatureandhumidityshouldbemoderate,anditisbestnottoputhouseholdappliancesinthebedroom.
Four,personalprotection.Pregnantwomen,children,peoplewhoarefrailandsick,thosewhoareallergictoelectromagneticwaveradiation,andthosewhohavebeeninanenvironmentwhereelectromagneticwavepollutionexceedsthestandardforalongtime,shouldchoosetouseprotectiveequipmentthatsuitsthem.
Fifth,uselessmobilephones.Tominimizetheuseofmobilephones,walkie-talkies,andcordlessphones,youshouldmakealongstoryshortwhenyoumustusethem;don'thangyourmobilephonefrequentlyonyourbody.
Six.Uselesselectricblankets.Theelectromagneticwavepollutionofelectricblanketsisserious.Long-termuseofelectricityisharmfultothehumanbody.Whenitisnecessarytouseitincoldweather,itisrecommendedtocutoffthepowerimmediatelyafterheatingthebedtoreduceelectromagneticwavepollution.
Seven.Useshieldingtoreduceelectromagneticwavepollution.Forfacilitiesthatproduceelectromagneticpollution,shieldsthatshield,reflectorabsorbelectromagneticwaves,suchascopper,aluminum,steelplates,andpolymerfilms,canbeused.
8.Accordingtothecharacteristicsofelectromagneticwaveattenuationwithdistance,inordertoreducetheharmofelectromagneticwavestoresidents,workplacesandfacilitiesthatemithighelectromagneticpowerandmaygeneratestrongelectromagneticwaves,suchasTVstations,radiostations,andradarsCommunicationstations,microwavetransmissionstations,etc.,shouldbelocatedasfarawayaspossiblefromresidentialareasinoutlyingcountiesorhigh-lyingareas.Facilitiessuchassubstationsthatmustbeinstalledincities,adjacentresidentialareas,andplaceswhereresidentsoftenlive,shouldmaintainacertainsafetyprotectiondistancefromresidentialareastoensurethattheirboundariesmeettherequirementsofenvironmentalelectromagneticwavehealthstandards.Atthesametime,theelectromagneticwaveradiationsourceneedstobeelectromagneticallyshieldedfromcopper,aluminum,steelandothermetalwiresorpolymerfilmsthatcanshield,reflectorabsorbelectromagneticwaves,soastolimittheelectromagneticradiationenergywithinthespecifiedspace.
9.High-voltage,especiallyultra-high-voltagetransmissionlines,shouldbefarawayfromdenselypopulatedareassuchasresidentialbuildings,schools,andsportsfields.Whenusingacomputer,alow-radiationmonitorshouldbeused,andthedistancebetweenthehumanbodyandthefrontofthedisplayshouldbenolessthan75cm,andthesideandbackshouldbenolessthan90cm.Itisbesttoinstallshieldingdevices.
10.Thedensityofmobilecommunicationbasestationsshouldbestrictlycontrolledtoensurethattheantennasofvariousmobilecommunicationtransmittingbasestationsinstalledintheurbanareaarehigherthansurroundingbuildings,andwithinacertainrangearoundkindergartens,schoolbuildings,hospitalsandotherbuildingsDonotbuildatransmittingantenna.
11.Inordertoreduceelectromagneticpollutionanditsharmfuleffectsinthefamilyroom,theroomshouldbeventilatedfrequentlytokeeptheindoorairunblocked.Usehouseholdappliancesscientifically:Forexample,whenwatchingTVorhometheater,keepalongdistanceandavoidturningonallkindsofelectricalappliancesatthesametime;usingcomputersorelectronicgameconsolesshouldnotlasttoolong,etc.
12.Whenusingmobilephones,trytoreducethetimeoftalking;thetopofthemobilephoneantennashouldbeasfaraspossiblefromthehead,andtheantennashouldbestretchedasfaraspossible;installisolationlayersonthemobilephone.
13.Inaddition,youcantakeacertainamountofvitaminCeverydayoreatmorefreshvegetablesrichinvitaminC,suchaspeppers,bellpeppers,toon,cauliflower,spinach,etc.;eatmorefreshfruitssuchascitrus,Dates,etc.AlsopayattentiontoeatingmorefoodsrichinvitaminA,Candproteininthediet,suchastomatoes,leanmeat,animalliver,beansprouts,etc.;oftendrinkgreentea.Thesedietarymeasurescanactivelypreventandreducetheharmcausedbyelectromagneticradiationtothehumanbodytoacertainextent.
14.Electromagneticwaveradiationisanewtypeofenvironmentalpollutionthathasonlybeenrecognizedbypeopleinthepast30to40years.Peoplearestillinthestageofunderstandingandresearchingelectromagneticradiation.Becauseitisinvisible,intangible,anddifficulttodetect,itiseasytocausepeople'sdoubts.Inaddition,somereportsonelectromagneticradiationarenotobjectiveandscientific,leadingtounnecessarymisunderstandingsandpanic.Generallyspeaking,todeterminewhetherelectromagneticradiationcausespollutiontothelivingenvironment,itshouldbecomprehensivelyconsideredfromtheaspectsofelectromagneticwaveradiationintensity,mainradiationdirection,distancefromtheradiationsource,andduration.Therefore,whilestrengtheningelectromagneticprotection,weshouldalsoadoptascientificattitudetowardselectromagneticwavepollution,objectivelyanalyzeandtreatitseriously,andwemustnotblindlyexaggerateirresponsiblyandcauseconfusioninpeople'sunderstanding.Ofcourse,withthedevelopmentofscienceandtechnology,people'sunderstandingofelectromagneticwavepollutionanditsharmwillgraduallydeepen,andmanymysterieswilleventuallyberevealed.
Relatedregulations
Electromagneticenvironmentstandardsandrelatedregulations.Inordertocontrolthepollutionofelectromagneticwavestotheenvironmentinmodernlifeandprotectpeople’shealth,theMinistryofHealthofmycountrypromulgatedthe"EnvironmentalElectromagneticWaveHygieneStandards"(GB9175-88)onDecember22,1989,stipulatingthatthelimitvalueofenvironmentalelectromagneticwaveintensityinresidentialareas:long,ThemediumandshortwaveshouldbelessthanlOV/m,theultrashortwaveshouldbelessthan5V/m,andthemicrowaveshouldbelessthan10μW/cm2.Therelevantdepartmentsofourcountryhavealsoformulatedthe"RadiationHealthProtectionDistanceStandardsforTVTowers",andtheNationalEnvironmentalProtectionAgencyhasalsoissuedthe"ElectromagneticRadiationEnvironmentalProtectionManagementMeasures."
Inresponsetothedevelopmentofmobilecommunications,onFebruary17,2000,theBeijingMunicipalEnvironmentalProtectionBureaupromulgatedthecountry’sfirst"RegulationsontheEnvironmentalProtectionManagementofMobileCommunicationsConstructionProjectsinBeijing"(fortrialimplementation)forthestandardizedmanagementofelectromagneticpollution.),inordertostandardizetheconstructionandoperationofmobilecommunicationstations(stations)topreventthemfromcausingelectromagneticpollutiontotheenvironment.Theregulationsclarifythatmobilecommunicationstations(stations)capableofgeneratingelectromagneticradiationmustgothroughenvironmentalprotectionapprovalproceduresbeforeconstruction,andmustgothroughenvironmentalprotectionacceptanceapproval.Aftermonitoringbytheenvironmentalprotectiondepartment,thelocalpowerdensitymeetsthenational"ElectromagneticRadiationProtectionRegulations."Onlywhenthefrequencyintherangeof20MHz～3000MHzandthepowerdensityoftheradiationexportlimitiswithinthestandardof40μW/cm2canitbeofficiallyputintouse,andthosegreaterthanthisstandardmustbedisabledOrrectify;beforeconstructingcellularmobilecommunicationbasestations,itisnecessarytopredicttheuserdensitydistribution,adoptthebestfrequencyreusemethod,andminimizethenumberofbasestations;buildmobilecommunicationstations(stations)onresidentialbuildings,priorbuildingpropertyrightsunitsorpropertymanagementunitsTheopinionsoftheresidentsmustbeobtained;theminimumallowableheightofwirelesspagingcommunicationandtrunkingcommunicationantennasshallnotbelessthan40m,andtheoutdoorantennaofcellularmobilecommunicationbasestationsshallgenerallynotbelessthan25m,andthetransmittingantennashallbewithin50mofthemainradiationdirection,butnotthemainradiationdirection.Generally,hospitals,kindergartens,schools,residentialbuildingsandotherbuildingshigherthantheantennaarenotallowedtobebuiltwithin30m;theconstructionunitshouldsetupelectromagneticradiationwarningsignsattheinstallationlocationsoftheabove-mentionedantennas.