ELECTROMAGNETIC SPECTRUMName: ________________

Class: _________________

Index: ________________

At the end of the topic you should be able tostate that all electromagnetic waves are transverse waves that travel with the same high speed in vacuo and state the magnitude of this speeddescribe the main components of the electromagnetic spectrumdiscuss the role of the following components in the stated applications:radiowaves in radio and television communicationmicrowaves in satellite television and microwave oveninfra-red waves in infra-red remote controllers and intruder alarmslight in optical fibres for medical uses and telecommunicationsultra-violet in sunbeds, and sterilisationX-rays in radiological and engineering applicationsGamma rays in medical treatment describe the effects of absorbing electromagnetic waves, e.g. heating, ionisation and damage to living cells and tissue

Electromagnetic Spectrum

Properties An electromagnetic wave is produced by the simultaneous vibration of electric and magnetic fields.All electromagnetic wavestransfer energy from one place to anotherare transverse wavescan travel through vacuum. They DO NOT require any medium to travel from one point to another.travel through a vacuum at the speed of 3 x 108 ms-1.obey wave properties like reflection and refraction.carry no electrical charge as they are neither positively nor negatively charged. obey the wave equation: v = f.

If electromagnetic waves travel in vacuum, then for the wave equationv = f v = c, where c is the symbol for the speed of light in vacuum c = f 3.0 x 108 = fTheir frequencies do not change when they travel from one medium to another. (e.g.. From water to glass). This is because their frequency depends only on the source of the wave. Only their speeds and wavelengths change from one medium to another.

Components of electromagnetic spectrumSpeed in a vacuumis constant c = 3 x 108 m s-1low frequency high frequencyshort wavelengthlong wavelengthSeveral km< 10-12 mElectromagnetic spectrumRonald McDonald Is Very Ugly eXcept Gary

Electromagnetic SpectrumGamma raysX-raysUltraviolet Visible lightInfraredMicrowaveRadio wave

For each component, you need to know Range of wavelength Its uses Any harmful effects (The higher the frequency, the larger the amount of energy) Source Detector Applications of electromagnetic spectrum

Radio wavehas wavelength of 10-1 to 105 m Can move around obstaclesis used in radio communication and television transmission over long distances (LW, MW, SW, VHF, UHF). Radio telescope.Television transmission is made possible with the use of VHF and UHF radio wavessource: TV and radio transmittersdetector: aerials of TV and radio receivers/antenna

Microwave has wavelength of 10-3 to 10-1 m (0.001 m to 0.1m)is used in satellite communication and transmission, radar systems and microwave cooking/microwave oventravels in straight line without losing much of its energysource: electronic devices (eg. cavity magnetron in microwaves)detector: microwave receiversspeed-monitoring radarsatellite station

Infrared radiationis the radiation beyond the red end of the visible spectrumhas wavelength of 10-7 to 10-3 mis used in remote control devices, intruder alarms, infra-red photography and radiant heatersis emitted by hot objectssource: warm bodiesdetector: special photographic films, blackened thermometers and thermocouplesan infra-red photograph

Visible light can be seen by human eyehas wavelength of 4 x 10-7 to 7 x 10-7 mis used in optical fibres, medical usage, telecommunications, chemical spectral analysis and photosynthesis, endoscopy. Lasers for medical, industrial and surveying use.source: hot bodies, lasers and sundetector: eyes, photographic film and photocellslaser surgery

Ultraviolet radiationhas wavelength of 10-8 to 10-7 m stimulates our bodies to produce vitamin DCan cause tanning, overexposure can lead to skin canceris used in sunbeds, fluorescent tubes, sterilisation, forgery detection and fluorescence in washing powderssource: sun, mercury vapour and lampsdetector: photographic film, fluorescent screens, dyes and photocellsoverexposure to UV radiation can cause skin cancer

X rayhas wavelength of 10-13 to 10-8 m is penetrating and can cause damage to tissues and organismsDoctors, nurses and people working in X-ray environment have to wear protective clothing to shield themselves from X rayis used in medical and dental diagnostic tools and engineering applications. Check for flaws/cracks in metals. Detect artwork forgery. Airport scanners. Crystal structure analysis.source: x-ray tubesdetector: photographic film and fluorescent screensx-ray photograph of hand

Gamma ray (HIGHEST ENERGY!!!!, HIGHEST FREQUENCY)has wavelength of 10-14 to 10-10 m is penetrating and can cause damage to living tissues and organismsis used in treatment of cancer (gamma knives sharp beam of gamma ray) and checking of welds, under controlled situations. Sterilising equipment.source: cosmic rays, radioactive substances and nuclear reactiondetector: Geiger-Mller counters (GM tube), bubble/cloud chambers and photographic film

Effects of EM Waves on Cells and TissueExposure to electromagnetic radiation primarily causes heating effects such as the pain of sunburn or skin cancer. However, over-exposure may result in harmful effects such as pain of sunburn or skin cancer.EM waves can be classified as either ionising radiation or non-ionising radiation: Ionising radiations are extremely high frequency EM waves which include X-rays and gamma rays. They have enough photon energy to produce ionisation (a process where one or more electrons are removed from a neutral atom by radiation). It is a harmful process leading to destruction or modification of living cells. Non-ionising radiations are the part of the EM spectrum which has photon energies too weak to produce ionisation. Examples are ultra-violet, visible light, infra-red radiation, microwave and radio wave.

Memory aid (song) for Electromagnetic Spectrumhttp://www.youtube.com/watch?v=bjOGNVH3D4Y

Electromagnetic wavesc = 3 x 108 m s-1Transverse wavesComponentsRadio waves

Microwaves

Infra-red waves .

Light

Ultra-violet .X-rays

Gamma raysApplicationsRadio and television communicationSatellite television and telephoneHome electrical appliances, remote controls and intruder alarmsOptical fibres in medical usage and telecommuncationSunbeds, fluorescent tubes and sterilisationMedical use and engineering applicationsMedical treatment

Reference:http://blogs.edf.org/climate411/2007/07/25/greenhouse_effect/http://www.ehow.com/how_2001650_advantages-dishnetwork-cable.htmlhttp://www.smh.com.au/news/technology/police-grapple-with-defective-detectors/2008/07/22/1216492432489.htmlhttp://www.teara.govt.nz/en/auckland-places/1/4http://www.snowyrangevision.com/laserSurgery.htmlhttp://www.faqs.org/photo-dict/phrase/710/x-ray.html