Electromagnetic WAVES IN THE Spectrum

Submitted by:Elka Erin A. Santiago / 10-AguinaldoSubmitted to:Maam Jenny Rose DagtingElectromagnetic Spectrum

Theelectromagnetic spectrumis therangeof all possible frequencies of electromagnetic radiation.The "electromagnetic spectrum"of an objecthas a different meaning, and is instead the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.The electromagnetic spectrum extends from below the low frequencies used for modernradiocommunication togamma radiationat the short-wavelength(high-frequency) end, thereby covering wavelengths from thousands ofkilometersdown to a fractionof the size of anatom. The limit for long wavelengths is the size of theuniverse itself, while it is thought that the short wavelength limit is in the vicinity of thePlanck length.Until the middle of last century it was believed by most physicists that this spectrum wasinfiniteandcontinuous.Most parts of the electromagnetic spectrum are used in science for spectroscopic and other probing interactions, as ways to study and characterize matter.In addition, radiation from various parts of the spectrum has found many other uses for communications and manufacturing.For most of history, visible light was the only known part of the electromagnetic spectrum. Theancient Greeksrecognized that light traveled in straight lines and studied some of its properties, includingreflectionandrefraction. The study of light continued, and during the 16th and 17th centuries conflicting theories regarded light as either a wave or a particle.REFERENCE: https://en.wikipedia.org/wiki/Electromagnetic_spectrum http://physics.tutorvista.com/waves/electromagnetic-waves.html https://en.wikipedia.org/wiki/Microwave https://en.wikipedia.org/wiki/Infrared https://en.wikipedia.org/wiki/Light https://en.wikipedia.org/wiki/Ultraviolet https://en.wikipedia.org/wiki/Ultraviolet#/media/File:UV-handlamp_hg.jpg https://en.wikipedia.org/wiki/X-ray https://www.google.com.ph/search?biw=1821&bih=889&tbm=isch&sa=1&btnG=Search&q=ultravioletelectromagnetic+wave https://en.wikipedia.org/wiki/Gamma_ray https://www.google.com.ph/search?biw=1821&bih=889&tbm=isch&sa=1&btnG=Search&q=ultravioletelectromagnetic+wave#tbm=isch&q=gamma+rays+electromagnetic+spectrum

Radio Waves

Radio wavesare a type ofelectromagnetic radiationwithwavelengthsin theelectromagnetic spectrum longer thaninfraredlight. Radio waves havefrequenciesfrom 300GHzto as low as 3kHz, and corresponding wavelengths ranging from 1 millimeter (0.039in) to 100 kilometers (62mi). Like all other electromagnetic waves, they travel at thespeed of light. Naturally occurring radio waves are made by lightning, or byastronomical objects. Artificially generated radio waves are used for fixed and mobileradio communication,broadcasting,radarand other navigation systems,communications satellites, computer networks and innumerable other applications. Radio waves are generated byradio transmittersand received byradio receivers. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves candiffractaround obstacles like mountains and follow the contour of the earth (ground waves), shorter waves can reflect off theionosphereand return to earth beyond the horizon (sky waves), while much shorter wavelengths bend or diffract very little and travel on aline of sight, so their propagation distances are limited to the visual horizon.To preventinterferencebetween different users, the artificial generation and use of radio waves is strictly regulated by law, coordinated by an international body called theInternational Telecommunications Union (ITU). Theradio spectrumis divided into a number ofradio bandson the basis of frequency, allocated to different uses. Micro Waves

Microwavesare a form ofelectromagnetic radiationwithwavelengthsranging from as long as one meter to as short as one millimeter; withfrequenciesbetween 300MHz (100cm) and 300GHz (0.1cm). This broad definition includes bothUH FandEHF(millimeter waves), and various sources use different boundaries. In all cases, microwave includes the entireSHF band (3 to 30GHz, or 10 to 1cm) at minimum, withRF engineeringoften restricting the range between 1 and 100GHz (300 and 3mm).Theprefixmicro-inmicrowaveis not meant to suggest a wavelength in the micrometer range. It indicates that microwaves are "small", compared to waves used in typicalradio broadcasting, in that they have shorter wavelengths. The boundaries betweenfar infrared,terahertz radiation, microwaves, andultra-high-frequencyradiowavesare fairly arbitrary and are used variously between different fields of study.Beginning at about 40GHz, the atmosphere becomes less transparent to microwaves, at lower frequencies toabsorption from water vapor and at higher frequencies from oxygen. A spectral band structure causes absorption peaks at specific frequencies (see graph at right). Above 100GHz, the absorption of electromagnetic radiation by Earth's atmosphere is so great that it is in effectopaque, until the atmosphere becomes transparent again in the so-calledinfraredandoptical window frequency ranges. Infrared Rays

Infrared(IR) is invisible radiant energy,electromagnetic radiationwith longerwavelengthsthan those ofvisible light, extending from the nominalrededge of thevisible spectrumat 700nanometers(frequency430THz) to 1mm (300GHz)](although people can see infrared up to at least 1050nm in experiments). Most of thethermal radiationemitted by objects near room temperature is infrared.Infrared radiation was discovered in 1800 by astronomer SirWilliam Herschel, who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect upon a thermometer. Slightly more than half of the total energy from the Sun was eventually found to arrive on Earth in the form of infrared. The balance between absorbed and emitted infrared radiation has a critical effect on Earth'sclimate.Infrared energy is emitted or absorbed bymoleculeswhen they change theirrotational-vibrationalmovements. Infrared energy excitesvibrationalmodes in amoleculethrough a change in thedipole moment, making it a useful frequency range for study of these energy states for molecules of the proper symmetry.Infrared spectroscopyexamines absorption and transmission ofphotonsin the infrared energy range. Visible Light

Lightiselectromagnetic radiationwithin a certain portion of theelectromagnetic spectrum. The word usually refers tovisible light, which isvisibleto thehuman eyeand is responsible for the sense ofsight.Visible light is usually defined as havingwavelengthsin the range of 400700nanometres(nm), or400109mto700109m, between theinfrared(with longer wavelengths) and theultraviolet(with shorter wavelengths).This wavelength means a frequency range of roughly 430750terahertz(THz). Often, infrared and ultraviolet are also calledlight.The main source of light on Earth is theSun. Sunlight provides the energy that greenplantsuse to create sugars mostly in the form of starches, which release energy into the living things that digest them. This process of photosynthesis provides virtually all the energy used by living things. Historically, another important source of light for humans has been fire, from ancient campfires to modern kerosene lamps. With the development ofelectric lightsandof power systems, electric lighting has all but replaced firelight. Some species of animals generate their own light, calledbioluminescence. For example, fireflies use light to locate mates, and vampire squids use it to hide themselves from prey.Primary properties of visible light areintensity, propagation direction,frequencyorwavelengthspectrum, andpolarisation, while itsspeedin a vacuum, 299,792,458 meters per second, is one of the fundamentalconstantsof nature. Visible light, as with all types of electromagnetic radiation (EMR), is experimentally found to always move at this speed in vacuum Ultraviolet Ultraviolet(UV) light is anelectromagnetic radiationwith awavelengthfrom 400nm to 100nm, shorter than that ofvisible lightbut longer thanX-rays. Though usually invisible, under some conditions children and young adults can see ultraviolet down to wavelengths of about 310nm,and people withaphakia(missing lens) can also see some UV wavelengths. Near-UV is visible to a number of insects andbirds.UV radiation is present insunlight, and is produced byelectric arcsand specialized lights such as mercury-vapor lamps,tanning lamps, andblack lights. Although lacking theenergytoionize atoms, long-wavelength ultraviolet radiation can causechemical reactions, and causes many substances to glow or fluoresce. Consequently, biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules.Suntan,frecklingandsunburnare familiar effects of over-exposure, along with higher risk ofskin cancer. Living things on dry land would be severely damaged by ultraviolet radiation from the sun if most of it were not filtered out by the Earth's atmosphere, particularly theozone layer. More-energetic, shorter-wavelength "extreme" UV below 121nm ionizes air so strongly that it is absorbed before it reaches the ground.Ultraviolet is also responsible for the formation of bone-strengtheningvitamin Din most land vertebrates, including humans. The UV spectrum thus has effects both beneficial and harmful to human health.

X-rays X-radiation(composed ofX-rays) is a form ofelectromagnetic radiation. Most X-rays have a wavelengthranging from 0.01 to 10nanometers, corresponding tofrequenciesin the range 30petahertzto 30exahertz(31016Hz to 31019Hz) and energies in the range 100eVto 100keV. X-ray wavelengths are shorter than those ofUVrays and typically longer than those of gamma rays. In many languages, X-radiation is referred to with terms meaningRntgen radiation, afterWilhelm Rntgen, who is usually credited as its discoverer, and who had named itX-radiationto signify an unknown type of radiation. Spelling ofX-ray(s)in the English language includes the variantsx-ray(s),xray(s)andX ray(s). X-rays with photon energies above 510 keV (below 0.20.1nm wavelength) are calledhard X-rays, while those with lower energy are calledsoft X-rays.]Due to their penetrating ability, hard X-rays are widely used to image the inside of bjects, e.g., inmedical radiographyand airport security. As a result, the termX-rayismetonymicallyused to refer to aradiographic image produced using this method, in addition to the method itself. Since the wavelengths of hard X-rays are similar to the size of atoms they are also useful for determining crystal structures byX-ray crystallography. By contrast, soft X-rays are easily absorbed in air and theattenuation lengthof 600 eV (~2nm) X-rays in water is less than 1 micrometer.

Gamma Rays

Gamma radiation, also known asgamma rays,and denoted by the Greek letter, refers toelectromagnetic radiation of an extremely high frequency and therefore consists of high-energyphotons. Gamma rays areionizing radiation, and are thus biologically hazardous. They are classically produced by the decay ofatomic nucleias they transition from a high energy state to a lower state known asgamma decay, but may also be produced by other processes.Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium. Villard's radiation was named "gamma rays" byErnest Rutherfordin 1903.Natural sources of gamma rays on Earth include gamma decay from naturally occurringradioisotopes, and secondary radiation from atmospheric interactions withcosmic rayparticles. Rare terrestrial natural sources produce gamma rays that are not of a nuclear origin, such aslightning strikesandterrestrial gamma-ray flashes. Additionally, gamma rays are produced by a number of astronomical processes in which very high-energy electrons are produced, that in turn cause secondary gamma rays viabremsstrahlung, inverseCompton scattering, andsynchrotron radiation. However, a large fraction of such astronomical gamma rays are screened by Earth's atmosphere and can only be detected by spacecraft.