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The Electromagnetic Spectrum

Radio (AM, FM) Televis ion The Electromagnetic Spectrum GSM Badar Bluetocth Microwave Coped Cable (TV) Mser (Miaowave laser) Wireles LAN Moble Phones Heat Rate Mon tors Avdanche Beacons Sateltes Ranbow Microwaves 1.5 GHz - 0.3 THz | 20 cm 1000 pm Visible Color Vsion Color Theory Spechoscopy Can one touch light? X-Ray 375 THz - 789 THz I 780 nm - 380 nm 24 PHz- 12EHZ | 13 nm - 24 pm Submarine Communication Microwaves are absorbed by molecules that have a dipole moment in liquids. In a microwave oven, this effect is used to heat food. Low-intensity microwave radiation is used in Wi-Fi. The visible spectrum (or optical spectrum) is the portion of the electromag- netic spectrum that is visible to the human eye. Électromagnetic radiation in this range of wavekngths is caled visible light or simply light. If a little glæss bead is put on top of a powerful laser, the bead remains suspended in mid-air. The heaviest object that has been levitated with a laser had a mass of 20 g, the las er used was enormous, and the method also made use of a few additional effects, such as shock waves, to keep the object in the air This means that light has momentum. Therefore many languages it is called Röntgen radiation after the investigaitor of the radiation, Wilhelm Röntgen. EM raci ation exhibits both wave properties and particle properties at the same time. However, these characteristics are mutually exclusive and appear separately in different cicumstances: the wave characteris tics appear uhen EM radi ation is me asured over relatively large times cales and over large distances, and the particle characteristics are evident uhen measuring small distanc es and times cales. Both characteristics have been confirme d in a large number of experiments. We all know the waves the sea makes or the ones the wind c re ates on a flag We can touch them, interact and interfe re with them. Even soundtravels inwaves which we c an hear with the help of our e ar drums. These waves need a medium in which they create amolekular res onation and thereby propagate through space. Light is diffe re nt in this respe ct. Itis still understood as a wave but it does not needa medium to move through space. Thes e types of waves are called Electromagnetic Radioation (EM radiation) and belong to the electromagnetic spectrum of which light is only a very small part. Electromagnetic radi ation is generally described as a self-propagating wave in space with electric and magnetic components. These compon ents os cillate at right angles to each other and to the direction of propagation, and are in phase with each other. Electromagnetic radiati on is classified into types according to the frequency of the wave: these types include, in orde r of increasing frequency, radio waves, microwaves, infrared radiation, visible light, ultravialet radiation, X-rays and gamma rays. In some technical contexts the entire range is referre d to as just lighť. The super high frequency (SHF) and extremely high frequency (EHF) of Microwaves come next up the frequency sc ale. Microwaves are waves There are no exact bounds to the visible spectrum; a typical human eye will When medical X-rays are being produced, a thin metalli c sheet is placed The eyes of many species perceive wavelengths different from the spectrum visible to the human eye. For example, many ins ects, such as bees, can see light in the ultraviolet, which is useful for finding nectar in flowe is. For this res pond to wavelengths from 700 to 400 nm, although s cme people may be able to perceive wavelengths from 780 to 380 nm. A light-adapted eye typically has its maximum sensitivity at around 555 nm, in the green re gion of the optical spectrum (s ee: luminosity function). The spectrum does not, however, contain all the colors that the human eyes and brain can dis tinguish. Brown and pink are absent, for example. See Colorto understand wtry. between the emitter and the target, effectively filtering out the lower energy which are typic ally short enough to employ tubular metal wave gui des of reas onable diameter The average microwave oven in active condition is, in close range, powerful enough to caus e interfe rence with poorly shiel de d electromagnetic fields such as those found in mobile medical de vic es and che ap consumer electronics. (s oft) X-rays. The resultant X-ray is said to be hard Soft X-rays overlap the reason, plant species whos e life cycles are linked to insect pollin ation may owe their reproductive success to their appe arance in ultraviolet light. Thus, the true color of flowers may be in the ultravialet spectrum. images can be touchedl In fact, the ease with uhich objects can be pus hed even has a special name. For stars, it is called the albedg and for general objects it is called the reflectivity. Like each type of electromagnetic field, and like every kind of wave, light carries energy. range of extreme ultraviolet. The frequency of hard X-rays is higher than that of soft X-tays, and the wavelength is shorter Hard X-tays overlap the range of "long"-wavelength (lower energy) gamma rays, howe ver the distinction between the two terms depends on the source of the radiation, not its wavelength; X-ray photons are generated by energetic electron processes, gamma rays by transitions within atomic nuclei. The basic production of X-rays is by accelerating electrons in order to collide with ametal target (usually tungsten, but sometimes molybdenum). Here the electrons suddenly decelerate upon colli ding with the metal target and if enough ene rgy is contained within the ele ctron it is able to knock out an electron from the innershell of the metal atom and as a result electrons from higher energy levels then fill up the vacancy and X-ray photons are emitted. Gamma Rays Hedng Thermography Night Vs ion Spechoscopy >12 EHz I >24 pm Sta lization Medicine Infrared Optical Window Gamma rays (often denoted by the Greek letter gamma) are an energetic form of electro- magnetic radiction produced by radioactive decay or other nuclear or subatomic proc- 0.3 THz - 375 GHz | 1000 pm -780 nm Infraed Dda Associdtion (IDA) esses such as electron-positron annihikrtion. The name Infrared means "below red", from the Latin infra, "below", and red being the color of visible light of longest wavelength. In astronomy, the optical window is that the eye can use, oughly 400-700 nm and portion of the electromagnetic spectrum that passes through the atmosphere all the way to the ground Most EM ene rgy never makes it through the atmosphere, so this is like a window that lets in just a little of what the "radio window" that lets through some is out there. It is called "optical because the (not all) radio waves. The racio window wavelengths we can see are all in this range. continues up through the visual infrared to around 1100 nm, uhich is themal infrared Gamma rays form the highest-energy end of the ele ctrom agnetic spectrum. They are used for a range of applications in both medicine and industry. It is important to note that there is no physic al difference between gamma rays and X-rays of the s ame energy -they are two names for the same electromagnetic radiation, just as sunlight and moonlight are two names for visible light. Rather, gamma rays are distinguis hed from X-rays by their ongin. Gamma ray is aterm for high-energy electromagnetic radi ation produced by nucle ar transitions, while X-1ay is a te m for high-energy electromagnetic radiation produced by energy trans iti ons due to accelerating electrons. Becaus e it is possible fors ome electron transitions to be of higher energy than s ome nuclear transitions, there is an ove zlap between wh at we call low energy gamma rays and high energy X-rays. Radio (AM, FM) Television The boundary between visible and infram d light is not precisely defined The human eye is markedly less sensitive to light above 700 nm wavelength, so longer frequencies make insignificant contributions to scenes illumin ated by common light s ources. But particularly intense light (e.g, fram las ers, or from bright daylight with the visible light removed by coloured gels) can be detected up to approximately 780 nm, and will be perceived as red light. The onset of in frared is define d (according to diffe rent standards) at various values typically between 700 nm and 780 nm. Sdelte Navigation Mcbile Phones Two-Way Radios Black lights Flucres cent lamps Spechophotom ery Pest control Phololthography Sterlizalion Cuư ng of adhes wes There is another absorption window called Heat Rae Monitors Avalanche Beacors Sutmane Communication runs from about one centimeter to about Radio 10 Hz - 1.5 GHz | 30'000'000 km - 0.2 m Ultra-Violet 789 THz- 24 PHz | 380 nm - 13 nm The window runs from around ultravialet eleven meter vaves. (300 nm) at the short end up into the range Radio frequency refers to that portion of the electromagnetic spectrum in which electromagnetic waves can be generated by alterncrting current fed to an antennci. In humans, proonged exposure to solar UV radiation may result in ccute cind chronic heath effects on the skin, eye, cand immune system. Infrared radiation is popularly knowm as "heat" ors ometimes "heat radiation," since many people (even physics teachers) att ribute all radiant heating to in frared light, a wides pread misconception. Light and electromagnetic waves of any frequen cy will he at surfaces which absorb them. IR light from the sun only accounts for 50% of the he ating of the Earth, the rest beingcaused by visible light. Green (or even UV) lasers can charpapet, incandescently hot objects put out visible radiation, andice cubes emit mostly microwaves. However it is true that objects at room temperature will emit radi ation mostly conc entrated in the 8-12 micron band Unlike true heat, which exists Wavelength & Frequency As a defense against UV radi ation, the body tans when exposed to moderate (de pen ding an skin type) levels of radiation by releasing the brown pigment melanin. This helps to block UV penetration and prevent damage to the vulnerable skin tis sues deeper down. A positive effect of UV light is thatit induces the procuction of vitamin Din the skin. Radio waves generally are utiliz ed by antennas of appropriate size with wavelengths ranging from hun dreds of metres to about one millimetre. Wavekngth Radio waves, television waves, and microwaves are all types of electromagne tic waves. They only differ from each FM = Freguency Modulation AM = Amplitude Modulation They are used for transmission of data, viamodulation. Television, mobile phones, wireless networking and amateur radio all use radio waves. Above 300 GHz, the abs orption of electromagnetic radiation by Earth's atmosphere is so great that the atmosphere is effectively opaque to higher frequencies of electromagnetic radiation, until the atmos phere becomes transparent again in /Crest Crest other in wavelength. Wave- length is the distance between one wave crest to the next. Extreme UVis characterized by a transition in the plysics of interaction with matter: wavelengths longer than about 30 nm interact mainly with the chemical valence electrons of matter while wavelengths shorter than that interact mainly with inner shell ele ctrons and nuclei. the so-called infrared and optical window frequency ranges. Trough only in matter, in frared radi ation can propagate through a vacuum. ... ....

The Electromagnetic Spectrum

shared by smombartz on Nov 10
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A visualization of the electromagnetic spectrum, its different wavelengths and their uses.

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