Electromagnetic Spectrum
Ultraviolet Discovery (Latin, ultra "beyond") (violet being the color of the highest frequencies of the visible light) beyond violet
-1801 -Johann Ritter (German Physicist) -conducted an experiment to investigate the existence of energy beyond the violet end of the visible spectrum. -Discovered by Johann Wilhelm Ritter in 1801 -He called them "Oxidizing Rays" to emphasize the chemical reactivity and to distinguish them from "Heat Rays"
Electromagnetic waves
-A moving charge creates magnetic field. -A changing magnetic field causes a changing electric field. -The successive production of electric and magnetic field results to the creation EM wave. -An EM wave propagates outward from the source.. -Do not need matter to transfer energy. -Transverse waves -Are made by vibrating electric charges and can travel through space by transferring energy between vibrating electric and magnetic fields. -The magnetic and electric fields create each other again and again. -An EM wave travels in all directions. The figure only shows a wave traveling in one direction. -The electric and magnetic fields vibrate at right angles to the direction the wave travels so it is a transverse wave.
HISTORY OF THE DISCOVERY OF INFRARED WAVES
-British astronomer William Herschel discovered infrared light in 1800, according to NASA. Herschel performed further experiments on what he called the "calorific rays" that existed beyond the red part of the spectrum and found that they were reflected, refracted, absorbed and transmitted just like visible light. What Sir William had discovered was a form of light (or radiation) beyond red light. These "calorific rays" were later renamed infrared rays or infrared radiation (the prefix infra means `below'). -Herschel's experiment was important not only because it led to the discovery of infrared, but also because it was the first time that someone showed that there were forms of light that we cannot see with our eyes. In an experiment to measure the difference in temperature between the colors in the visible spectrum, he placed thermometers in the path of light within each color of the visible spectrum. He observed an increase in temperature from blue to red, including an even warmer temperature measurement just beyond the red end of the visible spectrum.
GAMMA RAY BURST
-GAMMA RAY BURSTS ARE THE MOST ENERGETIC AND LUMINOUS ELECTROMAGNETIC EVENTS SINCE THE BIG BANG AND CAN RELEASE MORE ENERGY IN 10 SECONDS THAT OUR SUN WILL EMIT ITS ENTIRE 10-BILLION-YEAR EXPECTED LIFETIME -ARE EXTREMELY HIGH-ENERGY EVENTS THAT LASTS ONLY A FEW MILLISECONDS TO SEVERAL MINUTES. -FIRST OBSERVED IN THE 1960'S
USES of RADIO WAVES
-Global Positioning Systems (GPS) measure the time it takes a radio wave to travel from several satellites to the receiver, determining the distance to each satellite. Radio telescope A radio telescope is a form of radio receiver used in astronomy. In contrast to an "ordinary" telescope, which receives visible light, a radio telescope "sees" radio waves emitted by radio sources, typically by means of a large parabolic ("dish") antenna, or arrays of them. -A radio picks up radio waves through an antenna and converts it to sound waves. Each radio station in an area broadcasts at a different frequency. # on radio dial tells frequency. -Radio Navigation Systems are the basis for landing of the aircraft, regardless of whether are concerned en-route or terminal means. Cellular telephones Wireless LANs Keyless entry AM & FM radio Garage-door openers Satellite radio Police radar Radar detectors Doppler radar Satellite tracking & communications
MORE ABOUT IR
-Infrared rays are being used by medical professionals to detect hard-to-find veins when doing venipuncture and cannulation. -Humans, at normal body temperature, radiate most strongly in the infrared at a wavelength of about 10 microns. -In firefighting, infrared cameras are being used to locate people or animals in heavy spots and to detect hot spots in forest fires. -Thirty minutes in an infrared sauna burns hundreds of calories and makes you sweat off 500 grams in one session. -Weather forecasters use satellite pictures to see what's heading our way. Some of the images they use are taken using IR cameras, because they show cloud and rain patterns more clearly.
Hazards of UV Rays
-Large doses of UV rays can damage the retina in your eyes -Suppression of the Immune System -Can cause sunburn and even skin cancer Sunburn (erythema) - is redness of the skin, which is due to increased blood flow in the skin caused by dilatation of the superficial blood vessels in the dermis as a result of exposure to UV radiation Tanning - refers to delayed pigmentation of the skin, or melanin pigmentation Premature aging of the skin - encompasses a number of clinical signs that reflect structural changes in the dermis Eye problems - Corneal damage, cataracts, and macular degeneration are all possible chronic effects from UV exposure and can ultimately lead to blindness - Melanoma, a type of skin cancer, can also develop within the eye Suppression of the immune system resulting from exposure to UV radiation is believed to be an important contributor to the development of non-melanoma skin cancers Skin cancer - exposure to UV radiation is thought to be an important factor for cancers as it induces DNA damage
Microwave Trivias
-Microwaves are almost always present on the Earth's surface. -It is possible to transmit data using microwaves. -The longest waves are over 100 kilometers long; the shortest are less than a billionth of a millimeter long. -Microwave communication is used by NASA and other space agencies for deep space communication. -In 1959 U.S. Navy engineers discovered that microwaves could bounce off objects in the solar system. -Microwaves are defined as radio waves with a wavelength in the range of 3,000 to 30,000 MHz. -Some believe that by cooking food with microwaves, nutrients such as vitamins and minerals are decreased or even destroyed. -The microwave was designed to use a magnetron to create the microwaves that cook or heat food or liquid. -NASA uses microwave technology for communication in deep space.
Ernest Rutherford
-Named Villard's rays "gamma rays" by analogy with the beta and alpha rays -Differentiated alpha and beta rays in 1899.
HISTORY of RADIO WAVES
-Radio waves were first predicted by mathematical work done by Scottish mathematical physicist James Clerk Maxwell. Maxwell noticed wavelike properties of light and similarities in electrical and magnetic observations. -Heinrich Hertz demonstrated the reality of Maxwell's electromagnetic waves by experimentally generating radio waves in his laboratory, showing that they exhibited the same wave properties as light: standing waves, refraction, diffraction, and polarization. Radio waves, originally called "Hertzian waves", were first used for communication in the mid 1890s by Guglielmo Marconi, who developed the first practical radio transmitters and receivers. The modern term "radio wave" replaced the original name "Hertzian wave" around 1912. -Guglielmo Marconi was awarded the Nobel Prize in physics in 1909 to commemorate his development of wireless telegraphy after he was able to send a long-wave radio signal across the Atlantic Ocean.
The Electromagnetic Spectrum
-The range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies. Longest to Shortest Wavelength= RW,MW,IR,VL,UW,XR,GR Longest to Shortest Frequency= GR, XR, UV, VL, IR, MW, RW High Frequency EM- UV, XR, GR Low Frequency EM- IR, MW, RW
Ultraviolet Trivias
-UV light is generated predominantly by hot, young massive stars. -Humidity may increase the effects of UV light. -UV traps are used to eliminate various small flying insects. -Snow reflects up to about 80% of the UV light. -Elephants are wise enough to protect their skins. To avoid the UV radiation damage as well as the sunburn, they cover themselves with a layer of mud during hot sun. -You can still get UV radiation when it's snowing outside. UV light is most apparent between 10 am in the morning and 4 pm. -UV light travels faster than standard light rays. -Some secretions and urine from a few species of the rodents reflect the UV light strongly than other substances around them. -Police use UV lights in forensics. A special powder is poured in the area under investigation, and UV light used to detect prints made by fingers and shoes. These prints are used to get possible suspects in crime scenes.
Uses of UV Rays
-Uses for UV light include getting sun tan -Detecting forged bank notes in shops -Hardening some types of dental filling -The lamps are sometimes called "blacklights" because we can't see the UV coming from them -Used to kill microbes -Hospitals use UV lamps to sterilize surgical equipment and the air in operating theaters -Causes the body to produce Vitamin D Counterfeit -Sensitive documents include UV watermark that is only seen under UV-emitting light. Crime Investigation -used to locate body fluids just like semen and saliva. Sterilizing Water -used in sterilizing water for it kills living cells. Washing -used to make shirts look whiter than white in daylight. Health -produces vitamin D and gives tanning effect.
Extra Infos RW
-Wi-fi uses radio waves that are routed through a wireless internet router using radio waves in frequencies between 2.4 and 5.8 GHz. -When a radio wave is received in a radio the tuner is what makes it possible to pick up a specific radio station because it makes it possible to listen to particular radio waves and tune out others. -A radio wave can be very short or very long. Wavelengths can reach 62 miles. -RW will bounce off items if not absorbed.
UVA Rays
-age skin cells and can damage their DNA -these rays are linked to long-term skin damage such as wrinkles, but they are also thought to play a role in some skin cancers
What are Gamma Rays?
-are the most energetic among all the electromagnetic waves -Gamma ray emission commonly occurs within a fraction of a second after radioactive decay. -Gamma-ray photons generally have energies greater than 100 keV. -Gamma rays have the smallest wavelengths and the most energy of any wave in the electromagnetic spectrum. -They are produced by the hottest and most energetic objects in the universe, such as neutron stars and pulsars, supernova explosions, and regions around black holes. -Brighter colors in the Cygnus region indicate greater numbers of gamma rays detected by the Fermi gamma-ray space telescope. Credit: NASA/DOE/International LAT Team -are the most dangerous of all electromagnetic waves. They can penetrate through any gap, even a subatomic one.
UVC Rays
-have more energy than the other types of UV rays, but they don't get through our atmosphere and are not in sunlight
UVB Rays
-have slightly more energy than UVA rays -they can damage skin cells' DNA directly, and are the main rays that cause sunburns.
Extra Infos GR
-played a key role in the discovery of the Higgs boson -nuclear reactions are a major source of gamma rays -gamma rays (indirectly) give life to Earth -scanning human tissue due to its penetration power -to study gamma rays, astronomer build telescopes in space -doctors conduct brain surgery using "gamma ray knives"
UV Index
1-2 Low -Sunscreen, SPF 30+ Sunglasses 3-5 Medium -Sunscreen, SPF 30+ Sunglasses, Hat 6-7 High -Sunscreen, SPF 30+ Sunglasses, Hat, and Seek Shade 8-10 Very High -Sunscreen, SPF 30+ Sunglasses, Hat, and Seek Shade Limit Time: 10am-4pm 11+ Extreme -Sunscreen, SPF 30+ Sunglasses, Hat, and Seek Shade Stay Inside: 10am-4pm
The infrared spectrum is further sub divided into five categories:
1. Near Infrared (cellphone, remote control) 2. Short wavelength Infrared (cell sites/tower) 3. Mid wavelength Infrared (spacecraft?) 4. Long Wavelength Infrared (human body color) 5. Far Infrared (outer space)
X-Ray Trivias
1. The 'x' means unknown. -Roentgen named his discovery X-strahlen—Strahlen being German for "beam" or "ray," and "x" being used in mathematics to indicate an unknown quality 2. X-ray helped in the discovery of the DNA structure. -Rosalind Franklin, a British researcher, photographed the first images showing our DNA's structure through X-ray crystallography. 3. They can kill cancer. -Narrowly focused beams of x-rays are used in some forms of cancer radiotherapy to destroy tumor tissues. 4. They've helped us see into space. -In 1999, NASA deployed their Chandra X-ray Observatory aboard the Space Shuttle Columbia. 5. X-ray can't pass through lead. -Lead can effectively stop x-rays because of its high density and high atomic number.
There are four main electromagnetic interactions:
1. The force of attraction or repulsion between electric charges is inversely proportional to the square of the distance between them. 2. Magnetic poles come in pairs that attract and repel each other, much as electric charges do. 3. An electric current in a wire produces a magnetic field whose direction depends on the direction of the current. 4. A moving electric field produces a magnetic field, and vice versa.
Applications of Gamma Rays
1. Treatment of cancerous cell in our body without the use of the surgery Medical Treatment -Gamma rays kill bacteria and cancer cells, they have been used to kill certain types of cancer. -Used to sterilize medical equipment. 2. Used in Industries to kill harmful bacteria organism like yeast. Food Industry Application -Gamma rays are used to preserve food and irradiate decay causing bacteria. Irradiated food- Gamma rays kill microbes and are used to sterilize food so that it will keep fresh for longer. 3. Sterilize medical instruments 4. Detect brain and heart abnormalities 5. To look for cracks in pipe and aircraft parts Industrial Application -detect defects in metal castings and find weak spots in welded structures. -Used to examine airport luggage and cargo.
History of Gamma Rays
1900 -Paul Villard discovers a third component of radioactivity, which become known as gamma rays. 1903 -Ernest Rutherford named this radiation gamma rays based on their relatively strong penetration of matter.
The Microwave Oven
1947 - the microwave oven was accidentally made BY Percy Spencer, an engineer who was working at a radiation laboratory. He investigated a radar because he noticed that a candy bar in his pocket melted. heated popcorn kernels, which became the world's first microwaved popcorn. the first produced microwave oven was about 6 feet tall and weighed around 750 pounds. The price tag on these ovens was about $5000 per piece. 1967 - the first microwave oven that was both somewhat affordable ($495) and reasonably sized (counter-top model) became available.
X-RAYS
8 November 1895 - a type of electromagnetic radiation with higher energy than visible light and lower energy than gamma rays
Henri Becquerel
A French physicist working in Paris at the same time as Marie and Pierre Curie, is credited with discovering gamma rays In 1895, Roentgen discovered X-rays and shortly thereafter Becquerel discovered radioactivity of uranium salts. Paul Villard's main interest was in chemistry, which guided him into his studies of cathode rays, X-rays, and "radium rays."
What happens when electric and magnetic fields change?
A changing magnetic field creates a changing electric field. A current can be induced in a conducting loop if it is exposed to a changing magnetic field.
What is the relationship between electricity and magnetism?
A moving charged particle (electricity) creates a magnetic field.
IONIZING RADIATIONS
A type of high-energy radiation that has enough energy to remove an electron (negative particle) from an atom or molecule, causing it to become ionized. Ionizing radiation can cause chemical changes in cells and damage DNA.
What is the speed of EM waves?
All EM waves travel 300,000 km/sec in space. c = 3.00 x10_8 m/s EM waves usually travel slowest in solids and fastest in gases.
Properties of EM Waves
All matter contains charged particles that are always moving; therefore, all objects emit EM waves. The wavelengths become shorter as the temperature of the material increases. EM waves carry radiant energy.
AM and FM
Amplitude Modulation Frequency Modulation
Oscilloscope
An oscilloscope is a laboratory instrument commonly used to display and analyze the waveform of electronic signals.
How do moving charges create magnetic fields?
Any moving electric charge is surrounded by an electric field and a magnetic field.
Microwave Facts
Arno Penzias and Robert Wilson, scientists at Bell Labs, made an incredible discovery quite by accident: They detected background noise using a special low-noise antenna. they had serendipitously discovered the cosmic microwave background radiation. This radiation, which fills the entire universe, is a clue to its beginning, known as the Big Bang. Penzias and Wilson were awarded the 1978 Nobel Prize in physics for their discovery. The cosmic microwave background radiation has since been mapped with great accuracy by satellites.
Astronomy
Astronomers can look at an area of the sky that is dark in the visual part of the electromagnetic spectrum but find the area is extremely active in the infrared. Most objects that have any significant heat produce infrared waves, but not everything is hot enough to light up.
Negative Effects of Infrared
BURNs SKIN IRRITATION LOW BLOOD PRESSURE EYE DAMAGE DEHYDRATION
USES OF X-RAY WAVES
Broken Bones, Airport Security, Radio Therapy, Engineering, Surgery, Industry
HAZARDS of RADIO WAVES
Cataracts, corneal edema, endothelial cell loss and retinal degeneration electroencephalogram indicate functional changes in the form of development of braking in the cortical cells when you have too much exposure on radio waves. outstretched hands, vegetative disorders (red persistent dermographism, acrocyanosis, rash and others)
Electromagnetic Theory Terms
Electricity- the flow of electric charge Electric Field - vector field representing force around a charged particle Magnetism- the force exerted by magnets that causes them to attract or repel each other. Magnetic Field- vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials.
Can a particle be a wave?
Electrons fired at two slits actually form an interference pattern similar to patterns made by waves Electrons fired at two slits actually form an interference pattern similar to patterns made by waves
DISCOVERY OF GAMMA RAYS
GAMMA RAYS WERE THE LAST KIND OF ELECTROMAGNETIC RADIATION TO BE DISCOVERED. PAUL VILLARD, A FRENCH SCIENTIST, WAS WORKING WITH A MATERIAL CALLED RADIUM, WHICH PRODUCED X-RAYS, BUT HE ALSO NOTICED THAT IT PRODUCED ANOTHER KIND OF ELECTROMAGNETIC RADIATION WITH A MUCH HIGHER ENERGY. THIS NEW KIND OF ELECTROMAGNETIC ENERGY WOULD GO RIGHT THROUGH HIS EXPERIMENT EVEN WHEN THE X-RAYS HAD BEEN STOPPED.
HAZARD OF INFRARED RADIATION
GREEN HOUSE EFFECT The trapped radiation causes increased temperatures and changes in weather that could be harmful to people and animals.
Heinrich Hertz 1857-1894
Heinrich Hertz was a brilliant German physicist and experimentalist who in 1888 demonstrated that the electromagnetic waves predicted by James Clerk Maxwell actually exist. Hertz is also the man whose peers honored by attaching his name to the unit of frequency; a cycle per second is one hertz.
NATURAL SOURCES OF X-RADIATION
INCLUDE RADON GAS, OTHER RADIOISOTOPES, LIGHTNING, AND COSMIC RAYS IN EARLY 1896, X-RAYS WERE BEING UTILIZED CLINICALLY IN THE UNITED STATES FOR SUCH THINGS AS BONE FRACTURES AND GUNSHOT WOUNDS.
Hans Christian Oersted 1777-1851
In 1820, Oersted discovered by accident that electric current creates a magnetic field. Prior to that, scientists thought that electricity and magnetism were unrelated. Oersted also used a compass to find the direction of the magnetic field around a wire carrying current.
Can a wave be a particle?
In 1887, Heinrich Hertz discovered that shining light on a metal caused electrons to be ejected. Whether or not electrons were ejected depended upon frequency not the amplitude of the light! Remember energy depends on amplitude. Years later, Albert Einstein explained Hertz's discovery: EM waves can behave as a particle called a photon whose energy depends on the frequency of the waves.
Radio Frequency (RF)
Is a rate of oscillation in the range of about 3kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents that carry radio signals. is the frequency range used in radio, extending from around twenty thousand times per second (20 kHz) to around three hundred billion times per second (300 GHz).
James Clerk Maxwell 1831-1879
Maxwell's Theory of Electromagnetism Electricity and magnetism were once thought to be separate forces. However, in 1873, Scottish physicist James Clerk Maxwell developed a unified theory of electromagnetism. The study of electromagnetism deals with how electrically charged particles interact with each other and with magnetic fields.
Michael Faraday 1791-1867
Michael Faraday is credited with discovering electromagnetic induction on August 29, 1831. When Michael Faraday made his discovery of electromagnetic induction in 1831, he hypothesized that a changing magnetic field is necessary to induce a current in a nearby circuit. To test his hypothesis he made a coil by wrapping a paper cylinder with wire. He connected the coil to a galvanometer, and then moved a magnet back and forth inside the cylinder.
Microwave
Microwaves are a type of wave that is in between radio waves and infrared waves on the electromagnetic spectrum. Microwave frequencies can be as low as 300MHz and as high as 300GHz. Their wavelengths can range from one meter to one millimeter. Extremely high-frequency radio waves Wavelengths: ~1mm to 30mm Found between very high frequency and conventional radio waves Made by various types of transmitters
Discovery of Microwaves
Microwaves were first predicted by James Clerk Maxwell by the use of his equations. Heinrich Hertz proved the existence of microwaves by building a device that produced and detected microwave radiation.
Sources of UV Rays
Natural- Sunlight Artificial- UV lamp, Arc welding, Mercury vapor lamps
EM Theory's BIG FOUR
OERSTED - Discovered magnetic property of current carrying conductor FARADAY - Discovered induced current due to changing magnetic field MAXWELL - Predicted the existence of electromagnetic waves HERTZ - Demonstrated Electromagnetic waves and propagation
X-Ray Precautions
PREGNANT WOMEN SHOULD NOT HAVE X RAYS . BODY PARTS NOT BEING X RAYED SHOULD BE SHIELDED WITH A LEAD APRON ALTHOUGH UNNECESSARY EXPOSURE TO RADIATION SHOULD BE AVOIDED, THE LOW LEVELS OF RADIATION ONE IS EXPOSED TO DURING AN X RAY DOES NOT CAUSE HARM WITH A FEW EXCEPTIONS.
Paul Villard
Paul Villard's main interest was in chemistry, which guided him into his studies of cathode rays, X-rays, and "radium rays." Villard recognised them as being different from X-rays because the gamma rays had a much greater penetrating depth. He had discovered they were emitted from radioactive substances and were not affected by electric or magnetic fields.
LOW FREQUENCY EM RADIATION
RADIO WAVE, MICROWAVE, INFRARED
Microwave Hazards
Radiation can be harmful to living organisms Radiation Leakage Microwaves Change heart rates and blood Very harmful to newborn babies 93% nutrients present in the food are destroyed The human body cannot metabolize unknown byproducts Microwave products cause stomach and intestinal cancerous growth (tumor) Microwaves zap food nutrition Microwaves create *carcinogen?* in food Microwaves destroy breast milk and vitamin B-12 To humans- Microwave radiation can heat body tissue the same way it heats food. Exposure to high levels of microwaves can cause a painful burn. Two areas of the body, the eyes and the testes, are particularly vulnerable to RF heating because there is relatively little blood flow in them to carry away excess heat. Additionally, the lens of the eye is particularly sensitive to intense heat, and exposure to high levels of microwaves can cause cataracts. But these types of injuries - burns and cataracts - can only be caused by exposure to large amounts of microwave radiation. Microwaves Can Change Your Heart Rate Microwaves Can Change the Makeup of Your Blood Can caused headaches, fatigue, memory loss, impaired learning, brain damage, and dysfunction Increases your risk of impaired brain function and can affect our central nervous system (CNS) causing neurodegenerative diseases such as Alzheimer's (the most common form of dementia), cancer, and infertility.
What is a radio wave?
Radio waves are EM (Electromagnetic)waves that have wavelengths between 1 millimeter and 100 kilometers (or 300 GHz and 3 kHz in frequency). Radio waves are one of many forms of electromagnetic (EM) radiation, or waves -HAVE THE LONGEST WAVELENGTHS IN THE ELECTROMAGNETIC SPECTRUM. -HAVE WAVELENGTHS THAT RANGE FROM LESS THAN A CENTIMETER TO TENS OR EVEN HUNDREDS OF METERS. -RADIO WAVES ARE USED TO TRANSMIT RADIO AND TELEVISION SIGNALS. Radio waves of the standard AM broadcast band have longer wavelength (ranging from 180-550 meters) compared to the short radio waves for FM band (ranging from 2.8-3.4 meters).
Microwave Uses
Satellite Communications - can penetrate the atmosphere of the earth. Communication satellites travel around the earth at an altitude of 35,000 km above the equator. - M. signals are transmitted by an antenna to a satellite which amplifies and re-transmits the signal to an antenna in other parts of the world. Radar Radio detection and ranging. Microwaves have short wavelengths and are reflected by small objects. This property is used in radars. A radar system consists of an antenna, transmitter, and receiver. Television Transmission (Terrestrial Communication) - Microwaves are used to transmit television news coverage from mobile broadcast vehicles back to the station. The news crew can also set up a small antenna to send signals to a communication satellite. This is how news is broadcasted and watched live around the world. A cell phone is a radio transmitter and receiver that uses microwaves. Cellular phones depend on overlapping network of cells or areas of land several kilometers in diameter. Cooking Microwave Oven -In a microwave oven, foods absorb certain microwave frequencies very strongly. The microwaves penetrate the food being heated. -The microwaves heat food by causing water molecules in it to vibrate at very high frequencies and eventually turn to steam which heats your food.
Gamma Rays Detectors
Scintillation Detector Solid-state Detector Gas-filled Detector
Infrared Wave
The infrared waves are all around us and earth is full of infrared waves. These waves are emitted by anything which is capable of emitting heat.
History of Microwave
The microwave oven is one of the great inventions of the 20th century. In 1947, the microwave oven was accidentally made by Percy Spencer, an engineer. The first produced microwave oven was about 6ft tall and weighed 70 pounds and was $5000 piece In 1967, the price become affordable about $495
Ultraviolet Rays
The portion of the electromagnetic spectrum extending from the violet, or short-wavelength, end of the visible light range to the X-ray region. Ultraviolet simply means "beyond light", in this case the visible type that we humans can see. It is also called "black light" due to it being invisible.
USES OF INFRARED
Thermography Thermography uses infrared technology to determine the relative temperature of objects by detecting the amount of radiation they are producing. Meteorology Weather satellites use infrared technology to determine water temperature and cloud formations. Art History Infrared lights can be used to look under layers of painting to determine if there are older layers underneath. Heating Infrared can also be used to create and conduct heat. Infrared saunas have become popular in the physical therapy field. Communications Some of these wavelengths are used in optical communication to carry the information from one place to another. It is also used to have a channel for short range communication. Tracking Technology Infrared can be used in tracking technology; objects, commonly missiles, can be sent to follow a target based on their infrared radiation.
UV Rays subtypes
Ultraviolet A - UVA - 315-400 - Long-wave black light not absorbed by the ozone layer Ultraviolet B - UVB - 280-315 - Medium-wave, mostly absorbed by the ozone layer Ultraviolet C - UVC - 100-218 - Short0wave, germicidal, completely absorbed by the ozone layer and atmosphere
HIGH FREQUENCY EM RADIATIONS
Ultraviolet, X-Ray, Gamma Rays
Can I put metal objects in the microwave?
Unlike plastics and ceramics, metals reflect a microwave (which means they can't pass through). So if you put your microwave meal in a metal dish, it won't allow it to heat up correctly. Thinner pieces of metals, for example foils, can act as an antenna, which can create sparks. This is extremely dangerous and could cause your microwave to set on fire.
Wave relations
Wave frequency and wavelength are inversely related EM wave velocity in vacuum is constant
Wave Terminologies
Wavelength= distance from crest to crest or trough to trough. Frequency= number of wavelengths that pass a given point in 1 s. As frequency increases, wavelength becomes shorter.
Making Electromagnetic Waves
When an electric charge vibrates, the electric field around it changes creating a changing magnetic field.
History of X-Ray
Wilhelm Roentgen 27 March 1845 - 10 February 1923 Cathode tube - a glass container in which a beam of electrons lights up a fluorescent window IN LATE 1895, A GERMAN PHYSICIST, W. C. ROENTGEN WAS WORKING WITH A CATHODE RAY TUBE IN HIS LABORATORY. HE EVACUATED THE TUBE OF ALL AIR, FILLED IT WITH A SPECIAL GAS, AND PASSED A HIGH ELECTRIC VOLTAGE THROUGH IT. THROUGH ADDITIONAL EXPERIMENTS, HE ALSO FOUND THAT THE NEW RAY WOULD PASS THROUGH MOST SUBSTANCES CASTING SHADOWS OF SOLID OBJECTS ON PIECES OF FILM. HE NAMED THE NEW RAY X-RAY, BECAUSE IN MATHEMATICS "X" IS USED TO INDICATED THE UNKNOWN QUANTITY.
HOW X- RAYS WORK
X -RAYS PASS EASILY THROUGH AIR AND SOFT TISSUE OF THE BODY. WHEN THEY ENCOUNTER MORE DENSE MATERIAL, SUCH AS A TUMOR, BONE, OR A METAL FRAGMENT, THEY ARE STOPPED. DIAGNOSTIC X RAYS ARE PERFORMED BY POSITIONING THE PART OF THE BODY TO BE EXAMINED BETWEEN A FOCUSED BEAM OF X RAYS AND A PLATE CONTAINING FILM. THE X RAYS THAT PASS THROUGH THE BODY STRIKE THE PHOTOGRAPHIC PLATE AND INTERACT WITH SILVER MOLECULES ON THE SURFACE OF THE FILM. ONCE THE FILM PLATES HAVE BEEN PROCESSED, DENSE MATERIAL SUCH AS BONE SHOWS UP AS WHITE, WHILE SOFTER TISSUE SHOWS UP AS SHADES OF GRAY, AND AIRSPACES LOOK BLACK. A RADIOLOGIST, WHO IS A PHYSICIAN TRAINED TO INTERPRET DIAGNOSTIC X RAYS, EXAMINES THE PICTURES AND REPORTS TO THE DOCTOR WHO ORDERED THE TESTS.
