Introduction to the Electromagnetic spectrum
The electromagnetic spectrum is a group of transverse waves that do not require a medium to travel through and it is divided up into sections based on frequency/wavelength and how each section is produced. In a vacuum each member has the same speed of 3xE8m/s but the speeds are different for each member when they travel through different media.
Electromagnetic radiation (EM radiation or EMR) is a form of energy emitted and absorbed by charged particles which exhibits wave-like behaviour as it travels through space.
The electromagnetic waves that compose electromagnetic radiation can be imagined as a self-propagating transverse oscillating wave of electric and magnetic fields. This diagram shows a plane linearly polarized EMR wave propagating from left to right. The electric field is in a vertical plane and the magnetic field in a horizontal plane (oscillating in phase) and both are perpendicular to the direction of energy and wave propagation. The two types of fields in EMR waves are always in phase with each other, and no matter how powerful, have a ratio of electric to magnetic intensity which is fixed and never varies.
The electromagnetic spectrum is continuous in that there is no break with each section. Because of this each section of the spectrum can share frequencies and wavelengths with their neighbours (such as X-rays and gamma rays) and what separates them out is how they are produced.
Region of the spectrum
Main interactions with matter
Collective oscillation of charge carriers in bulk material (plasma oscillation). An example would be the oscillation of the electrons in an antenna.
Microwave through far infrared
Plasma oscillation, molecular rotation
Molecular vibration, plasma oscillation (in metals only)
Molecular electron excitation (including pigment molecules found in the human retina), plasma oscillations (in metals only)
Excitation of molecular and atomic valence electrons, including ejection of the electrons (photoelectric effect)
Excitation and ejection of core atomic electrons, Compton scattering (for low atomic numbers)
Energetic ejection of core electrons in heavy elements, Compton scattering (for all atomic numbers), excitation of atomic nuclei, including dissociation of nuclei
High-energy gamma rays
Creation of particle-antiparticle pairs. At very high energies a single photon can create a shower of high-energy particles and antiparticles upon interaction with matter.
Radio waves and microwaves by Pameer Saeed
This report will describe, what is an electromagnetic wave and it will also describe two different types of electromagnetic waves with their applications.
Scientists have found that many types of wave can be arranged together like the notes on a piano keyboard, to form a scale. The low notes have a low frequency and a long wavelength. And the ‘high notes’ have a high frequency and a short wavelength.
When we say "wave", we think of a wave on the sea. There, it’s nice and obvious what’s going on the surface of the sea is vibrating up and down. With a sound wave, it’s the air particles that are vibrating. And Electromagnetic waves are vibrations of magnetic and electric fields. They don’t need air in order to travel. They don’t need anything to be there at all. 
Electromagnetic waves are transverse waves. Their electric field and magnetic field vibrate at right angles to one another.
Radio waves have the longest wavelength in the electromagnetic spectrum with a wavelength approximately greater than 1xE-1 m. Heinrich Hertz proved their existence in the late 1880s using a spark gap attached to an induction coil and a separate spark gap on a receiving antenna. When waves created by the sparks of the coil transmitter were picked up by the receiving antenna, sparks would jump its gap as well. Hertz showed in his experiments that these signals possessed all the properties of electromagnetic waves. 
How radio waves are made?
Radio waves are made by various types of transmitter, depending on their wavelength. They are also given off by stars, sparks and lightning, which is why we hear interference on the radio in a thunderstorm.
Applications of radio waves:
Radio waves have the lowest frequencies in the electromagnetic spectrum, and are used mainly for communication.
Radio waves are divided into:-
- Long Wave, around 1~2 km in wavelength. “The radio station "Atlantic 252" broadcasts here.”
- Medium Wave, around 100m in wavelength, used by BBC Radio 5 and other "AM" stations.
- VHF, which stands for "Very High Frequency" and has wavelengths of around 2m. This is where you find stereo "FM" radio stations, such as BBC Radio 1 and further up the VHF band are civilian aircraft and taxis.
- UHF stands for "Ultra High Frequency", and has wavelengths of less than a meter. It’s used for Police radio communications, television transmissions and military aircraft radios – although military communications are now mostly digital and encrypted. 
Microwaves are a portion or band of the electromagnetic spectrum found at the higher frequency end of the radio spectrum, but they are commonly distinguished from radio waves because of the technologies used to create and access them. Their wavelength is between 1xE-3 and 1xE-1, which means a couple of centimetres. Different wavelengths of microwaves (grouped into sub-bands) provide different information to scientists.
Medium length (C-band) microwaves penetrate through clouds, dust, smoke, snow and rain to reveal the earth’s surface. “L-band microwaves like those used by a Global Positioning System (GPS) receiver in our cars, can also penetrate the canopy cover of forests to measure the soil moisture of rain forests. Most communication satellites use C-, X- and Ku-bands to send signals to a ground station.”
How Microwaves are made?
Microwaves are basically extremely high frequency radio waves, and are made by various types of transmitter.
In a mobile phone, they’re made by a transmitter chip and an antenna and in a microwave oven they’re made by a magnetron. Stars also give off microwaves too.
Applications of microwaves:
Microwaves cause water and fat molecules found in food to vibrate, which makes them hot. Microwaves are used to cook many types of food.
Mobile phones use microwaves, as they can be generated by a small antenna, which means that the phone doesn’t need to be very big. The drawback is that, being small, they can’t put out much power, and they also need a line of sight to the transmitter. This means that mobile phone companies need to have many transmitter towers if they’re going to attract customers.
Microwaves are also used by fixed traffic speed cameras, and for radar, which is used by aircraft, ships and weather forecasters.
The most common type of radar works by sending out bursts of microwaves, detecting the "echoes" coming back from the objects they hit, and using the time it takes for the echoes to come back to work out how far away the object is. 
Microwave Radio Frequencies and Earth orbiting Satellites are causing Global Warming!
Since the late 1950’s, Microwave Radio Frequencies have become the dominant form of communication for TV’s, Cell Phones, Weather Stations, and a host of other uses. Each of these companies having millions of subscribers satellite antennas and Earth antennas transmit UHF and higher microwave frequencies all over the planet. Just like a Vacuum tube in old electronic technology, microwaves are insulated by the vacuum of space. Because the vacuum of space acts as an insulator, microwave radio frequencies are scattered through our atmosphere at an accelerated rate.
The Earth is a rotating electromagnetic field containing a dielectric material called water. Sending oscillating microwave radio frequencies through an electromagnetic field into a dielectric material, such as water, creates radio frequency heating (also called RF heating) at the molecular level of water. Because Earth’s electromagnetic field points directly towards the North Pole and the Earth’s atmosphere is circulating the warmed air through ordinary convection towards the North pole, the radio frequency heating is guided directly towards the Polar Ice Caps. This is melting the Polar Ice caps. Since our atmosphere is made of water and the Earth is covered with water and ice, microwave radio frequencies pass through our atmosphere, oceans, and ice caps. Because the wattage levels are minimal, warming is caused by a constant flow of waves that are never turned off. It is similar to cooking food in the microwave oven at a lower wattage setting. It takes longer, but still achieves its goal, Global Warming!!! 
Tour of the Electromagnetic spectrum
- Author: Ginger Butcher
- Design and illustration: Jenny Mottar
- Copy editing: C. Claire Smith
- Web address: www.nasa.gov
§ Book release date: June 6, 2010
§ Page 10 and 12
Discover, The Magazine Of Science, Technology And The Future Article By Breanna Draxler ( February 6, 2013)
Wired Magazine Future Science, Culture & Technology News
Article: Activate your genes with radio waves
By Madhumita Venkataramanan (This article was taken from the September 2012 issue of Wired magazine.)
Infrared Radiation by Matthew Kelly
William Herschel, an amateur astronomer famous for the discovery of Uranus in 1781, made an important discovery in 1800. He wondered if Newton’s discovery that sunlight could be separated into a visible spectrum with refraction through a glass prism might contain other wavelengths that produce the heat that warms us, so he repeated Newton’s experiment to create a spectrum and measured the temperatures of the different colours. He used three thermometers with blackened bulbs and placed one bulb in each colour while the other two were placed outside the spectrum as control. He found that the bulb placed outside of the spectrum near red showed a temperature increase absent from other parts of the spectrum.
Frederick William Herschel. Born: 15 November 1738 in Hanover, Brunswick-Lüneburg. Died: 25 August 1822(1822-08-25) (aged 83) in Slough, England. Nationality: German; later British. Fields of interest included Astronomy and music. Known for the discovery of Uranus, discovery of infrared radiation and deep sky surveys. Notable awards include the Copley Medal. Signature:
Infrared is the name of the region discovered by Herschel and can be shown to be an electromagnetic wave and to have a wavelength rather longer than that of visible light. In fact the infrared region of the spectrum extends from about 750 nm to some 400 000 nm (0.4mm)
All bodies at all temperatures emit some infrared radiation, the intensity and wavelength allocation depending on the temperature of the object.
The above image shows a false colour image of two people taken with mid-infrared ("thermal") light.
At temperatures between about 523 and 773 K the radiation emitted is in the Infrared region of the electromagnetic spectrum. This radiation is invisible to the human eye but its detection is used in Earth weather satellites, in remote controls for televisions, astronomy and by the military in night vision.
The above image shows hyperspectral thermal infrared emission measurement, an outdoor scan in winter conditions, ambient temperature −15°C, image produced with a Specim LWIR hyperspectral imager. Relative radiance spectra from various targets in the image are shown with arrows. The infrared spectra of the different objects such as the watch clasp have clearly distinctive characteristics. The contrast level indicates the temperature of the object.
The above IR Satellite picture was taken on the 15th October 2006. A frontal system can be seen in the Gulf of Mexico with embedded Cumulonimbus cloud. Shallower Cumulus and Stratocumulus can be seen off the Eastern Seaboard.
The above image shows active-infrared night vision: the camera illuminates the scene at infrared wavelengths invisible to the human eye. Despite a dark back-lit scene, active-infrared night vision delivers identifying details, as seen on the display monitor.
The above image shows an Infrared light from the LED of an Xbox 360 remote control as seen by a digital camera.
The above image is an infrared space telescope image where blue, green and red correspond to 3.4, 4.6, and 12 micron wavelengths respectively.
For more information see:
Visible Light is part of the electromagnetic spectrum. All electromagnetic waves can be considered as forms of light, but only a small range of them are visible to us; these are between certain wavelengths which our eyes can perceive.
Visible Light is produced by oscillations. They are transverse waves, which mean that their oscillations occur at right angles to their apparent direction of propagation.
Above is a diagram to show the frequency and wavelength of the visible light in the electromagnetic spectrum. As you can see it is between Infrared and Ultraviolet radiation.
The diagram above shows the approximate frequency and wavelength of each part of the visible spectrum. You might notice that indigo is missing from the list. This is because some scientists think that Newton invented it because he liked the number seven.
The colour of the visible light has been shown to have an effect on us humans. The most notable effect is red making us feel warm and blue making us feel cold.
It can affect how well we sleep and make us happy or sad. It can make us feel safe.
Different types of lighting are used in advertising and even identify political parties.
Visible Light has a very interesting history; it first began in the 17th century with Newton observing sunlight passing through a glass prism and seeing different colours as a result which made him think that light was made up of particles of different colours.
In the 19th century, Thomas Young observed that light was not made up of particles but in fact was actually a wave. He then measured the wavelengths of the different colours of light in 1802.
In 1810, Johann Wolfgang von Goethe (more famous for his literary works) published his “Theory of Colours”, which he considered his most important work. In it, he characterized colour as arising from the dynamic interplay of light and darkness through the mediation of a turbid medium. In 1816, Schopenhauer went on to develop his own theory in “On Vision and Colours” based on the observations supplied in Goethe’s book. After being translated into English by Charles Eastlake in 1840, his theory became widely adopted by the art world, most notably J. M. W. Turner. Goethe’s work also inspired the philosopher Ludwig Wittgenstein, to write his “Remarks on Colour”. Goethe was vehemently opposed to Newton’s analytic treatment of colour, engaging instead in compiling a comprehensive rational description of a wide variety of colour phenomena. Although the accuracy of Goethe’s observations does not admit a great deal of criticism, his theory’s failure to demonstrate significant predictive validity eventually rendered it scientifically irrelevant. Goethe was, however, the first to study the physiological effects of colour, and his observations on the effect of opposed colours led him to a symmetric arrangement of his colour wheel, ‘for the colours diametrically opposed to each other… are those which reciprocally evoke each other in the eye. (Goethe, Theory of Colours, 1810). In this, he anticipated Ewald Hering’s opponent colour theory (1872).
The above picture shows the light spectrum, from Theory of Colours. Goethe observed that with a prism, colour arises at light-dark edges, and the spectrum occurs where these coloured edges overlap.
Visible Light is used by plants for photosynthesis which is the process that uses up carbon dioxide and produces oxygen and glucose. Visible light is used to break down plastics and polymers. It can also be used to bleach fabric.
There are many benefits of Visible Light; firstly, it allows us to see different colours and the beauty of the nature and the world. However there are also risks of visible light such as overexposure which causes damage to the human eye, visible light also damages films used for film photography and movies and causes deterioration to materials such as old documents and photos.
Image for electromagnetic spectrum – http://cnx.org/content/m15131/latest/
Table for frequency and wavelength – http://en.wikipedia.org/wiki/Visible_spectrum
Edexcel AS PHYSICS BOOK
Ultra violet radiation by Manikandan Jeyakanthan
The discovery of UV radiation was associated with the observation that silver salts darkened when exposed to sunlight. In 1801, the German physicist Johann Wilhelm Ritter made the hallmark observation that invisible rays just beyond the violet end of the visible spectrum darkened silver chloride-soaked paper more quickly than violet light itself. He called them "oxidizing rays" to emphasize chemical reactivity and to distinguish them from "heat rays," discovered the previous year at the other end of the visible spectrum. The simpler term "chemical rays" was adopted shortly thereafter, and it remained popular throughout the 19th century. The terms chemical and heat rays were eventually dropped in favour of ultraviolet and infrared radiation, respectively.
The discovery of the ultraviolet radiation below 200 nm, named vacuum ultraviolet because it is strongly absorbed by air, was made in 1893 by the German physicist Victor Schumann.
Above is a picture of Johann Wilhelm Ritter
Born: December 16, 1776 in Samitz, Silesia, Holy Roman Empire
Died: January 23, 1810 (aged 33) in Munich, Bavaria
Known for Electrochemistry and Ultraviolet light
What is Ultraviolet radiation
Ultraviolet (UV) radiation is similar to visible light in all physical aspects, except that it does not enable us to see things. The light that enables us to see things is referred to as visible light and is composed of the colours we see in a rainbow. The ultraviolet region starts right after the violet end of the rainbow.
In scientific terms, UV radiation is electromagnetic radiation just like visible light, radar signals and radio broadcast signals. Electromagnetic radiation is transmitted in the form of waves. The waves can be described by their wavelength or frequency and their amplitude (the strength or intensity of the wave). Wavelength is the length of one complete wave cycle. For radiation in the UV region of the spectrum, wavelengths are measured in nanometres (nm), where 1 nm = one millionth of a millimetre.
What are some sources of ultraviolet radiation?
Sunlight is the greatest source of UV radiation. Man-made ultraviolet sources include several types of UV lamps, arc welding apparatus, and mercury vapour lamps.
The above picture shows that electric arcs produce UV light, and arc welders must wear eye protection to prevent welder’s flash.
The picture above shows a low pressure mercury vapour discharge tube flooding the inside of a hood with shortwave UV light when not in use, sterilizing microbiological contaminants from irradiated surfaces.
UV radiation is widely used in industrial processes and in medical and dental practices for a variety of purposes, such as killing bacteria, creating fluorescent effects, curing inks and resins, phototherapy and sun tanning. Different UV wavelengths and intensities are used for different purposes.
What are some health effects of exposure to UV radiation?
Some UV exposure is essential for good health. It stimulates vitamin D production in the body. In medical practice, UV lamps are used for treating psoriasis (a condition causing itchy, scaly red patches on the skin) and for treating jaundice in new-born babies.
Excessive exposure can damage the skin and the eyes. The severity of the effect depends on the wavelength, intensity, and duration of exposure.
Effect on the skin
The shortwave UV radiation (UV-C) poses the maximum risk. The sun emits UV-C but it is absorbed in the ozone layer of the atmosphere before reaching the earth. Therefore, UV-C from the sun does not affect people. Some man-made UV sources also emit UV-C. However, the regulations concerning such sources restrict the UV-C intensity to a minimal level and may have requirements to install special guards or shields and interlocks to prevent exposure to the UV.
The medium wave UV (UV-B) causes skin burns and darkening of the skin. Prolonged exposures increase the risk of skin cancer.
How do you protect yourself from UV radiation?
UV radiation is invisible and therefore does not stimulate the natural defences of the eyes. Workers must use eye and skin protection while working with UV radiation sources which present the potential of eye harmful exposure. The selection of eye protection depends on the type and intensity of the UV source. UV radiation is easily absorbed in a variety of materials. Shielding is usually easy to design. Mercury lamps and metal halide lamps have an outer glass cover to stop UV radiation, and are designed such that if the outer glass is broken, the lamp ceases to function.
What can you do to protect yourself from UV radiation from the sun?
· Ways to limit exposure the sun’s UV radiation include avoiding working in the sun wearing protective clothing and hats, and applying sunscreens.
· Protective clothing can include long pants, hats, and long-sleeved shirts. Some newer, sun-resistant fabrics are more efficient in blocking UV radiation.
1) The Internet for finding about “UV radiation”
2) Book to find out about “What are some health effects of exposure to UV radiation?”
SOURCE – Ecosystems, Evolution and Ultraviolet Radiation, writer – Charles Cockell, written in 2001.
3) Magazine – Nature, article – An ultraviolet-radiation-independent pathway to melanoma carcinogenesis in the red hair/fair skin background
X-Rays by Aslam Sookia
This report is on x-rays, which are part of the electromagnetic spectrum.
Electromagnetic waves are a form of energy emitted and absorbed by charged particles which travel at the speed of light (3xE8 m/s).
X-radiation is called Röntgen radiation, after Wilhelm Röntgen, who discovered it (although he wasn’t the first to have observed their effects), and named it ‘X’ because it was unknown.
Wilhelm Conrad Röntgen Born: 27 March 1845 in Lennep, Rhine Province, Germany Died: 10 February 1923 (aged 77) in Munich, Germany Nationality: German Fields: Physics and X-ray astronomy Institutions: University of Strassburg, Hohenheim, University of Giessen, University of Würzburg and University of Munich Alma mater: ETH Zurich and University of Zurich Doctoral advisor: August Kundt Known for X-rays Notable awards: Nobel Prize in Physics (1901)
Above left: Hand mit Ringen (Hand with Rings): print of Wilhelm Röntgen‘s first "medical" X-ray, of his wife’s hand, taken on 22 December 1895 and presented to Ludwig Zehnder of the Physik Institut, University of Freiburg, on 1 January 1896. Above right: Mrs. Hare’s plated broken wrist.
X-rays have a wavelength of 0.01-10 nanometres and a frequency of 3xE16 (30petahertz) – 3xE19 (30exahertz).
X-rays are made when high energy electrons are shot at a metal and collide with the nuclei of the metal atom. The metal used is usually tungsten or a metal with a high melting point because the bombardment of electrons produces a lot of heat.
X-rays are able to penetrate materials with light atoms (i.e flesh), and are absorbed by materials with heavier atoms (i.e metal).
When humans undergo x-ray examinations, the soft tissue isn’t able to absorb the x-rays, so they pass straight through. Bones are able absorb the x-rays because they’re made of calcium.
Behind the part being examined there is a special film. The black areas are where the x-rays have passed through the human tissues and onto the film and the white/not black areas are where the x-rays haven’t hit because they were absorbed by the x-rays.
Uses of X-rays
X-rays are used for many things.
Detecting disease in teeth.
Locating bullets or other foreign objects in bodies.
Examining broken bones.
Inspecting canned goods and other packaged products
Airplane and automobile parts, rubber goods, plastics, metal castings, and a variety of other products.
Characteristic rays are used to analyse metal alloys, paint pigments, and other substances.
Other uses of X-rays are in X-ray machines, where the x-rays are used to check the contents of bags and to find any dangerous items.
Dangers of x-rays
X-rays have high energy, so they are able to turn atoms into ions by knocking off electrons.
X-rays can mutate, and kill living cells and must be used with care.
Improper use can cause severe burns, cancer, leukaemia and cataracts.
They can also speed aging, reduce immunity and bring about disastrous changes in the reproductive cells.
The effects of X-rays are cumulative, so a few small doses over a few years are the same as a big, one off dose.
A chest radiograph of a female, demonstrating a hiatus hernia
Head CT scan (transverse plane) slice -– a modern application of medical radiography
Edexcel AS physics book.
Gamma Radiation by Alfie Mussett
A gamma ray is defined as one of the many kinds of waves on the electromagnetic spectrum, and as such is itself an electromagnetic wave. But what is an electromagnetic wave? Put simply, an electromagnetic wave is the combination of an electric wave and a magnetic wave moving through space. The logic being that a magnet could produce a current to flow in a wire and a current flowing in a wire can produce a magnetic field, a combination of the two producing a self-sustaining wave.
This having to do with the way the two fields vary in space and time. Which can be best explained by this diagram in which E means "Electric field" and H means "magnetic field" and Z refers to the "direction of travel"
The waves being produced by an oscillating electric charge, often an electron, which in turns sets up an electric field, which then results in the creation of a magnetic field that then sustains the electric field which then sustains the magnetic field. So, in this way an electromagnetic wave can be referred to as a self-sustained, self-propagating wave.
Gamma rays specifically are produced by a number of means, but the most common means is that of radioactive decay. Radioactive decay is a process by which unstable nuclei will decompose to form a different nucleus and during this it gives off radiation in the form of the high energy waves we call gamma radiation.
Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, while studying radiation emitted from radium.
Born: 28 September 1860 in Saint-Germain-au-Mont-d’Or Died: 13 January 1934 (aged 73) in Bayonne Known for the discovery of Gamma Rays
Different electromagnetic waves are distinguished by their differing wavelengths but they all possess similar characteristics, like being able to travel without a medium, so they can all travel through a vacuum. The wavelength and frequency range that concerns gamma rays are electromagnetic waves with a wavelength shorter than 1 x E-11 metres and conversely, frequencies greater than 3×1019 hertz. Due to energy being proportional to the frequency, which is in turn inversely proportional to the wavelength, gamma rays have extremely high energy for electromagnetic waves, coming in at energy levels greater than 2xE-14 Joules.
Gamma rays find many uses due to its properties; it finds one particularly destructive use in the atomic bomb, where exploitation of the unstable atoms that produce gamma rays are used for massive damage.
Gamma rays are emitted during radioactive decay processes such as those found in nuclear explosions.
They also have medical uses; one of these medical uses is the treatment of brain tumors. Medical physicist Ian Paddick said "the gamma rays produce a highly focused radiation dose inside the head", and this can be utilised to kill off malignant cells by focusing this dose on them.
From this, we can conclude that gamma rays are a notable extreme on the electromagnetic spectrum, the highest energy wave on said spectrum has its destructive properties used for both the hindrance and benefit of people around the world.
Gamma-ray image of a truck with two stowaways taken with a VACIS (vehicle and container imaging system)
Name: Edexcel AS Physics
Author(s): Miles Hudson, Patrick Fullick
Citation: James Clerk Maxwell
Type: Textbook Page(s): 102
Name: Transmission and Propagation of Electromagnetic Waves
Author(s): Kenneth Frederick Sander, Geoffrey Alexander Leslie Reed
Type: Book Page(s): 9
Name: Nuclear Stability and Radioactive Decay
Name: Regions of the Electromagnetic Spectrum
Name: Gamma Rays Treat Brain Tumours
Author(s): N/A Citation: Ian Paddick Type: Video Clip