Submitted by:

Jacqueline DC. Aquino

Grade 10 – Love

Submitted to:

Mrs. Gina G. De Leon

Electromagnetic Waves and Electromagnetic Spectrum

Electromagnetic waves is the transmission of energy through a vacuum or using no medium. It is caused by the osscilation of electric and magnetic fields. These waves move at a constant speed of 3x108 m/s and often called electromagnetic radiation, light, or photons.

Electromagnetic waves has different types of waves and these types of waves are called electromagnetic spectrum.

Electromagnetic spectrum includes the order of increasing frequencies and decreasing wavelenght of waves: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

Radio Waves

Radio waves are a type of electromagnetic radiation with wavelengths longer than infrared ray. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths ranging from 1 millimeter (0.039 in) to 100 kilometers (62 mi). Radio waves are generated by radio transmitters and received by radio receivers. These naturally occurring waves are made by lightning, or by astronomical objects.

Radio waves were first predicted by mathematical work done in 1867 by Scottish mathematical physicist James Clerk Maxwell. Maxwell noticed wavelike properties of light and similarities in electrical and magnetic observations. His mathematical theory, now called Maxwell's equations, described light waves and radio waves as waves of electromagnetism that travel in space, radiated by a charged particle as it undergoes acceleration.

Uses / Applications

● Medicine: Radio waves are used to transmit the pattern of a heartbeat through a monitor at a patient's home to a nearby hospital. They are also used to radio the condition of a patient from an ambulance to a hospital. Radio waves are used in medicine when paramedics are dispatched to the scene where they are needed. The hospital can tell the paramedics the condition of the person so that the paramedics can prepare a medical treatment kit.

● Industry: Radios are also used in industry, mainly in the transportation business. Radio waves can also be used to provide communication on construction sites.

● Science: Radio waves from outside the earth are detected using in radio telescopes. Radio waves are picked up when they hit the antenna of the

radio telescope. The wave then goes to the tuner, then to the amplifier, and finally to the plotter.

● Consumer Goods: These waves are used in the remote control models which people buy. They are also used in radios, televisions and wireless headphones.

Microwaves

Microwaves are a form of electromagnetic radiation with wavelengths ranging from as long as one meter to as short as one millimeter; with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). Microwaves were first used for radar in WWII. (1939-1945) The development of microwaves is only one step of the gradual evolution of the concept and application of electromagnetic waves. Maxwell formulated a set of equations supporting all electromagnetic phenomena, which became known as Maxwell's equations. Hertz's experiment proved further generalizations and applications which led to the development of the microwave.

Uses / Applications

● Communication: Point-to-point (telecommunications), Microwave transmission and Satellite communications

● Navigation: Global Navigation Satellite Systems (GNSS) and Global Positioning

● Radar: Radar uses microwave radiation to detect the range, speed, and other characteristics of remote objects. Development of radar was accelerated during World War II due to its great military utility. Now radar is widely used for applications such as air traffic control, weather forecasting, navigation of ships, and speed limit enforcement.

● Radio astronomy: Most radio astronomy uses microwaves. Usually the naturally-occurring microwave radiation is observed, but active radar experiments have also been done with objects in the solar system, such as determining the distance to the Moon or mapping the invisible surface of Venus through cloud cover.

● Heating and power application: Microwave ovens became common kitchen appliances in Western countries in the late 1970s, following the development of less expensive cavity magnetrons. Water in the liquid state possesses many molecular interactions that broaden the absorption peak.

● Spectroscopy: Microwave radiation is also used to perform rotational spectroscopy and can be combined with electrochemistry as in microwave enhanced electrochemistry.

Infrared

Infrared (IR) is invisible radiant energy, electromagnetic radiation with longer wavelengths than those of visible light, extending from the nominal red edge of the visible spectrum at 700 nanometers (frequency 430 THz) to 1 mm (300 GHz) (although people can see infrared up to at least 1050 nm in experiments). Most of the thermal radiation emitted by objects near room temperature is infrared.

Infrared radiation was discovered in 1800 by astronomer Sir William 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's climate.

Uses / Applications

● Night vision: Infrared is used in night vision equipment when there is insufficient visible light to see.

● Thermography: Thermography (thermal imaging) is mainly used in military and industrial applications but the technology is reaching the public market in the form of infrared cameras on cars due to the massively reduced production costs.

● Hyperspectral imaging: A hyperspectral image, a basis for chemical imaging, is a "picture" containing continuous spectrum through a wide spectral range.

● Tracking: Infrared tracking, also known as infrared homing, refers to a passive missile guidance system, which uses the emission from a target of electromagnetic radiation in the infrared part of the spectrum to track it.

● Heating: Infrared radiation can be used as a deliberate heating source.

● Communications: IR data transmission is also employed in short-range communication among computer peripherals and personal digital assistants.

Visible Light

All electromagnetic radiation is light, but we can only see a small portion of this radiation—the portion we call visible light. Cone-shaped cells in our eyes act as receivers tuned to the wavelengths in this narrow band of the spectrum. Other portions of the spectrum have wavelengths too large or too small and energetic for the biological limitations of our perception.

As the full spectrum of visible light travels through a prism, the wavelengths separate into the colors of the rainbow because each color is a different wavelength. Violet has the shortest wavelength, at around 380 nanometers, and red has the longest wavelength, at around 700 nanometers.

Uses / Applications

● We use light to see things.

● Laser: Light waves can also be made using a laser. This works differently to a light bulb, and produces "coherent" light. Lasers are used in Compact Disc & DVD players, where the light is reflected from the tiny pits in the disc, and the pattern is detected and translated into sound or data. Lasers are also used in laser printers, and in aircraft weapon aiming systems.

Ultraviolet Waves

Ultraviolet (UV) light is an electromagnetic radiation with a wavelength from 400 nm to 100 nm, shorter than that of visible light but longer than X-rays. Though usually invisible, under some conditions children and young adults can see ultraviolet down to wavelengths of about 310 nm, and people with aphakia (missing lens) can also see some UV wavelengths. Near-UV is visible to a number of insects and birds.

UV radiation is present in sunlight, and is produced by electric arcs and specialized lights such as mercury-vapor lamps, tanning lamps, and black lights. Although lacking the energy to ionize atoms, long-wavelength ultraviolet radiation can cause chemical 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.

Uses/ Applications

● Our skin: When we expose our skin to UVB, it stimulates the production of vitamin D, which our bodies need. Window glass absorbs UVB, so people need to go outside to gain the benefit. However, too much exposure to UVB can cause skin cancers, so the aim is to find the optimum amount of exposure.

● Sterilisation and disinfection: UVB also helps us when we hang washing outside to dry, as some of the bacteria present in the washing are inactivated by exposure to UVB.

● Astronomy: Observing and recording the UV from astronomical objects such as planets in our solar system, stars, nebulae and galaxies enables us to gain extra information such as the temperature and chemical composition of these objects.

● Fluorescence and lighting: A number of substances are able to absorb the energy in UV light and immediately convert it into visible light. This effect is called fluorescence. The ink in highlighter pens contains a fluorescent dye that enables the ink to reflect vividly in sunlight and to glow strongly in the dark when a UV lamp is shone on it.

● Scanning: UV is used for detecting forged bank notes in shops.

X – Rays

X-radiation (composed of X-rays) is a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 100 eV to 100 keV. X-

ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. In many languages, X-radiation is referred to with terms meaning Röntgen radiation, after Wilhelm Röntgen, who is usually credited as its discoverer, and who had named it X-radiation to signify an unknown type of radiation.

Uses / Applications

● Radiographs: A radiograph is an X-ray image obtained by placing a part of the patient in front of an X-ray detector and then illuminating it with a short X-ray pulse. Bones contain much calcium, which due to its relatively high atomic number absorbs x-rays efficiently.

● Computed tomography: Computed tomography (CT scanning) is a medical imaging modality where tomographic images or slices of specific areas of the body are obtained from a large series of two-dimensional X-ray images taken in different directions.

● Fluoroscopy: Fluoroscopy is an imaging technique commonly used by physicians or radiation therapists to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope.

● Radiotherapy: The use of X-rays as a treatment is known as radiation therapy and is largely used for the management (including palliation) of cancer; it requires higher radiation doses than those received for imaging alone.

Gamma Rays

Gamma radiation, also known as gamma rays, and denoted by the Greek letter γ, refers to electromagnetic radiation of an extremely high frequency and therefore consists of high-energy photons. These rays typically have

frequencies above 10 exahertz (or >1019 Hz), and therefore have energies above 100 keV and wavelengths less than 10 picometers (10−12 meter), which is less than the diameter of an atom.

Gamma rays are ionizing radiation, and are thus biologically hazardous. They are classically produced by the decay of atomic nuclei as they transition from a high energy state to a lower state known as gamma 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" by Ernest Rutherford in 1903.

Uses / Applications

● It is used for treatment of cancerous cell in our body without the use of the surgery.

● It is used in industries to kill the harmful bacteria, organism like yeast etc.

● Like x – rays, it is also used to sterilize medical instruments.

● It is used to detect brain and heart abnormalities.

● Gamma rays are used by Engineers, since they can penetrate better than X-rays, to look for cracks in pipes and aircraft parts..

● One of the destructive use is their important role in development of the atomic bomb.

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