Practical Applications of EM Spectrum PDF

 Practical Applications of EM Spectrum The Electromagnetic Spectrum v. Visible Microwave Light RADIO WAVES RADIO WAVES v Radio waves have the longest wavelengths in the electromagnetic spectrum. v They are used to transmit...

 Practical Applications of EM Spectrum The Electromagnetic Spectrum v. Visible Microwave Light RADIO WAVES RADIO WAVES v Radio waves have the longest wavelengths in the electromagnetic spectrum. v They are used to transmit radio and television signal. RADIO WAVES v The transmission and reception of radio waves is dependent on oscillating charges. v When these radio waves encounter the antenna system of a radio receiver, small electric oscillations are set up in the antenna in synchronization with their own vibrations. RADIO WAVES v Radio development began as a wireless telegraphy, a historical term for early radio telegraph communications techniques and practices, particularly those used during the first three decades of radio (1887 to 1920). v As early as 1790s, the first fixed semaphore system (visual telegraphy) was developed in Europe, but it was not until the 1830s that electrical communication system has started to appear. RADIO WAVES v One of the early experiments in electrical telegraphy was an electrochemical telegraph created by Samuel Thomas von Sommering in 1809. v Sir Charles Wheatstone and Sir William Fothergill Cook constructed the first commercial electrical telegraph in England, while Samuel Morse was also doing his own version of the same technology on the other side of the Atlantic Ocean. RADIO WAVES v James Clerk Maxwell who showed mathematically that electromagnetic waves could propagate through free space. v Heinrich Rudolf Hertz and many others demonstrated, on a laboratory scale, radio wave propagation. v Nikola Tesla experimented on the transmission and radiation of radio frequency energy and proposed for the telecommunication of information. RADIO WAVES v In 1876, the conventional telephone was invented by Alexander Graham Bell. Years after its patent to Bell, the technology grew quickly, enabling telephone exchanges in every major city of the United States by the mid- 1880s. v In terms of radio and television, James Lindsay demonstrated wireless telegraphy within a two-mile distance using water as a transmission medium in 1854. RADIO WAVES v Around the turn of the century, the Slaby-Arco Wireless System was developed by Adolf Slaby and Georg von Arco. v In 1900, Reginald Fessenden made a weak transmission of voice over the airwaves. v Guglielmo Marconi was the first to demonstrate the application of radio in commercial, military, and marine communications and started a company for the development and propagation of radio communication services and equipment. In 1901, he conducted the first successful transatlantic experimental radio communications, which gave him the patent for the invention of radio and Nobel Prize in Physics in 1909. RADIO WAVES v In October 1925, Scottish inventor, John Logie Baird, was able to obtain moving pictures with halftone shades, which were, by most accounts, the first true television pictures. His device was known as the mechanical television, which was the basis of semi-experimental broadcasts done by the British Broadcasting Corporation beginning September 30, 1929 MICROWAVES Microwaves v Microwaves are basically extremely high frequency radio waves. v They have very short wavelengths ranging from approximately one millimeter to 30 centimeters. Microwaves v Microwaves are used in telecommunication, such as mobile phones. v They are also used by fixed traffic speed camera, in cooking food, and in radar to determine the range, altitude, direction, or speed of both moving and fixed objects, such as aircraft, ships, spacecraft, missiles, motor vehicles, and weather formations. INFRARED Infrared v Sir William Herschel discovered in 1800 the existence of infrared by passing sunlight through a prism. Infrared v Sir William Herschel discovered in 1800 the existence of infrared by passing sunlight through a prism. Infrared v Infrared is the EM radiation with a wavelength longer than that of visible light. v Microscopically, infrared light is typically emitted or absorbed by molecules when they change their rotational- vibrational movements. Infrared v Infrared is the EM radiation with a wavelength longer than that of visible light. v Microscopically, infrared light is typically emitted or absorbed by molecules when they change their rotational- vibrational movements. Infrared VISIBLE LIGHT Visible Light v Visible light is the portion of EM radiation that is visible to the human eye. Light waves are given off by anything that is hot enough to glow. We see the light waves as the colors of the rainbow. v Red has the longest wavelength and violet has the shortest. The other colors we see have frequencies and wavelengths intermediate between these two extremes. When all the waves are seen together, they make white light. ULTRAVIOLE T Ultraviolet v Ultraviolet is an EM radiation with a wavelength shorter than that of visible light, but longer than x-rays. v It is named because the spectrum consists of electromagnetic waves with frequencies higher than those that humans identify as the color violet. Ultraviolet v UV rays are used to prevent counterfeiters. Sensitive documents, such as credit cards and passports, include a UV watermark that is only seen under UV-emitting light. Visa stamps also contain large detailed seals which are invisible under the normal light but strongly visible under UV illumination. v UV is also helpful in crime scenes. Investigators can detect and locate semen, saliva, and other bodily fluids using high UV rays. Overexposure to UV may lead to skin cancer, melanoma, and eye problems, such as photokeratitis or sunburn of the cornea. X-RAYS X-rays v X-rays are high-energy waves which have great penetrating power and are used extensively in medical applications and in inspecting welds. v In many languages, X-radiation is called Röntgen radiation, after Wilhelm Conrad Röntgen, who named it as such in 1895, to signify an unknown type of radiation. X-rays v X-rays are high-energy waves which have great penetrating power and are used extensively in medical applications and in inspecting welds. v In many languages, X-radiation is called Röntgen radiation, after Wilhelm Conrad Röntgen, who named it as such in 1895, to signify an unknown type of radiation. X-rays v Overexposure to x-rays may lead to cancer such as leukemia. But the harmful side effects of x-ray scanning have also introduced radiotherapy, a medical procedure that is often used with chemotherapy, which uses very high frequency x-rays to destroy cancer cells. GAMMA RAYS Gamma Rays v Gamma rays are generated by radioactive atoms and in nuclear explosions, and are used in many medical applications. v They are more penetrating than x- rays. Gamma Rays v In spite of their cancer-causing properties, gamma rays are also used to treat some types of cancer. In the procedure called Gammта Knife Surgery, multiple concentrated beams of gamma rays are directed on the growth in order to kill the cancerous cells. The beams are aimed from different angles to focus the radiation on the growth while minimizing damage to the surrounding tissues. The Electromagnetic Spectrum v. The Electromagnetic Spectrum v. Visible Microwave Light The Electromagnetic Spectrum v. REVIEW ACTIVITY 2: 3 Es Activity 2: The 3Es Directions: Use the 3’s to complete the table. Types of EM Explain Examples Essence Waves 1. Radio Waves 2. Microwaves 3. Infrared 4. Visible Light 4. Ultraviolet 5. X-rays 6. Gamma Rays THANK YOU!