[Music] hi there in a previous lesson we were able to describe the different regions of electromagnetic waves in this video we will be citing examples of its practical applications by the way if you still haven't watched the previous lesson you can pause this video and watch that one first to better understand our topic today radiation is the transmission of energy in the form of waves or particles through space or through a material medium it may take such forms as light or tiny particles much too small to see visible light the ultraviolet light we receive from the sun and transmission signals for tv and radio communications are all forms of radiation that are common in our daily lives these are all generally referred to as non-ionizing radiation though at least some ultraviolet radiation is considered to be ionizing radiation particularly associated with nuclear medicine and the use of nuclear energy along with x-rays is ionizing radiation which means that the radiation has sufficient energy to interact with matter especially the human body and produce ions today conversations photos and even music can be transmitted through air over thousands of miles because of radio waves wireless communication has become possible through transmission and reception of these radio waves if you may recall radio waves can be transmitted through empty space [Music] radio waves have the longest wavelength in the electromagnetic spectrum they are produced by making electrons vibrate in an antenna medium and high frequency waves are used for broadcasting by local radio stations in a radio station sound is converted by a microphone into patterns of electric current variations called audio frequency or af signals high frequency radio waves called radio frequency or rf carriers can be modulated to match the electronic signal in amplitude modulation or am the amplitude of the radio waves changes to match that of the audio frequency signal this is used in standard broadcasting because it can be sent over long distances very high frequency waves provide a higher quality of broadcasting including stereo sound in this process instead of the amplitude of the rf carrier it is the frequency of the waves that changes to match that of the signal this is called frequency modulation or fm when the radio wave is received by the antenna of a radio or television the pattern is converted back to its original form the sound portions of most television broadcasts are carried as am waves while the picture portions are carried as fm waves they are used to transmit sound and picture information over long distances radio waves have a very wide range of wavelengths the whole region of the radio waves is divided into smaller regions of wave bands each waveband is allocated by law to a specific radio service did you know frequency is an important characteristic of radio waves am broadcast frequency is about 1 million hertz for example when you tune in to your favorite am radio station at 630 on the dial the radio is tuning to the radio wave with a frequency of 630 000 hertz on the other hand fm radio operates on 100 million hertz so when you tune in to 101.1 fm your radio is tuning to 101 million 100 000 hertz we know for a fact that radio waves travel in a straight line why then are we able to receive messages or information from other parts of the world let's take a short review of some facts we learn in earth science one layer of the atmosphere is composed of ionized gases this layer is called the ionosphere the high frequency waves penetrate into the ionosphere and into space therefore communication satellites are used to reflect these waves back to earth which are then captured by the receiving [Music] antennas microwaves can penetrate the atmosphere of the earth this is the reason why they are used for satellite communications microwave signals are transmitted by an antenna to a satellite which amplifies and retransmits the signal to an antenna in another part of the world this is how we communicate with the rest of the world most communication satellites are used to send and receive radio signals for telephone services while the rest are for television broadcasting scientific research and weather forecast microwaves have short wavelengths and are reflected by small objects this property is used in radars radar is an acronym for radio detection and ranging a radar system consists of an antenna transmitter and a receiver the antenna whirls around continuously to scan the surrounding area the transmitter sends out a narrow beam of microwaves in short pulses a distant object reflects some of the signal back to the receiver the direction to which the signal was received gives the direction of the object the distance of the object can be calculated from the time lag between the transmitted pulse and the reflected pulse have you noticed that a lot of people now resort to cable tv for news entertainment and educational programs cable tv is now used because of its wide range of channels and clearer sound and picture moreover some cable companies provide internet access to users so how does cable tv work 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 are broadcasted and watched lived around the world a cell phone is a radio transmitter and receiver that uses microwaves a cellular phone is a very sophisticated radio but still a radio nonetheless it is today's answer to the emerging demand for mobile communication cellular phones depend on overlapping network of cells or areas of land several kilometers in diameter each cell has its tower that receives and sends microwave signals in a microwave oven food absorbs certain microwave frequencies very strongly the microwaves penetrate the food being heated it will agitate the water molecules within the food thus creating molecular friction which then produces heat that will cook it infrared waves are in the lower middle range of frequencies in the electromagnetic spectrum infrared radiation lies beyond the red end of the visible light the size of infrared waves ranges from a few millimeters down to microscopic lengths the longer wavelength infrared waves produce heat and include radiation emitted by fire the sun and other heat producing objects shorter wavelength infrared rays do not produce much heat and are used in remote controls and imaging technologies the amount and wavelength of radiation depend on temperature below 500 degrees celsius an object emits only infrared radiation above 500 degrees celsius an object glows and emits both infrared and visible light the difference in color determine the differences in temperature for example shades of blue and green indicate regions of colder temperature and red and yellow indicate warmer temperature [Music] the human eye is not sensitive to the infrared light used by television remote controls to send a signal to a television remote controls often use a diode that emits light some digital cameras have filters to block near infrared light but most can detect it it shows up on the screen as if it were visible light when you press a button on the remote control the camera may show a pulsing light emitted by the remote the following are some useful applications of infrared radiation infrared photographs taken from a satellite with special films provide useful details of the vegetation in the earth's surface infrared scanners are used to show the temperature variation of the body this can be used for medical diagnosis infrared remote controls are used in tvs and other electronic appliances an infrared camera has a transmitter that sends out infrared pulses and lastly night vision goggles allow images to be produced in levels of light approaching total darkness when white light passes through a prism it is separated into its constituent colors red orange yellow green blue indigo and violet these colors do not distinctly separate but they continuously change from red to violet red has the longest wavelength from among these colors and violet has the shortest our eyes are sensitive to electromagnetic waves of wavelengths that range from 4 times 10 raised to negative 7 power meters to 7 times 10 raised to negative 7 power meters these are the range of wavelengths of white light thus the spectrum of white light is therefore called the visible spectrum visible light is essential for photosynthesis photosynthesis is the process by which plants make food forms of energy taken from the sun used by plants and microorganisms millions of years ago are locked up in coal and oil used as energy resources today there are several ways in which a luminous object can be made to give off energy in the form of light a luminous object can produce incandescent light fluorescent light and neon light incandescent light is a form of light produced by heat they produce light when electricity is applied to them inside the glass bulb is a thin wire filament made of metal tungsten tungsten can be heated to over 2000 degrees celsius without melting fluorescent light is cooler and uses less energy than incandescent light instead of being used to build up heat electrons in fluorescent lights are used to bombard molecules of gas kept at low pressure in a tube the collar that a fluorescent bulb produces depends on the phosphorus used neon light can be seen in thin glass tubes of brightly colored lights it is a cool light similar to fluorescent light when electrons pass through the glass tubes filled with certain gases light is produced the most common type of gas used is neon gas which produces bright red light if other gases are added however different colors are produced ultraviolet radiation lies just beyond the violet end of the visible spectrum ultraviolet waves have shorter wavelengths than the visible light and carry more energy the sun is our main source of ultraviolet gradation but there are also artificial sources of uv light ultraviolet radiation in uv lamps are used by banks to check the signature on a passbook the signature is marked on the passbook with fluorescent ink it becomes visible when viewed under a uv lamp these lamps are also used to identify fake banknotes uv radiation is also used in sterilizing water from drinking fountains some laundry detergents also contain fluorescent chemicals which glow in sunlight this makes your shirt look whiter in daylight [Music] uv radiation in sunlight helps reduce vitamin d in the skin and gives us a tanning effect x-rays come just after the ultraviolet rays they are of shorter wavelengths but carry higher energy than ultraviolet rays x-rays are produced using an x-ray too they are emitted when fast-moving electrons hit the metal target x-rays were discovered by willem conrad renkin in 1895. long wavelength x-rays can penetrate the flesh but not the bones they are used in x-ray photography to help doctors look inside body they are useful in diagnosing bone fractures and tumors wavelength x-rays can penetrate even through metals they are used in industry to inspect welded joints for faults gamma rays lie at the other end of the electromagnetic spectrum they are shortest in wavelength and highest in frequency gamma rays are emitted by only the most energetic cosmic objects such as pulsars neutron stars supernovas and black holes terrestrial sources include lightning nuclear explosions and radioactive decay gamma ray wavelengths are measured on the subatomic level and can actually pass through the empty space within an atom gamma rays can destroy living things fortunately the earth's atmosphere absorbs any gamma rays that reach the planet gamma rays carry the highest amount of energy thus they are more dangerous they can also be blocked with lead and thick concrete gamma rays are very strong that they can kill living cells gamma rays are used to treat cancer through the process called radiotherapy they are also used for sterilization of drinking water now let's wrap things up here's a table to summarize the applications and uses of each electromagnetic wave radio waves are used in radio and television communication microwaves are used in satellite communication terrestrial communications radar and microwave ovens infrared rays are found in remote controls infrared scanners night vision goggles camera autofocus and thermograms visible light is important in photosynthesis in plants it can be used as artificial lighting optical fibers in medical uses and screens of electronic devices ultraviolet rays are used to sterilize water from drinking fountains and checks signatures on a passbook it's also used to identify fake banknotes x-rays are used in the field of medicine and engineering lastly gamma rays are also used in the medical and industrial fields that's all for now we will be discussing about the effects of electromagnetic radiation on living things in the environment in our next video so stay tuned see you on our next video and don't forget to keep your minds busy if you like this video please subscribe to our channel and hit the notification icon for more videos like this