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waves - Coggle Diagram
waves
echoes
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audible sound ranges in frequency from 20 Hz to 20 000 Hz. sound above 20 000 Hz is called ultrasound can be detected by bats dogs dolphins and many other animals
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radar
stands for radio detection and ranging and was originally developed during world war II to detect enemy aircraft
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used by air traffic controllers to track passengers airliners, by the military to track missiles and by coast guards to detect ships.
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electromagnetic waves
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ultra violet 10 nm : certain wavelengths can damage skin cells, disrupting skin dna and leading to skin cancer
microwaves 2 cm : cause internal heating of body tissues which, some say, can lead to eye cataracts
gamma 0.01 nm : damage cells and disrupt dna, which may lead to cancer
x-rays 0.1 nm : damage cells and disrupt dna, which may lead to cancer
radio waves 1000 m : large doses of radio waves are believed to cause cancer, leukaemia and other disorders and some people claim the very low frequency radio waves from overhead power cables near their homes has affected their health
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scanning metal castings
railway tracks do not last forever. they wear out. so it is important that we find out early if they are developing cracks or flaws below the surface.
we can do this with ultrasound scanners attached to specially fitted tail carriages. ultrasound passes through the track. if there is a crack or other flaw it can be imaged (using the same science that allows us to obtain a picture of ab baby in the womb)
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transverse waves
is one in which the particles vibrate perpendicular to the direction in which the wave is travelling
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sonar
sound navigation and ranging and was originally developed to detect submarines in the early twientieth century, however, the following example illustrates its use by fishermen to detect shoals of fish and to measure how far they are below the surface
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