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Waves - Coggle Diagram
Waves
Hearing
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The vibrations are passed on to tiny bones in the ear called ossicles, throught the simicircular canals and to the cochlea
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Humans can only hear sounds between 20Hz and 20,000 Hz
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Waves at boundaries
Whenever a wave reaches the boundary between two materials, the wave can be: reflected, refracted, transmitted or absorbed
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Waves are transmitted when they pass through a body, radio waves passing through walls.
Waves are absorbed when they are taken in by a body and don't pass through it, like microwaves absorbed by food
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Seismic waves
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P - waves, longitudinal and can travel through solids and liquids
S - waves, transerse and can only travel through solids, can't pass through liquids
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Exploring the earth
Seismic waves can be detected at different points on the surface, using detectors called seismometers
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Data can be used to uderstand the structure of the earth since we know that P waves can travel through liquid and solids while s waves can't travel through liquids
When the medium the waves are travelling through suddenly changes, the direction changes, and the path has a kink
By measuring the seismic waves detected at various points, the paths the waves have travelled along can be created, and the different boundaries between materials can be figured out
Wave Basics
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Longitudinal waves
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contain compressions and rarefractions, when the wave spreads out and gets closer
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Ultrasound
Sound waves with a frequency greater than 20,000 Hz
Properties
When waves pass from one medium to another, some are reflected and some are transmitted. This is called partial reflection
If you point a pulse of ultrasound at an object, some of it will be reflectd back
When sound waves are reflected by surfaces, there is a delay between you hearing the original sound and the reflected sound
Reflected waves have to travel further, taking longer to reach our ears. This is known as an echo
The time it takes for the relfections to reach a detector can be used to measure how far away a boundary is
Uses
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Industrial imaging
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If there is a crack, the waves will be reflected from it, and be detected sooner
Echo sounding
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When calculating the distance, divide by 2 because the wave has travelled to the sea bed and back