ultrasound

• ultrasound is sound with frequencies higher than 20000 Hz
• when a wave passes from one medium into another some of the wave is reflected off the boundary between the two media and some is transmitted and refracted. this is partial reflection
• pointing a pulse of ultrasound at an object, some of the ultrasound get reflected back from the boundary. the time it takes for the reflections to reach a detector can be used to measure how far away the boundary is
• ultrasound can pass through the body, when they reach a boundary some of the wave is reflected back. the timing and distribution of these echo's are processed by a computer to produce image of foetus
• ultrasound can also be used to find flaws in pipes or materials such as wood or metal. when entering a material, ultrasound waves will be reflected by the far side of the material. if there is a flare, the wave will be reflected sooner
• echo sounding uses high frequency sound waves, used by boats and submarines to find out the depth of water they are in or to locate objects