Ultra sound

Ultra sound

1. Have a frequency of more than 1MHz, whereas the human's range is 20 kHz

   • They are above the human hearing range and therefore we can't hear them
     • They can be produced from some electronic devices and by animals such as bats and dolphins

2. Reflections

   • when ultrasound reaches a boundary between to medias of different densities they are reflected. They remainder continues to travel through
   • Detectors can be used to measure the times between the waves reflections and calculate a distance using the formula distance= speed x time

3. Medical uses

   • The human body is composed of different tissues which when ultrasound is passed through can be detected, when it reaches boundaries
   • These waves can be used in pre-natal scanning to check to see whether the foetus is growing normally. Computers combine the ultrasound detections to produce an image
   • Ultrasound can also be used for diagnostics. Such as organs like the liver.
   • Used to remove kidney stones
     • Crystal which form from compounds found in urine, they can cause blockages in the ureter.
     • The high frequency ultrasound waves can be directed at the stone and cause it to vibrate which make sit break down into smaller pieces and be passed in the urine

4. Comparing ultrasounds and x-rays

   • X-rays have a shorter wave length and higher frequency, meaning that x-rays produce higher quality images
     • Showing greater clarity and detail, which can be vital to determines fractures etc
       • CT scans produce even clearer image (still use x-rays) and produce a 3D image allowing them to look at the different layers at different angles, without objects overshadowing the image (like with an x-ray)
   • X-rays are ionising which means they can damage living tissue, ultrasounds are better for human health
     • Dividing cells can be most vulnerbable to the radiation
     • Ultrasound is not ionising so it is much safer when perforimng pre-natal scans

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