ultrasound

• what happens when a wave passes from one medium to another?

  some of the wave is reflected off the boundary between the 2 media and some is transmitted (and refracted). This is partial reflection.
• can ultrasound waves pass through the body?

  yes
• what are the 2 uses of ultrasound?

  • medical imaging
  • industrial imaging
• what is an example of how ultrasound is used in medical imaging?

  pre-natal scanning of a foetus.
• what is an example of how ultrasound is used in industrial imaging?


  finding flaws in materials.
• what is are the examples of 2 media that a wave will reach at a boundary?

  fluid in the womb and the skin of the foetus.
• what is processed by a computer to produce a video image of the foetus?

  the exact timing and distribution of the echoes (reflected waves).
• is ultrasound imaging safe?

  yes
• in what materials can ultrasound find flaws in?

  • pipes
  • wood
  • metal
• what will usually happen to ultrasound waves entering a material?

  they will be reflected by the far side of the material. If there is a flaw such as a crack inside the object, the waves will be reflected sooner.
• what is echo sounding?

  a type of sonar used by boats and submarines to find out the distance to the seabed or to locate objects in deep water.
• the time it takes for the reflectio of a wave at a boundary can be used to measure what?

  how far away the boundary is.
• ultrasound is sound with frequencies higher than what?

  20000 Hz
• electrical devices can be made that produce electrical oscillations of any frequency, what can these easily be converted into?

  mechanical vibrations to produce sound waves above 20000 Hz.