Ultrasound

• Ultrasound


  Sound with Frequencies Higher Than 20 000 Hz
• Producing ultrasound


  1. Electrical devices can produce electrical oscillations

  2. Electrical oscillations can be converted into mechanical vibrations to produce sound waves beyond the range of human hearing
• Ultrasound pops up all over the place
• Ultrasound waves


  • They get partially reflected at boundaries between media
• Partial reflection of ultrasound waves

  1. Wave passes from one medium into another

  2. Some of the wave is reflected off the boundary

  3. Some of the wave is transmitted and refracted
• Pointing a pulse of ultrasound at an object

  Wherever there are boundaries between one substance and another, some of the ultrasound gets reflected back
• Measuring distance using ultrasound

  The time it takes for the reflections to reach a detector can be used to measure how far away the boundary is
• Medical and industrial uses of ultrasound

  • Ultrasound waves can pass through the body
  • Reflections are detected and processed to produce video images
  • Ultrasound can be used to find flaws in objects
• Using ultrasound to detect flaws

  1. Ultrasound waves entering a material are usually reflected by the far side

  2. If there is a flaw such as a crack inside the object, the wave will be reflected sooner