Ultrasounds

• What happens when ultrasound reaches a boundary between two media?

  They are partially reflected back
• What frequency is ultrasound?

  Above 20,000Hz
• Why do bats naturally produce ultrasound for?

  • Echolocation
  • Communication
• Is ultrasound safe?

  Yes
• How is time taken for the ultrasound to bounce back useful?

  It can be used to calculate the thickness of the medium
• How is ultrasound used by boats and subs?

  By reflecting the ultrasound off the sea floor, we can calculate the distance from the sea floor
• What is infrasound?

  The opposite of ultrasound - it is a sound wave with a frequency less than 20Hz