Ultrasound

• when do ultrasounds partially reflect

  when they reach a boundary between two media - the remainder of the waves continue and pass throughf
• how are ultrasounds used to see things

  waves will reflect earlier or later depending when they hit the object
• infrared and ultrasound


  infrasound is the opposite of ultrasound

  they are sound waves with a frequency lower than 20Hz - known as seismic waves
• features of P waves

  longitudinal, can pass through solids and liquids
• features of S waves


  transverse, can only pass through solids, move slower
• why can we guess the core of the Earth is liquid

  on the opposite side of the Earth to an Earthquake, only P waves are detected - the core is liquid, no S waves can penetrate it
• how is sonar used to calculate the depth of water

  pulse of ultrasound is send below a ship, the time taken for it to reflect and reach the ship can be used to calculate depth

  used to work out if theres fish below the ship

  or how far the seabed is