Refraction

• Refraction is when the velocity (and sometimes wavelength) of the absorbed wave is affected by the properties of the new medium. As the wave crosses the boundary it travels in a different direction.
• The speed of sound whilst travelling through a medium depends on elasticity and density
• Elasticity: the measure of a medium's tendency to return to its original shape after being bent, stretched or compressed.

  • waves travel faster in more elastic mediums, as solids are more elastic than liquids, state changes effect speed of travel
• Density

  • the denser the medium, the slower the wave travels
  • because: a greater mass per unit is more difficult for a given force to move through
• Young's Modulus (E): a measure of a mediums stiffness/elasticity

  Measured in N m^-2
• As temperature increases (decreased density) the speed of travel increases

  ->therefore refraction can occur on a temperature boundary