Doppler Effect

• Doppler effect occurs when there is a relative movement between the wave's source and the observer, affecting the apparent frequency and not the actual frequency itself.

  
  

  Proposed by Christian Doppler in 1842
• HOW IT WORKS - NO EFFECT

  If the wave source is stationary compared to the observer, the waves will be received at the same rate they are being created, therefore showing no apparent change in frequency
• HOW IT WORKS - WITH EFFECT

  If the wave source is travelling towards the observer, each wave is created closer than the previous and therefore traveling a smaller distance, thus shortening the distance between wavefronts.

  -> the frequency at arrival is higher

  If moving away, frequency has an apparent lower pitch