Waves

Waves

1. Superposition and Coherence

   • Superposition occurs when two or more waves pass through each other.
     • At the instant the waves cross, the displacements due to each wave combine.
   • The principle of superposition says that when two or more waves cross, the resultant displacement = the vector sum of the individual displacements.
   • Constructive interference
     • Crest + crest = big crest
     • Trough + trough = big trough
   • Destructive interference
     • Crest + trough of equal size = nothing = total destructive interference
   • Phasors
     • Used to show superposition
       • The arrows represent the phase of each point on a wave.
         • The phasor rotates anticlockwise through one whole turn as the wave completes a full cycle.