Waves 2

Waves 2

1. Principle of superposition

   • When 2 waves travelling in the opposite direction meet, the total displacement at a point is equal to the sum of the individual displacements at that point.
   • when a crest meets a crest it forms a supercrest
   • when a trough meets a trough it forms a supertrough
   • when a crest meets a trough the resultant displacement is 0

2. Stationary waves

   • all particles vibrate at same frequency except at nodes
   • amplitude varies from 0 at nodes to maximum at antinodes
   • distance between adjacent nodes = 1/2 λ
   • Examples = sound in a pipe, microwaves plucking a guitar string

3. Progressive waves

   • all particles vibrate at same frequency
   • amplitude is same for all particles
   • phase difference is equal to 2πd/λ

4. Equations

   • C = fλ
   • period = 1/f
   • frequency = 1/T