Behaviour of waves

Behaviour of waves

1. Standing waves

   • Progressive waves - the wave is propagating such that the position of the peaks and troughs are moving and energy is being transferred
     • Standing waves - the wave position of the peaks and troughs are stationary.
       • Created when a progressive wave is reflected at a fixed boundary such that a coherent but inverted reflected wave is created with a phase difference of 180 degrees. The two waves are then superposed, creating points of maximum displacement (antinodes) due to constructive interference and points of zero displacement (nodes) due to destructive interference as they move past one another
         • Only occurs when hard reflection occurs.
       • At the fundamental frequency, wavelength = 2l
         • For any standing wave, wavelength = 2l / n where n is a whole number (which coincides with the harmonic)
           • 2nd harmonic - wavelength = 2l / 2
           • Amplitude and wavelength decrease as harmonic number increases
           • speed of wave = square root(Tension / mass per unit length)
             • f =( n / 2l) x square root(Tension / mass per unit length)

2. Refraction

3. Reflection

   • angle of incidence = angle of reflection

4. Diffraction

5. Intererference

   • Principle of superposition - when two or more waves meet, the total displacement at any point is the sum of the displacements that each individual wave would cause at that point

6. Path difference

7. Polarisation