previous    next
λ1=50 pt and λ2=60 pt




In the above example we have chosen λ1=50 pt and λ2=60 pt (our length unit is here 1 point (pt) which is comparable to pixel).
The speed of waves in the medium equals v=100 pt/s.
We may determine the wavenumbers for the two waves

k1 = 2π/λ1 = 0.126 pt-1      and      k2 = 2π/λ2 = 0.105 pt-1

and, furthermore the angular frequencies

ω1 = vk1 = 12.6 Hz      and      ω2 = vk2 = 10.5 Hz

We obtain then
ω = (ω1 + ω2)/2 = 11.5 Hz

     and     

Δω/2 = (ω1 - ω2)/2 = 1.0 Hz

and, moreover,

k = ω/v = 0.115 pt-1      and      Δk/2 = Δω/2v = 0.010 pt-1






next