Diffraction

[fredrick]

Im getting confused with the amount of diffraction of sound and of light.

For light Means diffraction occurs, how about if that ratio was above 1 or below 1, how significant is the diffraction relative to when the ratio =1. And is it the same for diffraction of sound?

[dcc]

For electromagnetic radiation:

, where is the amount of diffraction.  For significant diffraction to occur, should be true.  As decreases, the amount of diffraction gradually decreases.

This was emphasised in last years assessment report (http://www.vcaa.vic.edu.au/vce/studies/physics/assessreports/2007/physics2_assessrep_07.pdf), which stated:

Some areas of concern from this exam included:

• the distinction between diffraction as it applies in ‘Interactions of light and matter’ compared with ‘Sound’
• the gradual change in diffraction patterns as the λ/w ratio is varied

Sound (I believe) is very much the same, however the focus of the Sound unit is slightly different to Light & Matter, so it depends upon the question I suppose.  (i.e. for single slit diffraction, the distance between 'bright' regions increases as diffraction increases, whereas a sound wave diffracting allows sound to be heard around 'corners' lol)