Why does slit diffraction occur?

[CrimpJiggler]

Is it the same thing as Bragg diffraction, in the sense that it is caused by the photons being scattered in different directions when it hits the atoms of the solid material around the slit?

 

[adjacent]

http://en.wikipedia.org/wiki/Diffraction

 

[dauto]

No, slit diffraction is independent of the properties of the material on which the slits are built (As long as the material blocks the radiation from passing right through it.). Slit diffraction happens as a consequence of scattering due to Huygens principle which states that any point in a wave can be taken as a point source for new waves.

 

[CrimpJiggler]

Ah yeah I was thinking of x-rays which are scattered by electron clouds. Huygens principle, thanks.

 

[CrimpJiggler]

A side question: When two electromagnetic waves interfere, is the change in amplitude permanent, meaning will they still have altered amplitudes even when they are no longer near each other?

 

[jtbell]

No, after the two waves "separate", they continue as if they had never encountered each other.