Why Does Diffraction Occur Even When Wavelength Exceeds Aperture Width?

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Ok thanks for the link, but anyone have an answer(s) to my last questions(in the same post)?
 
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Please? I think this is my last question.
 
Byrgg said:
Wow! Seriously? Is that all really correct? You're not joking?
No, I'm not joking :biggrin:
Byrgg said:
One more question, in multiple-slit diffraction, do the waves from one slit ever diffract into another one of the other slits?
Byrgg said:
but anyone have an answer(s) to my last questions(in the same post)??
Byrgg said:
Anyone? Please?
Byrgg said:
Please? I think this is my last question.
Patients if a virtue my friend, remember some of us are on different time zones :-p. No, as said previously, with any appature (including double slit), the maximum angle of diffraction is 90o, so when the wavefront reaches the other slit it is traveling perpendicular to the slit, so no diffraction will occur at that point and the waves are not diffracted back into the slit. However, the waves do interfere in the area between the slits and between the slits and the screen.
 
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Ok, sorry about that, wasn't thinking of time zones. Is there any reason why it doesn't diffract through the other holes? Or does this not occur because the waves destructively interfere between gaps(do they destructively interfere there?). Even if there were multiple gaps, and only one had waves coming from it, it still wouldn't go through the other holes?
 
Byrgg said:
Ok, sorry about that, wasn't thinking of time zones. Is there any reason why it doesn't diffract through the other holes? Or does this not occur because the waves destructively interfere between gaps(do they destructively interfere there?). Even if there were multiple gaps, and only one had waves coming from it, it still wouldn't go through the other holes?
Take a look at http://micro.magnet.fsu.edu/primer/java/interference/doubleslit/doubleslitjavafigure1.jpg" , now the diffracted waves will br traveling either parallel to the slits or away from them. The waves do not diffract into the slits simply because there is nothing to diffracted through or around. Does that make sense?
 
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Yeah, I think I get it now. They only diffract if they're going towards the gap or perpendicular right? Parallel wouldn't really do it I don't think... but then how exactly does diffraction around a corner work then? Say the waves were traveling along a barrier and came to a corner, that could be seen as a gap sort of couldn't it?, and don't the waves bend around corners?

Say a wave is moving forward, if it comes to a corner, then it continues forward, while diffracting around the corner as well right? The forward gap is perpendicular to the wave's direction, while the right/left gap is parallel. Is this explanation ok or should I try to make a diagram?
 
Byrgg said:
Yeah, I think I get it now. They only diffract if they're going towards the gap or perpendicular right? Parallel wouldn't really do it I don't think... but then how exactly does diffraction around a corner work then? Say the waves were traveling along a barrier and came to a corner, that could be seen as a gap sort of couldn't it?, and don't the waves bend around corners?

Say a wave is moving forward, if it comes to a corner, then it continues forward, while diffracting around the corner as well right? The forward gap is perpendicular to the wave's direction, while the right/left gap is parallel. Is this explanation ok or should I try to make a diagram?
When sound gets diffracted around a corner, a component of the wave will be traveling towards the slit, because the waves are radiating from a point source, they are not traveling completely perpendicular to the slit. http://hyperphysics.phy-astr.gsu.edu/hbase/sound/imgsou/difr2.gif" Whereas in the double slit case, the source is in line with the slit and so the waves are either traveling away from the slit or perpendicular to it. Does that make sense?
 
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Oh I think I see now, you said at a corner it still goes because it's partially going towards the slit right? You also mentioned that it's from a point source, that basically means it's radiating out and this is why it's partially aimed towards the slit right? If the point source was right in the wall(in theory) then would the waves still go around the corner?
 
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Byrgg said:
Oh I think I see now, you said at a corner it still goes because it's partially going towards the slit right? You also mentioned that it's from a point source, that basically means it's radiating out and this is why it's partially aimed towards the slit right? If the point source was right in the wall(in theory) then would the waves still go around the corner?
Yeah that's it.
 
Actually what I meant is if the source is right in the wall then isn't it sort of like already being diffracted through a single slit? The waves would be parallel(wavelength perpendicular) to the left/right slit. In this case the waves shouldn't pass through should they?
 

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