Destructive Interference and Light?

[RyanJ]

Hi there everyone!

 

I have a new question. In physics yesterday we learned about how two sound waven in anti-phase and cancel each other out causing there to be no sound as a result.

 

To my question can this occur with light? If for example you could have a light source emitting [acr=Electromagnetic]EM[/acr] light waves then could you in theory find a point where these waves are deconstructivley interfered with resulting in no light?

 

Cheers,

 

Ryan Jones

[BigMoosie]

Yes you can! This article might be of interest: http://en.wikipedia.org/wiki/Double-slit_experiment

[RyanJ]

Yes you can! This article might be of interest: [url']http://en.wikipedia.org/wiki/Double-slit_experiment[/url]

 

Looks interesting - I'll try that in school on monday

 

Cheers,

 

Ryan Jones

[swansont]

You can do it with electrons, neutrons and atoms, too.

[RyanJ]

You can do it with electrons, neutrons and atoms, too.

 

You can do ti with any particel too then? Is that to do with the particle-wave duality?

 

Cheers,

 

Ryan Jones

[Klaynos]

You can do ti with any particel too then? Is that to do with the particle-wave duality?

 

Cheers' date='

 

Ryan Jones[/quote']

 

 

Yes it is to do with wave-particle duality, it is actually one of the pieces of evidence normally sighted for the wave nature of electrons.

 

I belive the largest thing it has been done with is c60 a "buckyball"...

[RyanJ]

Yes it is to do with wave-particle duality' date=' it is actually one of the pieces of evidence normally sighted for the wave nature of electrons.

 

I belive the largest thing it has been done with is c60 a "buckyball"...[/quote']

 

I knew sub atomic particles could have this done thanks to a book I read called "The Fabric Of the Cosmos" but I had no idea you could do it with things that are bigger than subatomic particles let along something as large as buckyball!

 

Cheers,

 

Ryan Jones

[BhavinB]

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

 

The dark zones in the resulting image are where light destructively interferes.

There are a few famous interferometers. I'd say the most widely known is the Fabry-Perot interferometer, just cuz the concept is useful for lasers, filters etc...

 

B

[swansont]

atom interferometers (which were the application of my thesis project, which was building a slow atom source for such a device.)

 

molecular interferometry and buckeyball interference

[RyanJ]

BhavinB, swansont: Thanks for the links - I will have a look at those.

 

Then it is true - you do learn something new every day

 

Cheers,

 

Ryan Jones

[srystiq]

This phenomenon is quite cool to see with sound as well, if you have two old speakers and you position them apart as you walk across the front you will realise there are places where the sound is quieter. Im fairly sure it works.

[BigMoosie]

I opened up a sound file and duplicated the left speaker, inverted it and put it through the right, then when I moved the two speakers together you could hear an immediate onvious drop in the volume, later if I have some time I might upload a sound file like this for others to try, its great.

[danny8522003]

We did this experiment in physics too, with both electrons, lasers and sound. They're all pretty fascinating, but the QM explanation is a bit of a head scratcher.

 

Even if you fire one photon at a time at the slits (called Young's Slits), they still build up the same interference pattern as if the photon goes through BOTH the slits and interferes with itself. QM says that the photon/electron etc traverse ALL available paths through the slits at once and end up somewhere through probability to build the pattern.

 

Your physics teacher may also start talking about phasors which explains this.