Clashing Electromagnetic Waves

[jamest]

No hidden agenda here. I'm just wondering how/why different frequencies of electromagnetic waves don't interfere with each other, like waves in a pond. I was driving earlier today, and it occured to me that the specific frequency of radio signal I was hearing was clear and precise... and I just wondered how that could be when the space around me was rich in the diversity of specifc radio frequencies. Why don't they interfere with each other?

[Pappa]

No hidden agenda here. I'm just wondering how/why different frequencies of electromagnetic waves don't interfere with each other, like waves in a pond. I was driving earlier today, and it occured to me that the specific frequency of radio signal I was hearing was clear and precise... and I just wondered how that could be when the space around me was rich in the diversity of specifc radio frequencies. Why don't they interfere with each other?

I think waves in a pond pass right through each other too.

[jamest]

No hidden agenda here. I'm just wondering how/why different frequencies of electromagnetic waves don't interfere with each other, like waves in a pond. I was driving earlier today, and it occured to me that the specific frequency of radio signal I was hearing was clear and precise... and I just wondered how that could be when the space around me was rich in the diversity of specifc radio frequencies. Why don't they interfere with each other?

I think waves in a pond pass right through each other too.

Water waves interfere with one another, don't they? If not, then what are 'interference patterns'?

[Pappa]

No hidden agenda here. I'm just wondering how/why different frequencies of electromagnetic waves don't interfere with each other, like waves in a pond. I was driving earlier today, and it occured to me that the specific frequency of radio signal I was hearing was clear and precise... and I just wondered how that could be when the space around me was rich in the diversity of specifc radio frequencies. Why don't they interfere with each other?

I think waves in a pond pass right through each other too.

Water waves interfere with one another, don't they? If not, then what are 'interference patterns'?

Well both are true. Individual waves interfere with each other and are increased or decreased by the interaction of multiple waves, but the energy doesn't disappear and they pass through each other too. Sorry, my answer wasn't really relevant to your question.

[ficklefiend]

These are the times I wish I understood physics better.

Although definitely radio waves are subject to interference... can you make head or tail of this wiki article?

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

I'm trying.



I don't even understand how they always travel at the same speed, surely the electromagnetic fields are not constant through space? Why is the speed constant then? Argh.

[Feck]

These are the times I wish I understood physics better.

Although definitely radio waves are subject to interference... can you make head or tail of this wiki article?

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

I'm trying.



I don't even understand how they always travel at the same speed, surely the electromagnetic fields are not constant through space? Why is the speed constant then? Argh.

waves move at different speeds according to the medium they are in .

[jamest]

These are the times I wish I understood physics better.

Although definitely radio waves are subject to interference... can you make head or tail of this wiki article?

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

I'm trying.



I don't even understand how they always travel at the same speed, surely the electromagnetic fields are not constant through space? Why is the speed constant then? Argh.

Erm, just looking for layman explanations here, if possible.

[jamest]

waves move at different speeds according to the medium they are in .

Presumably, the diversity of the radio waves in the space above my head, earlier today, were all travelling through the same medium. And I thought that the speed of electromagnetic waves was a constant, through any specific medium?

[ficklefiend]

Ok, so we seem to have gotten this far - EM waves do interact, but in simple terms their pattern is not destroyed by other waves, their pattern is combined.

Next- how do they uncombine? Why can my radio still pick up two (or rather many) separate wave frequencies?

[Pappa]

Ok, so we seem to have gotten this far - EM waves do interact, but in simple terms their pattern is not destroyed by other waves, their pattern is combined.

Next- how do they uncombine? Why can my radio still pick up two (or rather many) separate wave frequencies?

It only 'listens' for one frequency at a time though.

And they uncombine because they never actually combine in the first place. Imagine two waves on a pond, they never actually combine as one, they just pass through each other... but if their peaks and troughs occur in the same place, they become the sum of both.

[Feck]

waves move at different speeds according to the medium they are in .

Presumably, the diversity of the radio waves in the space above my head, earlier today, were all travelling through the same medium. And I thought that the speed of electromagnetic waves was a constant, through any specific medium?

Yes and em waves of similar frequencies do interfere with each other .

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

[ficklefiend]

Ok, so we seem to have gotten this far - EM waves do interact, but in simple terms their pattern is not destroyed by other waves, their pattern is combined.

Next- how do they uncombine? Why can my radio still pick up two (or rather many) separate wave frequencies?

It only 'listens' for one frequency at a time though.

And they uncombine because they never actually combine in the first place. Imagine two waves on a pond, they never actually combine as one, they just pass through each other... but if their peaks and troughs occur in the same place, they become the sum of both.

So it is to do with their direction?

Of course, you couldn't send two waves in exactly the same direction at exactly the same time, could you? So that never happens and they are always just passing through each other.

[Pappa]

Ok, so we seem to have gotten this far - EM waves do interact, but in simple terms their pattern is not destroyed by other waves, their pattern is combined.

Next- how do they uncombine? Why can my radio still pick up two (or rather many) separate wave frequencies?

It only 'listens' for one frequency at a time though.

And they uncombine because they never actually combine in the first place. Imagine two waves on a pond, they never actually combine as one, they just pass through each other... but if their peaks and troughs occur in the same place, they become the sum of both.

So it is to do with their direction?

Of course, you couldn't send two waves in exactly the same direction at exactly the same time, could you? So that never happens and they are always just passing through each other.

Not the direction. Wave "interference" gives the wrong impression of what goes on really. Waves just do their own thing, but if their peaks and troughs ever happen to coincide, they add amplitudes. So a 5cm peak plus a 5cm peak becomes a 10cm peak, same with troughs. They may only coincide in a short area, after that they just go on their way.... or they may coincide again and again and again... then they keep adding amplitudes, like a sonic boom.

[jamest]

It only 'listens' for one frequency at a time though.

When waves in a pond interfere with one another, their original attributes/characteristics dissolve into another combined pattern. So, if those original attributes are destroyed by the combination event, then what remains of the original wave to 'listen' to?
I'm wondering why, for instance, the original radio waves that leave the BBC aren't lost in the interferences that they encounter before they enter my radio.

And they uncombine because they never actually combine in the first place. Imagine two waves on a pond, they never actually combine as one, they just pass through each other... but if their peaks and troughs occur in the same place, they become the sum of both.

I don't see how two material forces can pass through each other without affecting one another.

[Pappa]

It only 'listens' for one frequency at a time though.

When waves in a pond interfere with one another, their original attributes/characteristics dissolve into another combined pattern. So, if those original attributes are destroyed by the combination event, then what remains of the original wave to 'listen' to?
I'm wondering why, for instance, the original radio waves that leave the BBC aren't lost in the interferences that they encounter before they enter my radio.

And they uncombine because they never actually combine in the first place. Imagine two waves on a pond, they never actually combine as one, they just pass through each other... but if their peaks and troughs occur in the same place, they become the sum of both.

I don't see how two material forces can pass through each other without affecting one another.

The original attributes are not destroyed at all. They are maintained fully.

I don't know the underlying physics well enough to explain it better than simply saying... picture a pond with two stones dropped in a few meters apart and see what the waves do. They simply pass through each other. They meet and interfere where the peaks and troughs occur together, but then they just carry on as if neither was there.

After all what is a wave? It's just a manifestation of some energy travelling through matter. Look at it the other way round and wonder why should they affect one another anyway?