yorobun
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"Stationary waves are so called as profile of the wave does not move along, it only oscillates. This also means that wave energy does not pass along a standing wave;as such they do not meet our strict definition o waves, which do transfer energy and are more precisely called progressive waves"

Please could anyone explain the difference between progressive wave and a stationary wave. I copied a paragraph from my textbook and it doesn't make sense and we haven't even covered 'progressive wave' in lessons.
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derpz
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(Original post by yorobun)
"Stationary waves are so called as profile of the wave does not move along, it only oscillates. This also means that wave energy does not pass along a standing wave;as such they do not meet our strict definition o waves, which do transfer energy and are more precisely called progressive waves"

Please could anyone explain the difference between progressive wave and a stationary wave. I copied a paragraph from my textbook and it doesn't make sense and we haven't even covered 'progressive wave' in lessons.
Progressive waves are longitudinal or transverse waves which basically transfer energy from one point to another. For example any wave out of the electromagnetic spectrum is progressive (e.g. visible light transfers energy in the form of light).

Standing waves on the otherhand trap energy between two points. You also need to know how they are formed:

Progressive waves are initially formed, which would travel in opposite directions, and then be reflected off whatever is keeping the medium together and when they reflect back, they interfere and form "nodes" and "antinodes".

This might make it easier to understand:


Here, the vibrator would have a certain frequency, which would first form a progressvie wave. This wave would then be reflected off the pulley and the vibrator as it travels along the string. It then interferes constructively and destructively.

This is where "nodes" and "antinodes" come in.

Constructive interference = Antinode forms
Destructive interference = Node forms

A node is the minimum aplitude on a standing wave. Here, it would be the points where it seems like the string interceps, as the amplitude is zero.

An antinode is where the amplitude is maximum, which is the centre of the oval like shape formed, from the bottom to the very top.

If that doesnt really make sense, this should:


Also, a key difference is to remember that a standing wave has many amplitudes, whereas a progressive wave has only 1 amplitude which would be the max point. For example, on the standing wave any point between a node and antidnode is an amplitude but on a progressive wave these would just be points on the wave which have displacements.

Here's a comparison between the two:

I know my explanation is kind of hard to understand, but if you dont understand any points or have any other questions just let me know
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yorobun
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(Original post by derpz)
Progressive waves are longitudinal or transverse waves which basically transfer energy from one point to another. For example any wave out of the electromagnetic spectrum is progressive (e.g. visible light transfers energy in the form of light).Standing waves on the otherhand trap energy between two points. You also need to know how they are formed:Progressive waves are initially formed, which would travel in opposite directions, and then be reflected off whatever is keeping the medium together and when they reflect back, they interfere and form "nodes" and "antinodes".This might make it easier to understand:Here, the vibrator would have a certain frequency, which would first form a progressvie wave. This wave would then be reflected off the pulley and the vibrator as it travels along the string. It then interferes constructively and destructively.This is where "nodes" and "antinodes" come in.Constructive interference = Antinode formsDestructive interference = Node formsA node is the minimum aplitude on a standing wave. Here, it would be the points where it seems like the string interceps, as the amplitude is zero.An antinode is where the amplitude is maximum, which is the centre of the oval like shape formed, from the bottom to the very top.If that doesnt really make sense, this should:Also, a key difference is to remember that a standing wave has many amplitudes, whereas a progressive wave has only 1 amplitude which would be the max point. For example, on the standing wave any point between a node and antidnode is an amplitude but on a progressive wave these would just be points on the wave which have displacements.Here's a comparison between the two: I know my explanation is kind of hard to understand, but if you dont understand any points or have any other questions just let me know
"Standing waves on the otherhand trap energy between two points"are those the nodes and antinodes ? But notes have 0 amplitude so is it just antinode ?


"on the standing wave any point between a node and antidnode is an amplitude but on a progressive wave these would just be points on the wave which have displacements."
I don't really get what that means :\
I thought the amplitude was the displacement ?

So the string with the help of the vibrator would move in one direction at first(progressive wave) and then would be reflected back and when its reflected back its a standing wave ? so even the strings reflection counts as another oscillation ? so like 2 waves but one is just a reflection of the other ?

Sorry for the amount of questions x and thankyou ^-^
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derpz
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(Original post by yorobun)
"Standing waves on the otherhand trap energy between two points"
are those the nodes and antinodes ? But notes have 0 amplitude so is it just antinode ?



"on the standing wave any point between a node and antidnode is an amplitude but on a progressive wave these would just be points on the wave which have displacements."
I don't really get what that means :\
I thought the amplitude was the displacement ?

So the string with the help of the vibrator would move in one direction at first(progressive wave) and then would be reflected back and when its reflected back its a standing wave ? so even the strings reflection counts as another oscillation ? so like 2 waves but one is just a reflection of the other ?

Sorry for the amount of questions x and thankyou ^-^
Bascially standing waves have nodes at each end, so the progressive wave would reach those and reflect off whatever is holding it there and when they reflect back, they meet and interfere which causes the standing wave to form, so the main point to remember is that they are reflected and interfere.

The amplitude stuff is quite hard to explain but I will try my best to make it clear:
Name:  Untitled.png
Views: 1322
Size:  11.8 KB

On the diagram is a progressive wave, and you can see that from the minimum point (the horizontal line) to the peak is the amplitude. Now if we look at any of the other points (shown my the black dots), they are just points which have a displacement. So progressive waves only have 1 specific amplitude, and any other point is not an amplitude.

Now, looking at the standing wave below, we can see that the red dot that I've highlighted is what you would expect to be the only amplitude but its not a progressive wave so that is not the case.

On a standing wave, the black dots have their own amplitude. So basically think of it as any displacement for a point is the amplitude. It doesnt make much sense but I guess you just have to remember it that way.



So in summary:

Progressive waves have 1 amplitude, and standing waves have an amplitude at any point (which isnt the node because that has an amplitude of 0).

Looking at the last image you can also see that the energy would be trapped between the two outermost nodes which are against the wall.

I dont mind you asking questions since this is pretty confusing content, feel free to ask whatever
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yorobun
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(Original post by derpz)
Bascially standing waves have nodes at each end, so the progressive wave would reach those and reflect off whatever is holding it there and when they reflect back, they meet and interfere which causes the standing wave to form, so the main point to remember is that they are reflected and interfere.

The amplitude stuff is quite hard to explain but I will try my best to make it clear:
Name:  Untitled.png
Views: 1322
Size:  11.8 KB

On the diagram is a progressive wave, and you can see that from the minimum point (the horizontal line) to the peak is the amplitude. Now if we look at any of the other points (shown my the black dots), they are just points which have a displacement. So progressive waves only have 1 specific amplitude, and any other point is not an amplitude.

Now, looking at the standing wave below, we can see that the red dot that I've highlighted is what you would expect to be the only amplitude but its not a progressive wave so that is not the case.

On a standing wave, the black dots have their own amplitude. So basically think of it as any displacement for a point is the amplitude. It doesnt make much sense but I guess you just have to remember it that way.



So in summary:

Progressive waves have 1 amplitude, and standing waves have an amplitude at any point (which isnt the node because that has an amplitude of 0).

Looking at the last image you can also see that the energy would be trapped between the two outermost nodes which are against the wall.

I dont mind you asking questions since this is pretty confusing content, feel free to ask whatever

Thankyou so much xDI will make notes on what you said and do some more finding out , do you mind if I ask some more questions if I get confused again?You helped me a lot, thanks xD(I kind of get it now)
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derpz
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(Original post by yorobun)
Thankyou so much xDI will make notes on what you said and do some more finding out , do you mind if I ask some more questions if I get confused again?You helped me a lot, thanks xD(I kind of get it now)
No problem, feel free to ask more questions
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