Aaradhana
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"All points in between two nodes on astanding wave are in phase whereas points on a progressive wave that are closer than one wavelength are all out of phase". How?

Some points on a node between the wave are above the other points, on a stationary wave, so how are all the points in phase?
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Stonebridge
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(Original post by Aaradhana)
"All points in between two nodes on astanding wave are in phase whereas points on a progressive wave that are closer than one wavelength are all out of phase". How?

Some points on a node between the wave are above the other points, on a stationary wave, so how are all the points in phase?

Can you see the animation at the bottom of my post?
It shows a standing wave. (The third, blue, wave)
All the points between any two nodes are moving up and down together. (In phase.)

V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V
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Aaradhana
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(Original post by Stonebridge)
Can you see the animation at the bottom of my post?
It shows a standing wave. (The third, blue, wave)
All the points between any two nodes are moving up and down together. (In phase.)

V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V V
I can't see your animation... I can only see the photo but in any case, even though the points are moving up and down together (take a skipping rope) they aren't moving up and down to the same extent right? Some are moving little up and others are moving more up... so can they be said to be in phase?
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Stonebridge
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Can you see this wave here
V V V V V V V
Image

This is a standing wave with two antinodes.
The blue square is going up and down.
If you imagine a second square on the wave just to the right of that blue square, it too would be going up and down in time with the 1st square.
Yes they are not going up and down exactly the same amount (different amplitude) but they are going up and down together. This means they are in phase. They don't have to have the same amplitude, but they must move up together, down together and stop together.
By the way, in other half of the wave, the red square is in antiphase (180 degs out of phase) with the blue square.
This is what happens on a standing wave. In each antinode section all the points are in phase. They are all out of phase with the points in the next antinode to the left or right.
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Kolasinac138
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(Original post by Stonebridge)
Can you see this wave here
V V V V V V V
Image

This is a standing wave with two antinodes.
The blue square is going up and down.
If you imagine a second square on the wave just to the right of that blue square, it too would be going up and down in time with the 1st square.
Yes they are not going up and down exactly the same amount (different amplitude) but they are going up and down together. This means they are in phase. They don't have to have the same amplitude, but they must move up together, down together and stop together.
By the way, in other half of the wave, the red square is in antiphase (180 degs out of phase) with the blue square.
This is what happens on a standing wave. In each antinode section all the points are in phase. They are all out of phase with the points in the next antinode to the left or right.
By the way, you said that the double slit formula can only be used for a double slit, how about n*lambda=dsintheta, can that be used for all diffraction gratings?
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Stonebridge
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(Original post by Kolasinac138)
By the way, you said that the double slit formula can only be used for a double slit, how about n*lambda=dsintheta, can that be used for all diffraction gratings?
Well that's the diffraction grating formula and as far as I know applies to all diffraction gratings.
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Kolasinac138
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(Original post by Stonebridge)
Well that's the diffraction grating formula and as far as I know applies to all diffraction gratings.
So even one with 5000 slits?
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Aaradhana
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(Original post by Stonebridge)
Can you see this wave here
V V V V V V V
Image

This is a standing wave with two antinodes.
The blue square is going up and down.
If you imagine a second square on the wave just to the right of that blue square, it too would be going up and down in time with the 1st square.
Yes they are not going up and down exactly the same amount (different amplitude) but they are going up and down together. This means they are in phase. They don't have to have the same amplitude, but they must move up together, down together and stop together.
By the way, in other half of the wave, the red square is in antiphase (180 degs out of phase) with the blue square.
This is what happens on a standing wave. In each antinode section all the points are in phase. They are all out of phase with the points in the next antinode to the left or right.
Thanks a lot!
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Stonebridge
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(Original post by Kolasinac138)
So even one with 5000 slits?

Why should "5000 slits" be a problem?
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