# Standing WavesWatch

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#1
I just studied destructive interference and now I don't get standing waves. How are antinodes produced when the whole thing should be a minimum since the phase difference between the two progressive waves is 180 degrees?
And how is the phase difference at different points between the two progressive waves in a standing wave calculated?
I'm finding it very confusing and any help would be appreciated.
Last edited by zahrah446; 10 months ago
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10 months ago
#2
I found this hard at first too. See if this animation helps.

https://www.walter-fendt.de/html5/ph...lection_en.htm

The phase difference between an even number of nodes is 0. Between an odd number of nodes it's 180
1
#3
The animation finally helped me understand after months of studying about standing waves. Thanks a lot!
I just have one more question: what did you mean by even and odd number of nodes?
(Original post by Brain Damage)
I found this hard at first too. See if this animation helps.

https://www.walter-fendt.de/html5/ph...lection_en.htm

The phase difference between an even number of nodes is 0. Between an odd number of nodes it's 180
0
10 months ago
#4
Take a look at this image.

https://cdn.discordapp.com/attachmen...42/unknown.png

I've marked the nodes in blue, so let's go over this with some examples.
There are 0 nodes between C and A. 0 is even so the phase difference is 0.
There's 1 node between A and B. 1 is odd, so the phase difference is 180.
There's 2 nodes between A and A1. 2 is even so the phase difference is 0.

Get the idea?
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#5
(Original post by Brain Damage)
Take a look at this image.

https://cdn.discordapp.com/attachmen...42/unknown.png

I've marked the nodes in blue, so let's go over this with some examples.
There are 0 nodes between C and A. 0 is even so the phase difference is 0.
There's 1 node between A and B. 1 is odd, so the phase difference is 180.
There's 2 nodes between A and A1. 2 is even so the phase difference is 0.

Get the idea?
Wait but isn't the definition of phase difference 'the difference between some references point in 2 waves- it is how much one wave is shifted from the other'? Of so, there is only 1 wave in that attachment, so what would be the definition of phase difference in this case?

My question was regarding the phase difference on different points between the two progressive waves in a standing wave. Can you please explain this to me? The correct answer is B.

I'm sorry for being so difficult to explain to. Thanks a lot!
0
10 months ago
#6
My bad. Thought we were talking about 2 points on the same standing wave.

I'll go over this question, tell me if it makes sense then.

At X, you have a node on the standing wave. This means that the 2 progressive waves cancel each other out completely at this point. This means that they are antiphase.
At Y, you have an antinode. This means that the waves reinforce each other completely at this point. They're in phase, so their phase difference is 0 radians. 2 pi radians is the exact same as 0 radians because there are 2 pi radians in a full wavelength.

Edit:
You can have a phase difference between the same point on 2 different waves, or 2 different points on the same wave.
Last edited by Brain Damage; 10 months ago
0
#7
(Original post by Brain Damage)
My bad. Thought we were talking about 2 points on the same standing wave.

I'll go over this question, tell me if it makes sense then.

At X, you have a node on the standing wave. This means that the 2 progressive waves cancel each other out completely at this point. This means that they are antiphase.
At Y, you have an antinode. This means that the waves reinforce each other completely at this point. They're in phase, so their phase difference is 0 radians. 2 pi radians is the exact same as 0 radians because there are 2 pi radians in a full wavelength.

Edit:
You can have a phase difference between the same point on 2 different waves, or 2 different points on the same wave.
I totally understand now. Thank you so much.
0
10 months ago
#8
No problem
(Original post by zahrah446)
I totally understand now. Thank you so much.
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