zahrah446
Badges: 7
Rep:
?
#1
Report Thread starter 10 months ago
#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
0
reply
Brain Damage
Badges: 13
Rep:
?
#2
Report 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
reply
zahrah446
Badges: 7
Rep:
?
#3
Report Thread starter 10 months ago
#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
reply
Brain Damage
Badges: 13
Rep:
?
#4
Report 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?
0
reply
zahrah446
Badges: 7
Rep:
?
#5
Report Thread starter 10 months ago
#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.
Name:  IMG_1639.JPG
Views: 57
Size:  112.0 KB
I'm sorry for being so difficult to explain to. Thanks a lot!
0
reply
Brain Damage
Badges: 13
Rep:
?
#6
Report 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
reply
zahrah446
Badges: 7
Rep:
?
#7
Report Thread starter 10 months ago
#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
reply
Brain Damage
Badges: 13
Rep:
?
#8
Report 10 months ago
#8
No problem
(Original post by zahrah446)
I totally understand now. Thank you so much.
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

University open days

  • University of Hertfordshire
    All Subjects Undergraduate
    Sat, 22 Feb '20
  • Ravensbourne University London
    Undergraduate Open Day Undergraduate
    Sat, 22 Feb '20
  • Sheffield Hallam University
    Get into Teaching in South Yorkshire Undergraduate
    Wed, 26 Feb '20

People at uni: do initiations (like heavy drinking) put you off joining sports societies?

Yes (409)
67.83%
No (194)
32.17%

Watched Threads

View All