What Are Standing Waves and How Do Their Amplitudes Relate to Intensity?

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Discussion Overview

The discussion revolves around the concept of standing waves, specifically focusing on the relationship between amplitude and intensity. Participants explore definitions, properties, and the implications of amplitude in the context of standing waves, addressing both theoretical and conceptual aspects.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant defines standing waves as the result of two waves of equal amplitude traveling in opposite directions, leading to no energy propagation.
  • Another participant points out that if the amplitude is zero due to superposition, it implies the waves are out of phase, suggesting that there is no resultant wave to discuss in terms of intensity.
  • A participant explains that amplitude in standing waves can refer to the oscillation at specific points, which varies along the wave, being zero at nodes and maximum at antinodes.
  • There is a clarification attempt regarding the maximum amplitude of oscillation, with confusion arising about whether it refers to nodes or antinodes.
  • One participant asserts that the maximum amplitude of oscillation should indeed be at an antinode, correcting a previous statement.

Areas of Agreement / Disagreement

Participants express confusion and seek clarification on the definitions and properties of amplitude in standing waves. There is no consensus on the relationship between amplitude and intensity, as well as the correct interpretation of amplitude at nodes versus antinodes.

Contextual Notes

Participants highlight the need for clearer definitions and distinctions between different types of amplitude in standing waves, indicating potential misunderstandings in terminology.

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Hi all,actually i want to discuss about standing wave. Its little bit confusing to me.As a simple definition,when two waves of equal amplitude travel in opposite direction then what the resultant wave,for which there is no propagation of energy is called standing waves.
But another property says that amplitude at each point in space stays constant and more the amplitude,more intense is the wave.Now question arises,If we are getting zero amplitude by superposition of 2 waves of equal amplitude,then what type of amplitude that is being discussed here. and we are saying that that all points have zero amplitude then how could we relate the intensity to amplitude.
Please reply,hope you have understand the question.
thanks
 
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Your question is a bit vague. If you are getting an amplitude of zero after superposition of two waves of equal amplitude, that means the two waves are exactly out of phase: the peaks cancel out the troughs exactly, like in the second (right-most) image here:
Interference_of_two_waves.png


If this is the case, there is no resultant sound wave and you cannot speak of its intensity.
 
There are two ways in which the word "amplitude" can be used in a standing wave. First, each point on the wave oscillates with some amplitude, which varies from one position to another along the wave. This amplitude is zero at a node and maximum at an antinode. Second, the standing wave as a whole has an amplitude which is the maximum amplitude of oscillation of any point on the wave, i.e. the amplitude at a node. [added: oops, I should have said "antinode" here.]
 
Last edited:
Hi jtbell,thanks for your response,but it is still confusing.On one side you said that amplitude is zero at a node and maximum at an antinode. On other side you said that ,the standing wave as a whole has an amplitude which is the maximum amplitude of oscillation, i.e. the amplitude at a node.
So kindly can you differentiate this.
 
I am pretty sure jtbell means the maximum amplitude of oscillation is at an antinode.
 
Oops yes, I meant the amplitude at an antinode. :blushing:
 

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