Why do we see 2 waves in interference instead of 3 or 4?

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    Interference Optics
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Discussion Overview

The discussion revolves around the concept of wave interference, specifically why calculations often focus on two waves rather than three or more. Participants explore the implications of using different numbers of waves in determining conditions for maxima and intensity.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions why interference calculations typically consider only two waves, suggesting that using three waves would yield different results.
  • Another participant points out that while two-wave interference is common, it is indeed possible to analyze scenarios involving multiple waves, such as in multiple-slit interference and diffraction.
  • A response clarifies that the choice of using two waves is often for simplicity in calculations, especially in educational contexts, while acknowledging that more complex situations can involve three or more waves.
  • One participant emphasizes the distinction between "two waves" and "two sources," indicating that a more detailed analysis would consider groups of waves from each source rather than just pairs.

Areas of Agreement / Disagreement

Participants express differing views on the necessity and implications of using two versus three waves in interference calculations. There is no consensus on a definitive approach, as the discussion highlights both the simplicity of two-wave analysis and the complexity introduced by additional waves.

Contextual Notes

Limitations include the assumption that simpler calculations are preferable for learning, and the dependence on specific experimental setups, such as the Young's fringe experiment, which may influence the choice of wave count in analysis.

prashantgolu
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why do we see 2waves when we consider interference ?why not three or four?eg when we find out conditions formaxima we look for condition when 2 waves interefere...why not 3?
 
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It's certainly possible to consider more than two waves interfering. In my optics course I cover examples such as multiple-slit interference. And any diffraction situation (e.g. single-slit diffraction) is basically an infinite number of waves superposing together, which you analyze by integration rather than by simple addition.
 
what i meant is that we calculate the condition for maxima by taking 2 waves interefering but if we do by 3 waves then surely answer will be different...so why do we do by taking 2 waves
 
It depends on the situation. If there are 2 waves present, we calculate using 2 waves. If 3 waves are present, we must use all 3 waves.

If you are referring to physics homework problems, we use 2 waves because that is easier to calculate and we want you to learn the basic principle by doing simpler calculations.
 
sorry i couldn't get you people to make it simple i was saying that we find net intensity at a point by finding net intensity between 2 waves why not threee why are we breaking waves in pairs why not in 3 waves in a group?
 
prashantgolu said:
sorry i couldn't get you people to make it simple i was saying that we find net intensity at a point by finding net intensity between 2 waves why not threee why are we breaking waves in pairs why not in 3 waves in a group?

Hello prashantgolu,I think you are confusing "two waves" with "two sources".In the simplest analysis of the Youngs fringe experiment we might,for example,consider just two waves only,one from each source, to find the position of the maxima caused by these two waves.There is,however, a whole group of waves from each source and a more detailed analysis which accounts for the intensity variation across the maxima and minima would consider these whole group of waves.If there were three sources there would be three groups of waves and so on.
 
thank u
 

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