Is the distance between a trough and crest one wavelength?

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Discussion Overview

The discussion revolves around the definition of wavelength in relation to the distance between a trough and a crest in waveforms. Participants explore this concept in the context of both pure sine waves and more complex waveforms, addressing theoretical and conceptual aspects of wave behavior.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that the distance between a trough and a crest is half a wavelength.
  • Others argue that one wavelength is defined as the distance from trough to trough or crest to crest.
  • There is a discussion about the nature of waves, with some noting that many real-world waves are not pure sine waves, which complicates the definition of wavelength.
  • One participant expresses uncertainty about the phase relationship between points at the crest and trough.
  • Another participant provides a resource to illustrate the differences between sine waves and complex waves, emphasizing the challenges in discussing troughs and crests in non-sine wave contexts.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the distance between a trough and a crest constitutes one wavelength, with multiple competing views presented regarding the definition of wavelength in different types of waves.

Contextual Notes

Participants acknowledge that the discussion is complicated by the presence of complex waves, which may contain multiple local crests and troughs within a single wavelength, and that definitions may depend on the specific type of wave being considered.

TheShapeOfTime
Is the distance between a trough and crest one wavelength?
 
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No, 1 wavelength is trough to trough or peak to peak.
 
Last edited:
TheShapeOfTime said:
Is the distance between a trough and crest one wavelength?
It seems that you're thinking about a pure sine wave, in which case the wavelength is the distance between crests (or troughs). But waves are not sine waves in general. If its a complex wave (as many waves in the real world are) then there may be many local crests (or troughs) within one wavelength.

Pete
 
Last edited:
TheShapeOfTime said:
Is the distance between a trough and crest one wavelength?

That would be a HALF wavelength!
 
Yeah I was thinking the samething when I first read it. Its the distance beteen two consecutive crest or troughs.
 
Tide said:
That would be a HALF wavelength!

I was thinking this too, but I wasn't sure if a point at the top of a crest was considered in phase with one at the bottom of a trough.

pmb_phy said:
It seems that you're thinking about a pure sine wave, in which case that is correct. But waves are not sine waves in general. If its a complex wave (as many waves in the real world are) then there may be many local crests and troughs within one wavelength.

I've only just been introduced to waves so I have no idea what sine or complex waves are. :redface:
 
Tide said:
That would be a HALF wavelength!
Oy vey! Yes. True. How did I miss that?
TheShapeOfTime said:
I've only just been introduced to waves so I have no idea what sine or complex waves are.
Take a look at this web site. It'll give you an idea.

http://www.udel.edu/idsardi/sinewave/sinewave.html

Uncheck "red" and "sum" and the result is a sine wave. Now check "red" and it will plot another sine wave on the same axis. Now check "sum" and you'll see the function which is the sum of the two which is a wave, but not a sine wave. Uncheck "blue" and "sum" and you'll see only the sum (the "complex"/"non-simple" wave). See the problem of speaking about troughs and crests?

Note: By "complex" I don't mean anything to do with complex numbers. I mean "not a simple sine wave."

Pete
 

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