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B What is a wave

  1. Mar 8, 2016 #1
    I'm going to begin studying about waves and sounds. But before I start I wanted help in understanding what really a wave is, I searched on google and YouTube and what I did understand was that waves are caused by a disturbance, due to that disturbance the potential energy gets converted to kinetic energy as energy starts moving ahead. What I don't understand is what is this wave made of? If waves and particles are different, then what exactly is a wave made of?
    Thank you :)
     
  2. jcsd
  3. Mar 8, 2016 #2

    ZapperZ

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    Do you have a textbook that is part of your beginning studies? If you do, what does it say? If you don't, how are you studying all this? Using random things you find online?

    Zz.
     
  4. Mar 8, 2016 #3

    ProfuselyQuarky

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    A wave is pretty much a form in which energy is transferred without the presence of matter. There are ultimately two different types of waves: transverse waves and longitudinal wave. The primary difference between the two is that transverse waves can be polarized but longitudinal ones cannot be. A polarized wave vibrates in a single plane.
     
  5. Mar 8, 2016 #4
    In my opinion the best way to think about "what a wave is" is geometrically. In the most basic sense a wave is an abstract geometrical object that moves in some particular fashion. The wave itself is not "made of" anything. The wave is just a description of how some geometrical distortion in a medium propagates. The "wave versus particle" question isn't really interesting until you start talking particularly about electromagnetic waves. If your question is what electromagnetic waves are made of, then this is a sort of deep quantum mechanics question that nobody has a perfect answer to yet. But if we forget about that and just focus on basic mechanical waves, like sound waves or water waves or waves on a string, then the answer is straightforward: waves are propagating geometrical disturbances in a medium (moving shapes), and the medium is made of particles (presumably some kind of molecules).

    Mathematically, the general representation of a wave is some function of the form f(x-vt), where x is a spatial variable and t is a time variable.
     
  6. Mar 8, 2016 #5
    I've a textbook. I'm doings IGCSEs right now. The thing is that the textbook doesn't really give much reasoning behind why things are the way they are. I know how to calculate the speed, wavelength, frequencies and etc. But I don't like to learn the rules before seeing the game. :)
     
  7. Mar 8, 2016 #6

    davenn

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    well that makes it really difficult for you to learn
    it would be a really good idea to start changing your mindset on that :wink:
     
  8. Mar 8, 2016 #7
    Honestly, knowing the why's and how's to the what's helps me understand better. :)?
     
  9. Mar 8, 2016 #8
    so energy causes distortion in a medium, and the medium carries the energy in a particular fashion similar to the initial distortion caused by energy? Another question :p what happens to sound energy after a certain distance? What does it convert into?
     
  10. Mar 8, 2016 #9
    Heat, I would think. That's to say, random motion of the surrounding air molecules.
     
  11. Mar 8, 2016 #10
    If you don't know the rules you won't understand the game. Especially if the game IS the rules. :)
     
  12. Mar 8, 2016 #11

    Drakkith

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    I think the best explanation of a wave I've ever heard was, "A wave is that which obeys the wave equation".
     
  13. Mar 9, 2016 #12
    ^corrected myself lol
     
  14. Mar 11, 2016 #13

    ProfuselyQuarky

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    That's sure helpful, Drakkith :smile:
     
  15. Mar 11, 2016 #14
    Any object can probably be put in this form, as seen from a moving frame of reference.
    A wave is a travelling oscillation.
     
  16. Mar 11, 2016 #15

    sophiecentaur

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    Not all waves have a wavelength. because they are not always periodic. Probably an improvement would be 'a travelling disturbance'. This would then include single pulsed waves or the propagation of a 'step' transition.
     
  17. Mar 11, 2016 #16
    Waves are just a general term to describe the propagation of energy and momentum. Some waves are periodic and represent oscillations, some are not. They are the natural way in which energy and momentum spread out and move in continuous mediums, based on the laws of nature we happen to live with.
     
  18. Mar 11, 2016 #17
    Can I think of it as a set of dominos? Where one disturbance, creates a chain travelling along?
     
  19. Mar 11, 2016 #18

    Drakkith

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    Thanks. I'm here for you, after all! :-p
     
  20. Mar 11, 2016 #19
     
  21. Mar 12, 2016 #20
    The oscillation involves a displacement and a return force, which in general is nonlinear. If oscillations in one place are coupled to the next place, a travelling oscillation can result. This covers even the case of falling domino pieces. The only problem I see with this definition is that it requires a medium, so it begs the in my opinion unavoidable question: what is the medium for EM waves ?
     
    Last edited: Mar 12, 2016
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