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We know that waves are of two types: transverse and longitudinal, and we have studied about de Broglie waves as well,

  • so which one of them is it? Or we have other means to classify them?
Ellie
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Alok Subedi
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2 Answers2

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we all know waves are of two types transverse and longitudinal, and we do have studied about de broglie wave as well,so which ond of them is it?. or we have other means to classify them..

For a wave to be either transverse of longitudinal it must be a vector field quantity (e.g., the electric field). This is because "transverse" means that the vector quantity (e.g., the electric field) is perpendicular to the wave-vector (the direction the wave is moving), and "longitudinal" means that the vector quantity is parallel to the wave-vector.

A de broglie wave is a scalar wave not a vector wave so it does not make sense to ask if the quantity itself is perpendicular or parallel to anything. Therefore a de broglie wave is neither "transverse" nor "longitudinal", it is a scalar wave.

hft
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  • Whoops. Misread the answer. (deleted comment) – garyp Apr 14 '15 at 17:19
  • So you mean this is probability wave and here probability is changing with time and space which is a scalar?right? – Paul Jul 08 '15 at 04:40
  • Nope. Time and space are the arguments to the function. I'm talking about the value of the function, the value of the function is a scalar not a vector. The value of the function is a single number (a probability amplitude) which is not a vector, it's a scalar. – hft Jul 08 '15 at 20:42
  • What is really oscillating in this wave? like in light wave electric and magnetic field oscillating. – Paul Jul 11 '15 at 14:25
  • The probability amplitude is oscillating. – hft Jul 11 '15 at 21:42
  • De Broglie Hypothesis relates the wavelength with the momentum as λp = h. How can we measure the wavelength of a wave that's neither transverse nor longitudinal? – Shub May 14 '21 at 13:14
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An electromagnetic wave is a transverse wave, and we can make an electron and a positron out of it in pair production. Then we can diffract the electron, and even refract it. We can also polarize electron beams. Then we can annihilate the electron with the positron, and get two or three electromagnetic waves, which are transverse waves. So the hard scientific evidence is pointing us towards transverse waves. OK, see what hft said above about the electric field being perpendicular to the direction the wave is moving? Have a look at a depiction of the electron's electric field from Andrew Duffy's physics course. It's the one on the right:

enter image description here

Now think of electron spin and spinors and the Einstein-de Haas effect which "demonstrates that spin angular momentum is indeed of the same nature as the angular momentum of rotating bodies as conceived in classical mechanics". Then ask yourself this: in what direction does the wave have to be going to be perpendicular to the electric field? IMHO the answer is obvious: round and round. Hence in atomic orbitals electrons "exist as standing waves". See this image courtesy of Grandinetti:

enter image description here

The inference is that the wave is in some spherical-harmonic closed path. Round and round, as it were. With this in mind the electron not only has a definite wave nature, but IMHO it has a definite transverse wave nature too. And since the electron is matter, IMHO the inference is that matter waves are transverse waves.

John Duffield
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