# What is Debroglie: Definition and 44 Discussions

Matter waves are a central part of the theory of quantum mechanics, being an example of wave–particle duality. All matter exhibits wave-like behavior. For example, a beam of electrons can be diffracted just like a beam of light or a water wave. In most cases, however, the wavelength is too small to have a practical impact on day-to-day activities.
The concept that matter behaves like a wave was proposed by French physicist Louis de Broglie () in 1924. It is also referred to as the de Broglie hypothesis. Matter waves are referred to as de Broglie waves.
The de Broglie wavelength is the wavelength, λ, associated with a massive particle (i.e., a particle with mass, as opposed to a massless particle) and is related to its momentum, p, through the Planck constant, h:

λ
=

h
p

=

h

m
v

.

{\displaystyle \lambda ={\frac {h}{p}}={\frac {h}{mv}}.}
Wave-like behavior of matter was first experimentally demonstrated by George Paget Thomson's thin metal diffraction experiment, and independently in the Davisson–Germer experiment, both using electrons; and it has also been confirmed for other elementary particles, neutral atoms and even molecules.

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1. ### Finding Broglie wavelength after acceleration

KE = 100eV x (1.6x10^-19) v(new) = √(2KE/9.1×10^-31 ) = 5.9x10^6m/sv(original) = h/λm = 6.6x10^-34 / (0.2x10^-9 x 9.1x10^-31) = 3.64x10^6m/s
2. ### I Viewing the wave properties of a macroscopic object

My textbook explained that it would be hard to see the wavelength properties of a tennis ball because we would have to find a very tiny slit in which to pass the tennis ball through. The wavelength of the tennis ball can be calculated using debroglie formula: wavelength = h/p I was wondering if...
3. ### Studying De Broglie-Bohm theory books/material recommendations....

Hi PF, im finishing my bachelor soon and I would really like to do my thesis in De Broglie-Bohm theory. I know its a controversial topic but i refuse to accept the statistical crazyness of qm(i passed qm already). Im not a super good student so I´m asking you for some books on this theory, or...
4. ### Wavelength = deBroglie Wavelength?

Homework Statement Find the retarding potential required to stop electron of de-broglie wavelength 0.5 nm Homework Equations 1)de-broglie wavelenght=h/momentum 2)eV=KE of electron 3)KE=p^2/2m The Attempt at a Solution Using the above three relations is giving me an incorrect answer for V...
5. ### I Energy-momentum formula and deBroglie wavelength

Hi everyone, Im a little bit confused about deBroglies procedure on introducing his famous Matterwave formula. People already knew that the wavelength of the light was equal to Lambda = h/p. The term p comes from the energy-momentum formula; for the light the restmass = 0 so E =pc etc. As...
6. ### I DeBroglie wavelength & particle-wave duality

We are told to exorcise wave-particle duality because it belongs to the past, in fact prior to 1927. So it’s acceptable to believe matter is neither wave nor particle. But in exorcising wave-particle duality. Why does the deBroglie relationship of momentum being inversely proportional to...
7. ### Why is deBroglie λ for electrons the same as λ for photons?

Hi, I got the following question in my textbook: [translated]"Compare the wavelength of a photon and an electron where the photon and the electron have the same momentum". My thinking is the following: Firstly, pp (photon) = pe (electron). My textbook briefly mentions the extention of the...
8. ### DeBroglie wavelength based on kinetic energy

Homework Statement I am working on a problem similar to this one: In this solution, I do not understand what mc is, can someone explain? Also, would I follow the same type of steps if I have the kinetic energy of a photon and I need it's wavelength? Homework EquationsThe Attempt at a Solution
9. ### I Underlying reality re deBroglie equation

While the mathematics and the experimental results of de Broglie's equation are clear, what is the best understood explanation as to what is happening in underlying reality of why wavelength varies (inversely) with momentum for all energy and matter ?
10. ### I Question about the deBroglie hypothesis

Hi, I am a new member here : ) I have always wondered about this. It seems that the answer is easy but I missed an important lecture. De Broglie proposed that just as light has both wave-like and particle-like properties, electrons also have wave-like properties. Why is that? I know the relation...
11. ### B Electron Diffraction and the DeBroglie Wavelength

I've been reading up on electron diffraction for electron microscopy, and I have been trying to understand the proof for the wavelength of an electron in a tunneling electron microscope. The proof I have been trying to emulate begins as follows: It then says that I must account for...
12. ### B Exploring DeBroglie Wavelength and Its Impact on Dark Matter

deBroglie wavelength says that wave-like properties of object or particle is inversely proportional to mass. Since dark matter has so very few tiny micro iota of mass.. does it mean the wave-like properties of dark matter (should this really exist) are more enhance and closer to quantum objects?
13. ### Finding the deBroglie wavelength: conceptual issue

Hello all! I am new to this forum, though I have been lurking for a long time. I intend to fill out my profile and introduce myself, but finals leave me with little time to spare at the moment. I have this final next week and would like to sort this out beforehand, hence the hasty post! Thank...
14. ### I The Debroglie Relation and SR?

The function ei(p.r – Et) is the central player in non-relativistic QM. Yet the expression (p.r – Et) is the Minkowski inner product of the space-time four-vector, (t,r), and the four-momentum (E,p) and as such is Lorentz invariant. According to Feynman, De Broglie realized the relativistic...
15. ### B DeBroglie Wavelength with Relativistic Electron

I am trying to find the DeBroglie wavelength of an electron moving at .8c. I have never learned special relativity but I believe the momentum is affected (mass change). I used the formula p= (mv)/(1-v^2/c^2) and got a momentum of p = 2.733 E-22 and a wavelength of lamda = 2.4149 E-12. Did I...
16. ### DeBroglie wavelength of Proton in H atom

How would one calculate the de Broglie wavelength of the proton in the hydrogen atom as the electron and proton pirouette around their common center of mass, for the lowest orbital? I believe the center-of-mass of the system would actually be inside the proton due to the great differential in...
17. ### DeBroglie equation applied to atoms & molecules: not so obvious

One of the first things about QM we were taught in my undergraduate physics program is the deBroglie relation: λ = h/p Now, it makes sense that that this might hold for all elementary particles, especially since the evidence generally seems to suggest that the commonly observed forms of...
18. ### Why do all particles have a wavelength?

So for my AS specification I need to know how to use the debroile wavelength equation which is fair enough and easy. I was wondering if anyone could tell me why do all particles have a wavelength or wave function? Or even like a tennis ball? Thanks, PS: I know it's a weird question...
19. ### What does a deBroglie wave look like?

Are deBroglie waves transverse or longitudinal? Can they be polarized? What about the deBroglie wave of a ground state neutral spin-zero Helium 4 atom? What experimental evidence do we have that supports the detailed nature of a deBroglie wave? I have always assumed that deBroglie waves...
20. ### Reconciling DeBroglie and Dirac?

So in 1927 Davisson and Germer showed that electrons shot at a crystal do indeed have a DeBroglie wavelength inversely proportional to their momentum (h/p)? That would mean that their wavelength is a function of their velocity, the voltage used to accelerate them, etc. But I seem to remember...
21. ### DeBroglie wavelength in infinite potential well

nvm i figured it out. it was not in reference to n=4. equation used would be wavelength = 2L/n Homework Statement An electron is in an infinite potential well of width L. Which is not an allowed deBroglie wavelength for the electron to have when n=4? wavelength(k) = 3L, 2L, L/2, or L/3Homework...
22. ### Debroglie Wavelength: λ & v Proportional?

According to Debroglie Eq λ=h/mv λ and v inversely proportional to each other.But according to eq v=f*λ they seem to be directly proportional.So what is the actual dependence of lambda on v?
23. ### DeBroglie matter waves and double-slit

Homework Statement A beam of electrons with a kinetic energy 1.00 MeV strikes normally at an array of atoms separated by 0.25 nm. in what direction can we expect the electrons in the fifth order? Homework Equations Ek= hf - W p=h/λ dsinθ=nλ The Attempt at a Solution i tried my...
24. ### DeBroglie Wavelength: Proton at Room Temp Scattering Behavior

A proton at room temperature with an energy of 0.025eV has a deBroglie wavelength of about 1A (1E-10 meters). If we shoot two proton beams at each other with is low energy and large wavelength what happens? Do they scatter as if they are small hard particles of size about 1 fermi (1E-15 meters)...
25. ### DeBroglie wavelength, kE to (p) conversion?

I have a relatively simple question. I should know this, but... I need to solve for the deBroglie wavelength when only the kinetic energy is known. Shouldn't I be able to convert kE to momentum (p), when the object does not have a known velocity or mass...? Much thanks... JD
26. ### DeBroglie wavelength and nucleon velocity

Homework Statement Atomic nucleus consists of nucleons. What velocity (order of magnitude estimate) will a nucleon have inside a nucleus? Homework Equations \lambda = h/mv v = h/m\lambda The Attempt at a Solution The wavelength of a nucleus is on the order of 10^-15/m...
27. ### Calculating the momentum of a debroglie wave from its wave function

I want to calculate the momentum of the wave given by psi = Asin(8.92e10 x) where x is in metres. I know that momentum = planks/wavelength, but I'm unsure of how to get any information out of the wavefunction alone... any guidance would be appreciated. mitch
28. ### Calculate DeBroglie Wavelength & Kinetic Energy of Electron

Homework Statement What is the DeBroglie wavelength of an electron whose energy is (a) 1.0eV (b) 100eV? What is the kinetic energy in eV of an electron whose DeBroglie wavelength is that of visible red light at 650nm? Homework Equations λ=h/p = h/mv h = Planck's constant...
29. ### Photoelectric: deBroglie

Homework Statement A photocathode whose work function is 2.9 eV is illuminated with white light that has a continuous wavelength band from 400 nm to 700 nm. A) What is the threshold frequency for photoelectron production? a. 4 x 1014 Hz b. 7 x 1014 Hz c. 13 x 1014 Hz B) What is the...
30. ### DeBroglie Wavelength: Solving for Electrons in Relativity

Homework Statement An electron of charge e and rest mass m0 is accelerated to relativistic speeds by a potential V. Show that the deBroglie wavelength is given by the expression lambda= h(2m0eV)-1/2 (1+eV/2m0c2)-1/2 The Attempt at a Solution eV = gamma m0c2 equation one p = gamma...
31. ### Debroglie Wavelength Homework: Proton and Alpha Particle Ratio

Homework Statement The momentum of a proton and an alpha particle are equal. The mass of alpha particle is 4 times the mass of proton. The ratio of wavelength associated with them is ---- Homework Equations \lambda = h / p The Attempt at a Solution if the momentum are equal then...
32. ### Questions about deBroglie (matter) waves

I'd like to ask some questions about deBroglie waves. (1) are deBroglie waves a topic under classical physics, or does it belong under quantum mechanics, or relativity? (2) The justification for deBroglie expecting matter waves is "well, photons have frequency and wavelength, so it only...
33. ### DeBroglie wavelength for particle at rest

lambda = h/mv v -> 0 means lambda is -> infinite? So if I have an old pickup truck that moves really slow, its matter wave is huge, right?? So it's now a wave and not a particle?
34. ### DeBroglie and Time Dilation Paradox

I need someone to resolve this paradox for me. Before I start, here are the basic ideas: Okay, so every moving particle has a DeBroglie wavelength: E=hc/\lambda. This also means that each particle has a frequency: E=hf So it also has a period: E=h/\tau So any given mass has a DeBroglie...
35. ### DeBroglie Wavelength Comparison

Homework Statement Compare the deBroglie wavelength for an electron in the n=6 orbit of He+ compared to the n=2 orbit. Is the deBroglie wavelength the same, smaller, or larger? Derive this. Homework Equations Quantization of Paths of Electrons: 2 pi r = n (lambda) Bohr Radius: rn=n2 aB The...
36. ### Electron and deBroglie wavelength

Homework Statement An electron moves in the x direction with the de Broglie wavelength 10^-8 cm. a) What is the energy of the electron in (eV)? b) What is the time-independent wavefunction of the electron? Solution? a) We have p = h/2pi * k = h/2pi * 2pi / lambda. So, p = h /...
37. ### The difference between Compton and DeBroglie wavelengths?

Hi. As you can see, the question is pretty straightforward. What is the difference between the Compton and the DeBroglie wavelength? I have looked into Wikipedia and other sites but I'm still somewhat confused. Thanks.
38. ### DeBroglie wavelength / particle phys

Would anybody be able to advise how I would approach the following question? I know the deBroglie wavelength is h/p, but I'm unsure how to calculate p based on the kinetic/total energy...
39. ### Mathematica Exploring the deBroglie Function: Understanding Its Mathematical Signature

I asked a similar question ihttps://www.physicsforums.com/showthread.php?t=171030", but got the suggestion to come here: The electromagnetic field, as solution of the Maxwell equations, has the signature \def\R{\mathbb{R}}f:\R^4\to \R^3\times \R^3, indicating that each point in 4D spacetime...
40. ### Find de Broglie Wavelength of 7.0 eV Electron

Homework Statement Find the de Broglie wavelength of a 7.0 eV electron.Homework Equations de Broglie wavelength = h/p = h/(mv) Photoelectric effect equation (not 100% sure) The Attempt at a Solution i need to solve for v in de Broglie's equation so i can find the wavelength. i know the mass of...
41. ### DeBroglie wavelength considering relativistic effects

"Electrons are accelerated by a potential of 350kV in an electron microscope. Calculate the de Broglie wavelength of those electrons taling relativistic effects into account" I attempted the following: W = W(kin) = 350keV now W(kin)= (1-gamma)mc^2 so, now one could solve for...
42. ### Debroglie wavelength of a baseball

ok can someone please explain to me why this is wrong? debroglie of a baseball weighing 1kg is h/(1kg * v). You through this at a double slit at 10^-34 m/s which makes the wavelength equal to 6.63 meters. for a double slit its d*sin(theta) = m * (wavelength) so you get theta = sin^-1(6.63/d)...
43. ### Debroglie Wavelength: Trapped Particle's Lamda=2L/n

why is the debroglie wavelength of a trapped particle equal to lamda=2L/n?
44. ### DeBroglie wavelength its due at 12am

The deBroglie wavelength of an electron which moves with a speed of .0320 c is 7.18x10^-12 What is the fundamental minimum uncertainty in a measurement of the position of the elctron in the previous prolem if its momentum is simultaneouslymeasured to a precisioin of plus or minus one percent...