De broglie Definition and 266 Threads

The question as stated in title, why?

Inquiry: When introducing de Broglie waves, the author of my modern physics book first makes the analogy of a wave propagating on a string. Naturally the displacement at any time is given by y=Acos2\pift, where A is amplitude of the vibrations and f is the frequency. Then he argues that a more...

Am I correct in thinking that the quantum mechanical de broglie wavelength explains relativity's contraction of matter? because lambda = h/p, as the velocity of say a proton increases, the momentum also increases, and the wavelength should get smaller because lim p-->infinity of h/p = 0. At very...

De broglie wavelength of fast moving particle--help please! Homework Statement A particle moving with kinetic energy equal to its rest energy has a de Broglie wavelength of 1.7898 *10^-16 m. If the kinetic energy doubles, what is the new de Broglie wavelength? Homework Equations...

Homework Statement A certain crystal has a set of planes 0.33 nm apart. A beam of neutrons strikes the crystal at normal incidence and the first maximum of the diffraction pattern occurs at ∅= 38°. What is the de Broglie wavelength of the neutrons? Homework Equations nλ = Dsin∅ where D...

Hello, In the book physical chemistry (P. Atkins & Julio de Paula, 2009, 5 ED) the authors derive a justification of the Schrödinger equation. 1.) \frac{-\hbar^{2}}{2m} \frac{d^{2}\psi}{dx^{2}}+V(x)\psi=E \psi The derivation goes as follows: Derivation: We can justify the form of...

The atoms in a gas can be treated as classical particles if their de Broglie wavelength is much smaller than the average separation between the particles. Compare the average de Broglie wavelength and the average separation between the atoms in a container of monatomic helium gas at 1.00 atm...

Homework Statement In quantum mechanics the de Broglie wavelength of an object depends on its momentum according to λ=h/p where h is Planck's constant. Protons of charge e and mass m are accelerated from rest through a potential V. What is their de Broglie wavelength? A) 2h/\sqrt{}meV...

As we know that the properties of nanoscale material are quite diffrent from the bulk's. But what's the threshold of the size, or what the upper limmit where significant difference can be observed? The De Broglie wavelength or the Fermi wavelength of the electron in material? How to understand that?

Doesn't the Bohr model use standing waves as a reference? Before De Broglie's hypothesis, how did Bohr manage to assume that electrons are waves?

Homework Statement What is the De Broglie wavelength of an electron with KE= 8.5 eV? Homework Equations λ=h/p KE=0.5mv2 p=mv The Attempt at a Solution I converted 8.5 eV into joules: 8/5 eV × 1.602e-19 J = 1.3617e-18 Then used it for KE to solve for v: I got 1729006.11...

Homework Statement http://img580.imageshack.us/img580/7492/50177994.jpg The Attempt at a Solution I first attempt part (a) since both parts are similar: (a) I need to know "v" in order to use the following equation to find the de Broglie wavelength: \lambda = \frac{h}{p}...

I'm having trouble understanding some things about the De Broglie relation, λ=h/p 1. A massive system, such as an atom, is a composite of several particles (protons/neutrons, electrons), each of which is a matter wave with its own wavelength, according to De Broglie relation. But the atom...

Dear Physics Forum, I think I am confused in applying the correspondence principle in QM, using the particle in a box and de Broglie wavelength calculations for massive (macroscopic) objects. Why is the calculated energy of a massive object so small in the particle in a box E = h2/8mL2...

We can calculate a de Broglie wavelength for a particle with momentum p. My question is does this apply to the lateral size of the particle? Perpendicular to the motion the momentum is zero. What can we say about the size of the particle in the perpendicular direction?

Homework Statement The Attempt at a Solution I don't see how they got sqrt(1.5/E) I tried it like this Not the right answer.

I went back to my old introductory books on Quantum Mechanics and noticed the derivation of the de Broglie relation. Therefore I have now this question: How much does the de Broglie relation (p = hb k) depend on Special relativity? Would the dependence be strong enough that one may...

While deriving De-Broglie wavelength we equate mc^2 to hf and then for electron we change c to v but as far I know mc^2 is rest energy then how could c be converted into v for electron.Shouldnt it have the same rest energy?

I'm reviewing for one of my final exam and I can't seem to figure out this problem: Find the Debroglie wavelength of an electron with a KE of 40 ev. I got an answer of 3.9 x 10^-10 m. I keep getting it wrong and I'm not sure what to do. Thanks in advance!

My book does not explain this and i can't rly find a simple explanation for this on google and my professor basically dodged my question: So the de Broglie wavelength formula basically says that matter creates waves with wavelength h/p, where p is the matter's momentum. However, when the...

Hello everybody at physicsforums.com! This is my very first topic in here, although I visit the forum for some time. I'm from Brazil and as english is not my mother language, i ask you not to be so harsh with my probables grammar mistakes XD. Well, so let's get to business. I have...

According to Broigle, λ=h/p where p=momentum, h=planck constant, and λ=wavelength But that means, if λ increases, then p will increase p=mv and so v will increase along with the wavelength But what if the v is that of light,i.e, c?

Does de Broglie wave length apply to composite particles? For example a very low momentum neutron does it have a very large wave length? Or do we think in terms of the three quarks that make up the neutron? The three quarks do not have low momentum they are banging back and forth inside the...

i want to know the practical application of De Broglie wavelength in the life !

Homework Statement (a) Find the kinetic energy of an electron whose de Broglie wavelength is equal to 0.63 Å, a typical atomic size. Ke = 379 eV (b) Repeat part (a) for an electron with a wavelength equal to 1.7 x 10-15 m, a typical nuclear size. Ke = _____eV Homework Equations...

Homework Statement In the Bohr model of the hydrogen atom, if the electron is in the second orbit with a radius of 2.12 Å. What is the de Broglie wavelength of the electron? Homework Equations λ = 4h^2ε/me^2 The Attempt at a Solution I found this equation hunting around online and...

Find the kinetic energy of the following particles that each have a de Broglie wavelength of 0.50 nm.? (a) photons ____eV = 2480eV (b) electrons ____eV (c) neutrons ____eV (d) α particles ____eV i know E= hc/wavelength which = a and after that I am stuck i know that the wavelength =...

Hello there, If an object has a mass of 1 in arbitary units, and it's velocity is zero relative to you, what is the de Broglie wavelength? Shouldn't p be zero in this case? Or am I missing something related to intrinsic energy and momentum? Thank you very much.

Homework Statement Find the de Broglie wavelength for an electron with v=0.001c. Find the angular width of the central bright fringe in a double slit experiment, with the separation of the two slits d=50nm. Homework Equations wavelength = h/mv d sin(theta)=n*wavelength The...

If a photon hits electron which is at rest. scatters electron. Some one pleas show formula that relates compton wavelength and de broglie wavelength of electron

Alright, as this wikipedia article states that, "A wave is a disturbance that travels through space and time, usually accompanied by the transfer of energy. Waves travel and the wave motion transfers energy from one point to another, often with no permanent displacement of the particles of the...

Photons are blue-shifted as they accelerate in free-fall toward the earth. When an electron or positron is conceptualized as a wave using de Broglie's equation, are the de Broglie wavelengths of the electron or positron shortened (blue-shifted) as they accelerate toward the Earth in free-fall...

Why is the de Broglie wavelength sometimes larger than the particle it describes? Thanks, Jake

I've posted a similar question here before, but to no avail. My question is, what is the cause for the propagation of a matter wave? In the same sense that oscillating electric and magnetic fields carry light across space (for lack of a better explanation), and every wave propagates through a...

In the same sense that sound waves propagate through air, water waves through water, light through spacetime, what medium does the de broglie wave propagate through? Also, how could one detect such a disturbance in this medium without measuring the particle itself? (i.e. you can see the wake of...

Question-A certain crystal has a set of planes spaced 0.376 nm apart. A beam of neutrons strikes the crystal at normal incidence and the first maximum of the diffraction pattern occurs at a scattering angle (i.e angle between incoming neutrons and reflected beam) of 41.4 degrees. What is the de...

i was working on atomic structure and i stuck here. how can a wave be associated to any material? is it related to wavelength of colur it emits or is it the wavelength of vibrations after it has been stuck by something? what is it??

So, I've come across a new page in my revision guide in the Quantum Phenomena section, labelled "de Broglie wavelength". My old enemy. Now, I understand the theory behind wave-particle duality, I just don't understand this chunk of de Broglie and his equation. Here it reads "The de...

Just a very quick question: in my notes I have the velocity of a DeBroglie wave is given by: \nu\lambda=2\pi\nu\frac{\lambda}{2\pi}=\frac{\omega}{k}=\frac{E}{p}=\frac{c^{2}}{v} I can't figure out how he want from E/p=c^2/v. I think the assumption is made that E is approximately equal...

I have taken down in my notes that for massless particles the formula by DeBrogle becomes E = pc, where p is momentum and c is the speed of light. But what I don't understand is how you can calculate momentum without mass? I thought momentum was mass times velocity? The specific example I...

An electron around a hydrogen-atom, with radius r and length of circle a whole number, n, times wavelenght. This implies that 2*3,14*r=n*(wavelenght) I have read someplace that if you substitute the wavelenght with h/p, you can find the kinetic energy of an electron, which is the same as...

This question appeared in my exam . Q. A bullet of mass 41g travels at 960m/s. what wavelength can we associate with it? why does the wave nature of the bullet not reveal itself though diffraction effects? Ans.. i find de broglie wave length by formula lamda = h/mc but didnt...

Homework Statement To "obeserve" small objects,one measures the diffraction of the particles whose de Broglie wavelength is approximately equal to the object's size. Find the kinetic energy(in electron volts) required by the electrons to resolve c) a nucleus of size 10fm. Homework...

I have a few questions: 1. 'small smoke particles in air are seen under a low magnification microscope to move randomly at a speed of 0.10mm/s. The speed of sound in air is 330m/s. Estimate the mass of the smoke particles. I cannot make the link between speed of particle and speed of sound -...

Homework Statement An electron in the first Bohr orbit of a hydrogen atom (a_0=5.3*10^-11m) has a KE of 13.6 eV. Express the de Broglie wavelength for this electron in multiples of the atomic circumference. Homework Equations lambda=h/p =h/(sqrt(2mqV) The Attempt at a...

Homework Statement What is the de Broglie wavelength of a neutron traveling with a momentum equal to 300 \frac{\text{MeV}}{\text{c}}? Homework Equations \lambda = \frac{h}{p} The Attempt at a Solution p = \frac{300 \cdot \left( \left(1\times10^6 \right) \times...

What relationship did de Broglie postulate between the momentum of a particle and the wavelength of the corresponding matter wave? Explain briefly how a beam of electrons may be used to investigate the atomic structure of the surface of a metallic substance. Estimate the potential...

I've been studying quantum physics for a little over a semester now and I'm having trouble wrapping my head around the physical significance of matter waves. The derivation also confuses me because it states the momentum of particle with mass as mc, which is only true for a massless photon. I...

Just a random thought: is it not possible for a person to move slow enough to have an observable de Broglie wavelength? For example a person moving at around 10^-30 m/s should have a wave nature that is very observable.

Homework Statement By estimating the De Broglie wavelength and the inter-particle spacing, find whether the following systems of particles are degenerate: (i) a gas of neutrons in a neutron star with mass density 10^17 kg/m^3 at the temperature of 10^8K (ii)a gas of oxygen molecules at...