De broglie Definition and 266 Threads

Homework Statement Show that the de Broglie wavelength of a particle of mass m and kinetic energy KE is given by \lambda = \frac{hc}{\sqrt{KE(KE + 2mc^2)}} Homework Equations The Attempt at a Solution I know: KE = {\gamma}mc^2 - mc^2 = pc - mc^2 But from here I am...

E=mc^2 and E=hf. In Special Relativity, how can y=h/p be derived from E=hf?

Homework Statement In his presentation of the de Broglie wavelength and the wave/particle duality, my quantum prof. has an exercise: "Find the de Broglie wavelength of a molecular vibration. Do quantum or classical laws apply?" Homework Equations wavelength = h/(momentum) ...

I am trying to help my son in his year 12 physics. I know very little of this can someone please assist. find in eV (electron volts) the energy of a proton with a de broglie wavelength of 40 pm (picometres) What would the correct formula be ? A good chance for me to learn as well ;)...

Hello, I've always wondered about the "relativity" of the De Broglie wavelength. The wavelength depends on the momentum of the specific thing we are observing, thus on different frames of reference(F.O.R from now on :P) we might get different answers. I have been looking through the web to...

Homework Statement Calculate the de Broglie wavelength of an oxygen molecule (molecular mass 32)in air at room temperture. Homework Equations P = h/ \lambda P= mv E= hv = 1/2mv^{2} = P^{2}/(2m)The Attempt at a Solution hv = 1/2mv^{2} h = 1/2mv If v = P/m then h = mp/2m so p= 2h This...

I can work out the wavelengths fine, but I am unsure of the answer to the second part, any help would be much appreciated

I am interested to know why in any description of electron diffraction apparatus they seem to suggest that the electrons need accelerating up to 5kV (or at least several kV) to show the electron diffraction rings, this seems to give a de Broglie wavelength of around 1.2 x 10^-11m whereas the...

Homework Statement What is the de Broglie wavelength of a neutron whose kinetic energy is equal to the average kinetic energy of a gas of neutrons at temperature T = 17 K? Homework Equations lambda = h/p = h/mv. The Attempt at a Solution Well first I tried taking the h =...

Homework Statement Earth has the mass 6 · 10^24 kg and the orbit radius r = 1.5 · 10^11 m. (a) Compute its de Broglie wavelength. (b) Apply de Broglie quantization condition as in the case of the Hydrogen atom and compute the quantum number n for the orbit of Earth. (c) What is the...

Homework Statement Find the de Broglie wavelength of an 8 MeV proton. Homework Equations y = h/p where y is the wavelength p = mv K = Eo/sqrt(1-v^2/c^2) where Eo is the rest mass and K is the kinetic energy The Attempt at a Solution I make the assumption that "an 8 MeV proton"...

Hi, I am very new to Quantum Physics. In every wave, something should oscillate. In water waves, water molecules oscillate. In electromagnetic waves, electric and magnetic fields oscillate. So what oscillates for a de broglie wave? Take a neutron as an example.

Hi there, Is it possible if an object were to hypothetically gain enough momentum such that its de Broglie wavelength is equivalent to, say, some light in the visible spectrum, that the object would emit light? Thanks!

According to the de Broglie hypothesis, which of the following statements is applicable to the wavelength of a moving particle?

Hi, Could someone please crunch for me the de Broglie wavelenght (\lambda), frequency (f) and energy (E) of Earth at perihelion (30300m/s) and at aphelion (29300m/s) and mean (29800m/s) Here are the numbers and formulas: \lambda=h/p , f=E/h , p=m*v (momentum=mass*velocity) h - Planck's...

Homework Statement What is the de Broglie wavelength of a 10 microKelvin Rb atom? A 5000K electron? Homework Equations \lambda=\frac{h}{p} V=\sqrt{\frac{3KT}{m}} The Attempt at a Solution I used the velocity equation to find the velocity relating to temperature and mass. Then, as...

OK so you get to the matter wave equation 'lambda = h / p' using E=cp - which describes the energy for massless particles. I can understand this holding for when cp>>mc^2 , but not for when the mc^2 is comparible. Any help?

Wavelength of an electron Homework Statement -Electron has 3.00 MeV (or 4.8*10^-13 Joules) -it's relativistic -finding λ. Homework Equations h=6.63*10^-34 λ=h/p (obviously) And I'm not sure if they're needed, but the relativistic eq's are: KE = mc^2/sqrt(1-(v/c)^2)...

Homework Statement an electron is moving at 2.5 x 105m/s. Find the electron's De Broglie Wavelength. Homework Equations De Broglie relates wavelength of electron waves to momentum of the electron by lambda = h/p where h is Planck's constant. The Attempt at a Solution given the...

Homework Statement Estimate the wavelength of a 30 keV electron. Homework Equations p = h/λ E = hf The Attempt at a Solution The electron has 30 keV of mass-energy. As it is acting as a particle-wave, E = hf, so f = E/h = 30,000x1.6x10^-19/6.3X10^-34 = 7.619x10^18 Hz Now, v =...

Homework Statement What was the significance of the de Broglie equation? Homework Equations p = h/λ p = mv The Attempt at a Solution It says that not only do waves act as particles, transferring energy and momentum to matter only at localised points, but moving particles (e.g...

Hi, just some quantum physics questions. I've given them all a good go, the first two just require checking, but the rest I'm rather stuck on. They're the last questions in about 20 other ones, and my head now hurts. :( Any hints are very much appreciated! Homework Statement I firstly...

Homework Statement The potential-energy function U(x) has the constant value U_0 in the interval 0 < x < L and is zero outside this interval. An electron is moving past this square barrier, but the energy of the electron is greater than the barrier height. If E= 6 U_0, what is the ratio...

Homework Statement In one of the classes, a recent experiment showing the interference of C60 molecules using a double slit apparatus was discussed. (a) If the average velocity of the C60 molecules is v= 200 m/s, calculate the De Broglie wavelength for a C60 molecule Homework Equations...

Homework Statement What is the de Broglie wavelength of this electron? Given is 500 eV Homework Equations KE= 1/2 mv^2 1 eV=1.602x19^-19 J The Attempt at a Solution I converted the 500 eV to 8.01x10^-17 via the given conversion. Now I'm stuck.

In Classical Mechanics the derivative of Kinetic energy with respect to velocity is momentum, so I was wondering if this is valid: In this L is lambda or wavelength and h is Planck's Constant. E=hf, therefore E=h(v/L) This means that dE/dv=h/L.(h and L are constants and the derivative of...

Homework Statement De Broglie wavelength What is the De Broglie wavelength of the 1.0-TeV (1TeV=1012eV) protons (mpc2=938.3MeV) accelerated at the Fermilab Tevatron accelerator? These high-energy protons are needed to probe elementary particles [Hint: You need to use relativistic formula, but...

If, in the expression for the de Broglie wavelength, we let m -> infinity, do we get the classical result for matter? de Broglie wavelength = h/mv so as m goes to infinity the de Broglie wavelength goes to 0. So does this mean that particles with larger mass don't display wavelike...

I saw a proof in a book for the de broglie equation which I thought was wrong. if l = lambda, so wavelength and then all other notation is standard they said: E=mc^2 E=hf therefore, mc^2=hf but for a photon, c=v so: mv^2=hf but mv=P so: Pv=hf and v=fl so: Pfl=hf...

Homework Statement Use the dispersion relation to find the group velocity v_group and phase velocity v_phase. Homework Equations omega(k) = [(hbar)k^2]/2m The Attempt at a Solution v_group = domega(k)/dk = [hbar]k/m = h/m lambda = p/m = v This isn't right. v_phase = omega...

This isn't a homework question, but something which has been bugging me. I can't figure it out. Maybe it's late, but it's probably a very stupid question If light shines onto a denser medium, the light slows down in this medium right? If the light slows down, then by the wave equation, v =...

Homework Statement I am trying to describe the limit for the minimum radius of a star to first year university level students in order to describe the reason for the size of the Sun. I'm a bit confused by the critical density of the material in the star's core and how we know that the main...

If a ball with mass m_1 moving at speed v strikes another ball of mass m_2 that is initially at rest in a head-on elastic collision, the speeds of the two balls after the collision are v_1 = v (\frac {m_1 - m_2}{m_1 + m_2}), v_2 = v (\frac {2 m_1}{m_1 + m_2}) respectively. If a wave...

Homework Statement The question is from Advanced Physics by Adams and Allday, section 8 Practice Exam Questions, question 30. Estimate the de Broglie wavelength of an electron that has been emitted thermionically in a vacuum from a filament and then accelerated through a p.d. of 30.0 kV...

Homework Statement Question 1) Calculate the de Broglie wavelength of a neutron (mn = 1.67493×10-27 kg) moving at one fiftieth of the speed of light (c/50). Question 2) Calculate the velocity of an electron (me = 9.10939×10-31 kg) having a de Broglie wavelength of 225.7 pm...

As a beginner in quantum mechanics I have already lost my way on de Broglie waves. A free particle is a linear superposition of de Broglie waves and satisfies the Shroedinger equation with zero potential. Do the component de Broglies waves have physical meaning or are they mathematical...

what does the momentum in de broglie wavelength signify? i mean how do u defien it...we can define the expectation in momentum but how do we define momentum for "quantum mechanincal" particles

The de broglie wavelength is h/p, where p is momentum, and hence mv, so wavelenght = h/ (mv). The mass is on the denominator, so a massive object, like a baseball, will have a small wavelength, beyond detection and we can ignore it. OK, so does the mass have to be moving to have a de broglie...

Homework Statement A 220lb fullback runs the 40-yd dash at a speed of 19.6 ± 0.1 mi/h. What is he de Broglie wavelength (in meters)? Homework Equations de Broglie Wavelength: λ=h/(mu), where λ=wavelenght, h=6.626 x 10^(-34) kgm^2)/s, m=mass (kg), and u= speed The Attempt at a...

Homework Statement Calculate the de broglie wavelength (DBW) of an electron with kinetic energy 60 GeV. What percentage of an atom's diameter can it penetrate? Homework Equations DBW = h/p p=mv The Attempt at a Solution Basically I have an electron traveling at the...

I had a go at 2 Q's and wanted to make sure I'm doing this right. so here's the first one, and maybe if i went wrong with it I was going to redo the 2nd Q on my own. \lambda = h/p = h/mv (\sqrt{1-((v^2)/(c^2))}) so, an Alpha Particle traveling @ 2x106m/s (mass = 6.645x10-27 kg)...

Homework Statement Atoms are on the order of one Angstrom (A) or 10-10m in size while the diameter of the nucleus is approximately one hundred thousand times smaller. Let's pretend we have a "classical" atom where both the atom and its nucleus have a defined position and size. (This it...

Homework Statement An electron has a de Broglie wavelength of λ = 6.4e-10m. What is its speed? What voltage was needed to accelerate to this speed? Homework Equations v=h/mλ KE = 1/2mv^2 The Attempt at a Solution I already determined that the speed is 1.136e6 m/s. Finding the...

Does anyone know how to plot the electron standing wave around a nucleus in Cartesian coordinates? I have tried adding a sine/cosine function to the circle equation but the image does not look correct and I also don’t know how to increase the wave count when n > 1.

What is the relationship between the "matter waves" described by de Broglie, the probability amplitude function and Schrödinger's wave equation? I've read the following: "The wavelengths postulated by de Broglie to be associated with the motions of particles are in reality the wavelengths...

The wave-frequency relationship is as follows: f = v / \lambda Therefore: v = \lambda * f The de Broglie relations are as follows: \lambda = h / p f = E / h Using some basic algebra: v = (h / p) * (E / h) v = E / p v = \gammamc^{}2 / \gammamv v = c^{}2 / v Now...

Well I asked three people and they all gave me three different answers... One say to pronounce it the Broglie as how you would say "broil" other one said to say Broglie as "bro-glee" last one said...Broglie as "bro-lee"

What is the amplitude of the wave produced by an object of resting mass m0 when it is going a velocity v? I haven't come across any information on the amplitude of de Broglie waves, and thus I assume that the amplitude of the wave is proportional to the Lorentz factor, m0/sqrt(1+v^2/c^2). Is...

Relativistic or Classical?? Calculation of De Broglie Wavelength Hi there, Okay, the question is: Calculate the De Broglie Wavelength of a 10 MeV proton and a 1 MeV electron. How does one know whether to use relativistic or classical means? Relativistic => Kinetic / Rest mass >/ = 10%...

How do you calcuate at what energy do a photon and an electron have the same de broglie wavelength?