Louis Victor Pierre Raymond, 7th Duc de Broglie (, also US: , French: [də bʁɔj] or [də bʁœj] (listen); 15 August 1892 – 19 March 1987) was a French physicist and aristocrat who made groundbreaking contributions to quantum theory. In his 1924 PhD thesis, he postulated the wave nature of electrons and suggested that all matter has wave properties. This concept is known as the de Broglie hypothesis, an example of wave–particle duality, and forms a central part of the theory of quantum mechanics.
De Broglie won the Nobel Prize for Physics in 1929, after the wave-like behaviour of matter was first experimentally demonstrated in 1927.
The 1925 pilot-wave model, and the wave-like behaviour of particles discovered by de Broglie was used by Erwin Schrödinger in his formulation of wave mechanics. The pilot-wave model and interpretation was then abandoned, in favor of the quantum formalism, until 1952 when it was rediscovered and enhanced by David Bohm.Louis de Broglie was the sixteenth member elected to occupy seat 1 of the Académie française in 1944, and served as Perpetual Secretary of the French Academy of Sciences. De Broglie became the first high-level scientist to call for establishment of a multi-national laboratory, a proposal that led to the establishment of the European Organization for Nuclear Research (CERN).
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...
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...
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 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
In an electrom microscope we wish to study paprticles of diameter about 0.10 µm (about 1000 times the size of a single atom).
What should be the de Broglie wavelength of the electrons?
Through what voltage should the electrons be accelerated to have that de Broglie...
Homework Statement
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 atoms in a container of (monoatomic) helium...
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!
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...
Homework Statement
If the be Broglie wavelength associated to the first orbit of the electron inside the atom of hydrogen is 62.4 nm, what is the wavelength associated to the fourth orbit?
1. 62.4 nm
2. 124.8 nm
3. 312 nm
4. 249.6 nm
Homework Equations
# of...
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...