The electron is a subatomic particle, symbol e− or β−, whose electric charge is negative one elementary charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. Being fermions, no two electrons can occupy the same quantum state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: they can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
Electrons play an essential role in numerous physical phenomena, such as electricity, magnetism, chemistry and thermal conductivity, and they also participate in gravitational, electromagnetic and weak interactions. Since an electron has charge, it has a surrounding electric field, and if that electron is moving relative to an observer, said observer will observe it to generate a magnetic field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law. Electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields. Special telescopes can detect electron plasma in outer space. Electrons are involved in many applications such as tribology or frictional charging, electrolysis, electrochemistry, battery technologies, electronics, welding, cathode ray tubes, photoelectricity, photovoltaic solar panels, electron microscopes, radiation therapy, lasers, gaseous ionization detectors and particle accelerators.
Interactions involving electrons with other subatomic particles are of interest in fields such as chemistry and nuclear physics. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms. Ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the main cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of an indivisible quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge 'electron' in 1891, and J. J. Thomson and his team of British physicists identified it as a particle in 1897 during the cathode ray tube experiment. Electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of radioactive isotopes and in high-energy collisions, for instance when cosmic rays enter the atmosphere. The antiparticle of the electron is called the positron; it is identical to the electron except that it carries electrical charge of the opposite sign. When an electron collides with a positron, both particles can be annihilated, producing gamma ray photons.
Hi, I'm having trouble understanding angular moment of the one electron hydrogen atom.
Solving Schrodinger equation on a referece system (say S) I get the energy eigenstates. They depend on three quantum numbers, n, l, m
\frac{-ħ}{2 m}\nabla^{2} \Psi - \frac{e^{2}}{4 \pi \epsilon r} \Psi =...
This is an elementary question on visualizing the interaction of an electron with the surrounding EM field in QFT. I believe in QFT the electron is viewed as an excitation of the Electron matter field with an associated coupling constant between the electron field and EM field (say q) - q...
If I'm scattering electrons off of an atomic nucleus, can I infer any information about the duration of time the electron was accelerating by looking at the wavelength of the emitted bremsstrahlung radiation? I am wondering if it would be possible to derive a time interval between electron...
I am trying to find the thermal speed of electron at room temperature.
kT = (1/2)mv^2
which gives v=√((2kT)/m)
but answer says it should be √((kT)/m)
Where did that 2 go?
Hey!
Let's say we have an electron and proton colliding head-on.
We will have ##|p| \sim E##
Where ##p_1=(E_1, \vec{p_1})## &##p_2=(E_2, \vec{p_2})##
If we want the available energy. We can calculate ##\sqrt{s} = \sqrt{(p_1 + p_2)^2}##
We get $$s= p_1^2 + p_2^2 + 2p_1p_2 = m_e^2 + m_p^2 +...
Homework Statement
One way to establish which transitions are forbidden is to compute the expectation value of the electron’s position vector r using wave functions for both the initial and final states in the transition. That is, compute ∫ΨfrΨidτ where τ represents an integral over all space...
I'm reposting this thread with some editing suggested by fresh_42:
1. Homework Statement
Calculate the mass, velocity and the de Broglie wavelength of an electron and an alpha particle, given the kinetic energy K = 2MeV
Homework EquationsThe Attempt at a Solution
please find attached![/B]...
Hi,
As far as I understand spin orbit coupling is the interaction between proton of atom and electron. Proton's motion(from the frame of electron) around electron creates magnetic field. Hence electron experiences magnetic field. Does this magnetic field produces a Zeeman effect which cause...
I know that total magnetic moment of an electron (I am not sure if it is magnetic moment of electron or atom, please clarify this) is sum of magnetic moment caused by orbital motion and spin angular momentum.
So,
Total magnetic moment = Orbital magnetic moment + spin magnetic moment
Do I have...
Suppose you have a pair of electrons in the same quantum state, and are thus spin entangled, and they absorb a pair of photons and release them at the same time. How would this affect the photons? Would the photons be entangled? Would it affect the photon spin, and if so, how would it affect the...
Hi all, I am having trouble understanding the some ideas presented in some notes I've been reading, help is greatly appreciated!
I've uploaded screenshots of the material I'm referring to below, the last two images are what I'm mainly referencing, and the first few are to provide context...
Previously I posted a problem concerning Electron-neutrino scattering, but as I couldn't describe the problem clearly, so I am trying to post the problem using latex codes to present it in the correct way.
For a couple of months, I am trying to calculate the invariant amplitude of the Neutrino...
If the mass of the electron has been changing during the evolution of the universe, then the orbits of the electrons would also change, which will shift the light spectrum of each atom.
Could this explain red shift of far galaxies, and the shift is not because the universe is expanding?
Henry
For a couple of months, I am trying to calculate the invariant amplitude of the Neutrino electron scattering in the standard model (SM) approach where I am not considering any kind of approximation and using the SM propagator for W Boson and Z Boson.
I tried to do as following,
find out the...
In Abraham Pais book (which was first published in 1982), he states the following:
"Quantum field theory has taught us that particles nevertheless have structure, arising from quantum fluctuations. Recently, unified field theories have taught us that the mass of the electron is certainly not...
Homework Statement
For silicon at T=300K with donor density ND=2×109cm−3, acceptor density NA=0 and ni=8.2×109cm−3, calculate the equilibrium electron and hole concentration
Homework Equations
n_0=\frac{N_D-N_A}{2}+\sqrt{\frac{N_D-N_A}{2}^2+n_i^2}
p_o=\frac{n_i^2}{n_0}
The Attempt at a...
Homework Statement
What is the radius of the orbit of an electron traveling at 9.0 x 10^6 m/s around a zinc nucleus which contains 30 protons?
Homework Equations
I don't know if this problem can be solved quantum mechanically, all I can think of doing is solving it classically, using Coulomb's...
Is a photon fully absorbed by a electron in metal?
Ejected electron is a free electron or bonded one?
Is it possible to have a zero work function? If not why?
I want to study about this detaily ,can you prefer some reference papers?
Homework Statement
An electron in a hydrogen atom falling from an excited state to the ground state has the same wavelength than an electron moving at a speed of 7821 ms^-1. From which excited state did the electron fall from?
Homework Equations
I used the kinetic energy equation:
K = (m...
I couldn't fit the whole question, it should say
"How close does an electron have to get to a proton to be attracted to it"
And I know it can depend on the speed and direction they are traveling. Can we just pretend they are stationary for this answer please.
By attracted I mean the electron...
Hi
I am surprised to know why only one photon in photoelectric effect ejects one electron only. What if a high energy photon (not necessarily x-ray or gamma ray, which may cause Compton effect or pair production)hits the metal, say it has energy double or triple of that of the work function? Why...
Homework Statement
A photon of wavelength 300nm is emitted from an atom when an electron makes a transition from an energy state of -4 eV to a state of -8 eV. IF the initial state had been at enerygy of -6 eV, the wavelength of the photon emitted in a transition to -8eV is..??
Homework...
pg. 243 Falconer, I. (1987) Corpuscles, Electrons and Cathode Rays: J.J. Thomson and the Discovery of the Electron. The British Journal for the History of Science (BJHS, 1987,20,241-276). "One of their most important properties is that they are deflected by a magnetic field. This provided strong...
Homework Statement
An electron and a proton are each placed at rest in an electric field of 687 N/C. What is the velocity of the electron 56.5 ns after being released? Consider the direction parallel to the field to be positive. The fundamental charge is 1.602×10−19 C, the mass of a proton is...
Is it reasonable to assume that the energy of the electrons used to power a diode, equals the energy of the photons emitted from the diode? If so, why?
In my study of Quantum physics i have arrived at the natural shielding caused by photon to electron/anti-electron pair fluctuations.The shielding reduces as you get closer the electron which naturally leads me to the question.What actually is the charge on an electron?
Homework Statement
An Electron with an initial speed of 500,000m/s is brought to rest by an electric field
a)did the electron move into a region of higher or lower potential? I
b) what was the potential difference that stopped the electron?
Homework Equations
ΔV=ΔU/q
ΔU=-W
The Attempt at a...
I have am currently reading Radiation Detection and Measurement, by Gleen F.Knoll, and in chapter 10 page 309.
And have come across something that is causing a bit of confusion, for context the chapter is on gamma ray spectroscopy.
So in the text it say's 'Thus the effect of photoelectric...
If an electron were to be spontaneously created at a point somewhere in space, would the electron's field expand outwardly at the speed of light, regardless of frame, just like how a flash of light would expand outward at the speed of light, regardless of frame?
Homework Statement
Hello PF!
Got a two-part question involving calculating the electric force on a electron when placed in an electric field of 0.75N/C to the right, and the acceleration of said electron. Our values are E=0.75N/C, q=-1.6e^-19, m=9.1e^-31 (charge and mass of electron)...
In practice, ESR/EPR seems to concern only unpaired electrons in the outer layers of organic radicals or complexes. But what about the free electrons of metals? Does it also give rise to a signal? I can't find any information on the web.
Thanks
Do you know when the energy content of electrons was actually measured as .511 MeV? was the first measurement true to current value? and, most of all, how was/is it measured with precision?
Homework Statement
Is there a minimum value for the total energy of the electron (in this analysis)?
The previous parts:
Use Larmor formula to find ##\frac{|\Delta E|}{K}##, where ##|\Delta E|## is the energy lost per revolution.
the result is ##\frac{8\pi v^3}{3c^3}##.
##\frac{v(r)}{c}## was...
Homework Statement
Find an expression for the time it takes for an electron to spiral in from an initial radius ##r_i## to a final radius ##r_f##. Write your answer in terms of ##r_i##, ##r_f##, ##m_e##, e, and c.
Homework Equations
Larmor Formula:
$$\frac{dE}{dt} =...
Homework Statement
A point charge of -1.0 µC is located at the origin. A second point charge of 16 µC is at x = 1 m, y = 0.5 m. Find the x and y coordinates of the position at which an electron would be in equilibrium.
Homework Equations
F=k((q1q2)/r^2)
The Attempt at a Solution
I have gotten...
Why is the electric potential of an electron in a capacitor measured from the negative plate and not the positive plate here?
This is from Liboff Introductory quantum mechanics 1st(current is 4th) edition:
I don't understand why the distance z is measured from the bottom plate if the...
Hello! I found this problem where we are asked what happens to the energy of the outgoing photon in a Compton interaction, if the mass of the electron goes to zero and what is the physical intuition of it. So the formula is this: $$\lambda - \lambda_0 = \frac{h}{m_0 c}(1-cos \theta)$$ So when...
When do we use the Boltzmann equation for density in a Fermi plasma?
n in [cm-3]
and when do we use the ρ=m/V, ρ in [Kg/m3 ]
(this is not an example, I just added the equations to make my question more understandable)
Is the ideal gas only when we have electron and ions? Is the Boltzmann...
Homework Statement
Cylinder electron gas with density of ne= 1010 and radius or r=1cm is inside magnetic field of B=104 Gauss.
If we change the electron gas with
(i) muon gas
(ii) proton gas
does the Drift Velocity change?
Homework Equations
[/B]
Boltzmann equation of density...
Homework Statement
In the figure, an electron of mass m, charge − e, and low (negligible) speed enters the region between two plates of potential difference V and plate separation d, initially headed directly toward the top plate. A uniform magnetic field of magnitude B is normal to the plane...
Why all particles of same type identical? All electrons are identical to each other, all protons are identical..etc. It is as if they are copy pasted from each other!
For me this is one of the biggest mysteries ever, why we don't detect more massive or less massive electrons?
Is it related...
what are the dimensions of the double slits in comparison to the electron?
what keeps the electron from decaying outside the environment of an atom long enough to run the experiment?
how are the electrons detected before and after the slits?