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.
In a standard kitchen-microwave magnetron, like all magnetrons, a cloud of electrons forms which whizzes around and generates GHz electric currents in an outer ring electrode.
For such a standard kitchen appliance, 800W made with ferrite magnets, what is the typical volume and density of the...
Hi, in the lecture notes my professor gave us, it is stated that, due to Kramers theorem, the energy in a band must satisfy this condition:
$$E(-k) = E(k)$$
But, judging from actual pictures of band structures I don't find this condition to be true. Here's a (random) picture
I guess it looks...
https://ecee.colorado.edu/~bart/book/effmass.htm#short
Looks like the effective mass for holes in Si can either be 0.57 or 0.81, according to the link above.
Is there a temperature regime where one effective mass should be used instead of the other?
Is anyone able to explain in layman's terms...
I know that we use quantum mechanic and wave function to calculate probability of finding electrons but is there anything valid about bohr model that we still use it?
So I can understand how to find out velocity of electron moving between these 2 plates, by using:
How am I supposed to find the 'minimum' velocity though?
According to the semiclassical approximation, in response to a constant electric field I would get a periodic motion of the electron, like this:
The sinusoidal type function is the velocity, while the function that goes to infinity is the effective mass. Thus I was wondering, since ##v## also...
In five years also experiment KATRIN will give either the upper bound of electron neutrino mass (0,2 eV) or even the mass of the electron neutrino. https://www.katrin.kit.edu/
My question is, what we can expect from the astronomical and non-astronomical measurements to improve these data? I...
Hi,
Can anyone explain the concept of K.E. and P.E. in a semiconductor?
Why Ec (lower level of Conduction Band) is considered as P.E. ? and why the Difference between the higher energy state and Ec is Kinetic energy ?
I understand it if I look at the Bohr model but I am not clear how to look at...
When electrons get excited they are unstable, therefore they want to go back to ground state. One way they do so is by creating photons (e.g. mirrors), but I've also read that they can create electricity (another electron?). Photoelectric is how it's called, right? If so, how can we choose...
Why is there a preferred z axis even though the potential energy function is perfectly spherical? Shouldn't the electron be around the nucleus in a spherically symmetrical way?
Summary: Born's rule for the QED electron violates causality.
[Since the thread where some of this material was presented was closed for further discussion, I summarize here the main content relevant for the above topic.]
The free QED electron can be described in terms of a non-local...
I’m not sure if this belongs in classic or quantum physics... but here it is...Is it possible to calculate the “voltage” between an electron and a proton in a ground state hydrogen atom?I know the ionization energy is 13.6 eV, so I assume it's safe to say the voltage is 13.6 volts at a certain...
I thought that a nearly parallel entry path would result in a helix of very small, but constant, radius. I would not expect the electrons to focus at a point, but continue along the infinite helix. What have I missed?
When I want to detect single electron(double-slits experiment), can I use usual photosensitive film(like Fuji-film, Kodak-film)? And, what specification I need?
You have probably heard this a thousand times before, but here goes...
We have an electron gun pointing at a double slit setup.
We switch it on and emit a single electron.
The electron approaches the double slit.
At each instant that electron has a definite position.
We do not consciously know...
In Peskin book they calculate the QED Vertex Function named Gamma which depend on two scalar functions called form factors F1(q^2), F2(q^2).
they are calculating F1(q^2) and they do not really finish calculating for what I understand. They are just showing the Infrared divergent is canceled by...
I'm having trouble understanding this process. The electron is absorbing the photon and has a changed orbital corresponding exactly to the photons energy. During the absorption the electron "jumps" energy levels, Is this process instantaneous? What are the equations that describe dynamics of...
We know that an electron and a positron will annihilate and emit gamma ray. But the electron and positron possesses initial kinetic energy meaning that it is difficult for them to really collide in each other. Just like Earth is not dropping into the Sun even with the gravitational pull. So I am...
Suppose there is a photon with momtum p=h/lambda moving in the positive x-direction. Suppose it collides with an electron at rest and is completely absorbed by the electron, and that after the collision, the electron moves to the right with the same momentum of the photon. This seems...
Because they evaporate, quantum micro black holes resemble unstable elementary particles: you can create them by smashing stable particles together, and then they will decay back into particles, as if it was all just another scattering process. Certainly in string theory, elementary particles...
i'am trying to find the ratio between the volume of the nucleus for the hydrogen atom to its electron , but when i try to use the previous equations it seems wrong as i'am getting a low number like if the electron is bigger .
i used the the classical electron radius as it was the only thing that...
For some work of mine i need the plasma resonance frequency for tin nanoparticle, i searched various research papers and found different efffective masses tin for different orbits. here i attached screen shot from W A Roger and S B Woods (Cyclotron effective masses in white tin). What value is...
I started with the first of the relevant equations, replacing the p with the operator -iħ∇ and expanding the squared term to yield:
H = (-ħ^2 / 2m)∇^2 + (iqħ/m)A·∇ + (q^2 / 2m)A^2 + qV
But since A = (1/2)B x r
(iqħ/m)A·∇ = (iqħ / 2m)(r x ∇)·B = -(q / 2m)L·B = -(qB_0 / 2m)L_z
and A^2 =...
It is well-known that the electron gas of volume V has an equation of state p=p(V) and thus has a bulk modulus $$B=-V(dp/dV)$$. Suppose the electron gas had no underlying lattice but was confined. Do phonons emit and absorb in such an electron gas at finite temperature?
The reason I ask is...
What forces are acting on electron in a circuit?
What is the source of such kind of forces?
Do electrons act on each other in electric current?
If i have an ordinary electric circuit with only one resistor, then if i raise resistance, the electric current goes down. As I understand it happens...
It is often said that in metals only the electrons having an energy within ##k_BT## of ##E_F## can contribute to a current. I do not understand where this ##k_BT## comes from. I know it enters the conductivity tensor because such a tensor can be written in terms of a surface integral over the...
Hello everyone, for quite some time I am struggling with the following question: If we consider the action for a single particle in Classical Electrodynamics
$$S[x(\tau),A(x)]=\int - m\ ds - \int d^4x\ A_{\mu}(x)j^{\mu}(x) -\frac{1}{4}\int d^4x F^{\mu\nu}(x)F_{\mu\nu}(x) $$ with $$ds=...
Hello,
I have a question about electron guns. I have read a lot, and all designs use high NEGATIVE voltage (-1000v for example). Is possible to use high POSITIVE voltage like this drawing?. Or do you think it will not work this way?
Considering that all the chamber walls are at ground voltage...
As we see in this Phet simulator, this is only the real part of the wave function, the frequency decreases with the potential, so lose energy as moves away the center.
we se this real-imaginary animation in Wikipedia, wave C,D,E,F. Because with less energy, the frequency of quantum wave...
during physics, I was chatting to a friend, and the conversation reached this question ,I know it is a series of probabilities, but how do we know for certain that it an individual particle, how do we know it is not just a field of energy? (Tell me if I sound stupid)
I tried asking a similar question in cosmology but got no answer there so here goes...
Suppose I am on a windowless spacecraft in the middle of an intergalactic void. I know that the spacecraft is spinning from measuring the centrifugal forces but have no way of observing the outside...
Hello,
Context is Inverse Compton Scattering with an pulsed electron beam interacting with a pulsed laser.
A laser has a Raleigh length of Z_r = w_o^2 * pi / lambda
w_o is the the radius of the spot size, lambda is the laser frequency.
I want to match this spot size to a pulsed electron bunch...
With regards to the number of states available to the electrons in these solids.
1. a mass of polycrystalline iron (plenty of free electrons)
2. quartz (has practically no free electrons).
3. semiconductors
Which of them has the most number of states available to the electrons?
Which has...
I've been thinking about this problem for some time now and think that I need to find E to solve for σ, but I have no idea how to go about that. How do I approach this problem?
Why there is not voltage or current just for 1ms if I connect a multimeter ground to the negative terminal of a DC power supply or charged capacitor? Why electrons in measure lead and DMM device cannot sense a bulk of electrons (or lack of it)? I tried with an 5kV DC power supply too. In an...
I connected a PVC insulated alligator clip test lead to a 12V (give 20V) DC power supply positive terminal and a multimeter. After that I connected an other one to the multimeter ground, and a third one to the power supply negative terminal. I turned the multimeter to DC V measure mode.
When I...
I figured that we would simply add up the forces acting on the electron (the electric force Fe and the magnetic force Fb) and then equate this to the given acceleration multiplied by the mass of the electron like so.
vector Fe + vector Fb = (mass of electron) (vector acceleration)
since vector...
There are two kind of electron configuration as I read so far.
There are one such as spdf and other such as, for example, 2 8 8 2.
What is the name of these electron configurations?
What is the difference?
My Textbook says this is the formula to find energy values for electron shells:
$$E_{mol of electrons} = \frac{-1312kJ}{n^2}$$
where $n$ is in electron shell number
But when we divide by 1 mol to get the energy value for each electron we get
$$E_{electron} = \frac{-2.178 \cdot 10^{-18}}{n^2}...
1) I know that the binding energy is the energy that holds a nucleus together ( which equals to the mass defect E = mc2 ). But what does it mean when we are talking about binding energy of an electron ( eg. binding energy = -Z2R/n2 ? ). Some website saying that " binding energy = - ionization...
So my thought process is as follows, since the initial centripetal force and the second magnetic force are working together, we can set up an equation to calculating final frequency.
However, I am struggling with how this can be done given so little numbers.
mvi^2/r + qvB = mv^2/r
Am I on the...
A free electron, or any other quantum particle, has an uncertain position/momentum, according to Heisenberg uncertainty principle. The squared amplitude of the wavefunction determines the probability of finding the electron at any point of the space. Accordingly, atomic orbitals are attributed...