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.
Hello,
I would like to discuss with my students the deflection of electrons in electric and magnetic fields. For this purpose, I would like to perform the experiments with electron beam deflection tubes and teltron tubes. How would you implement this organizationally in the classroom? There are...
What I did was first noting that ##\hat{\vec{S}}_1\cdot\hat{\vec{S}}_2=\frac{1}{2}(\hat{\vec{S}}^2-\hat{\vec{S}}_1^2-\hat{\vec{S}}_2^2)##, but these operators don't commute with ##\hat{S}_{1_z}## and ##\hat{S}_{2_z}##, this non the decoupled basis ##\ket{s_1,s_2;m_1,m_2}## nor the coupled one...
B equals 50*10^-7 T (at first instance)
Fm equals 8*10^-20 N (at first instance)
I know Fm is perpendicular to the velocity, and I know the estimation of the trajectory (somewhat similar to the curve y=lnx).
Since I think vertical velocity will be constant, only changing the x component, I...
Hello All,
I am aware of databases which list possible gamma-gamma coincidences for desired isotope. For example: here provides a table at the bottom with all possible gamma-gamma coincidence for Co-60.
Question is, are there any similar databases/tables for electron coincidences with...
Imagine a magnet moving up and down so that its flux 'B' cuts the copper rod to produce an alternating emf, suppose if the movement is fast enough such that its frequency equals to the electron spin resonance frequency given by F = B x 2.8 Mhz per gauss, neglecting skin effect, more copper...
I have a question about what happen when an electron in the Bohr model of atom, gains energy because for example is "hitting" by a photon.
Electron have an energy, and it is the sum of potential and kinetic.
When they gain energy, they gain potential energy so they go further away from nucleus...
There is an optimum energy which gives the greatest probability of ionisation of a particular element.
This is said to align with the wavelength of the electron being close to resonances in the atom.
Looking at this in a different way as particles, would it be correct to say that the optimum...
I am very confused on how to go about with this question. The only thing I've tried so far is drawing the fbd of the electron and because of the plates the force applied would cancel which makes it centered between the two plates. As of now that is the only thing I understand, I am not sure how...
If ##\hat{T} = -\frac{\hbar}{2m}\frac{\mathrm{d^2} }{\mathrm{d} x^2}##, then the expectation value of the kinetic energy should be given as:
$$\begin{align*}
\left \langle T \right \rangle &= \int_{0}^{L} \sqrt{\frac{2}{L}} \sin{\left(\frac{\pi x}{L}\right)}...
Hi!
I'm playing around with a type of electron (and by electron/molecule interactions: ion) source that was briefly touched upon in the 1960's.
The basic idea is to use a channel electron multiplier "channeltron" with the anode removed; similar to a single MCP channel. The burst of electrons...
In quantum mechanics it is impossible to prepare an electron in a state where both position and momentum are known with arbitrary accuracy. In classical physics such states do exist, but can they be prepared?
If we assume that the electron is a classical particle (small ball of charge) can we...
Was there any study of this experiment in the context of classical electromagnetism? It is often claimed that such an experiment is impossible to explain classically, yet, the only classical model I've seen employed is Newtonian mechanics (bullets).
The EM fields associated with the electrons...
Hi all,
Why not build an electron rocket? Why won't this idea work? Seems like someone could just hitch an electron gun onto a spaceship. Boom! Electron Rocket.
I was thinking about ion thrusters. These use ions to achieve thrust. They are problematic for achieving a high delta V because...
I had two questions in the field of physics:
We know that in quantum mechanics there is an electron in a certain distance from the distance to the nucleus as a cloud or a cover. But is motion for the cloud defined by the electron moving around the nucleus?
And the main question is, can the...
I'm looking for a good derivation of the "wave" patterns in this experiment. I suppose that if wave-particle duality is an obsolete idea, there must be a derivation from quantum mechanics that gets close results.
Thanks in advance
Hello,
If I understand it correctly, the samples are grounded inside a scanning electron microscope (SEM) to avoid charge build up through the electron beam. Also the non-conductive are coated with a conductive layer, so they can be grounded as well.
However, I do not know how the charge build...
What is the quantum spin of the valence electron in the silver atom in
the furnace in the Stern-Gerlach experiment?
. Up, down, at random, alternating, in a (quantum) superposition (of
both), or none? Does it even have/get one until it's measured/observed
/needed?
. Does the second electron, in...
Hi,
It's not homework but I still thought I better post it here.
Please have a look on the attachment. For hi-resolution copy, please use this link: https://imagizer.imageshack.com/img922/7840/CL6Ceq.jpg
I think in equations labelled "12", 'e' is electric charge and Ex is the amplitude of...
The given diagram looks something like this:
Electric force on nucleus from external field must balance attraction force from electron cloud and electric force from external field.
$$e\vec{E}=\frac{k(\frac{L^3}{R^3}e)}{L^2}\hat{L}$$ where ##\vec{L}## is from center of electron cloud to...
The oscillator's initial energy can be found by considering when all of its energy is potential energy.
Eo = (1/2)kA2 = (1/2)mω2A2 = (1/2)me(2πν)2A2 = 2meπ2ν2A2
where me is the mass of an electron. With this in mind, the energy dissipated after one cycle is given by
ΔE = E(0) - E(1/ν) = Eo -...
Hi. I would love if someone could check my solution since me and the answer sheet I found online don't agree.
The probability is given by the triple integral
\begin{align*}
\int_0^{r_b} \int_0^{2\pi} \int_0^\pi |\psi (r)|^2 r^2 \sin{\theta} \,d\theta \,d\phi \,dr &= \frac{1}{\pi...
An electron is shot horizontally. There is a proton located somewhere else, but not in the horizontal path of the electron. Is there a distance of closest approach, and how do you derive it? A physical explanation would be appreciated too.
I am thinking about how an electric field has energy associated with it. If a single electron exists alone in a remote vaccuum, I believe it has it's own electric field surrounding it, and that this field has an energy content associated with it. My question is; does this electric field store...
From what I understand, electrons are negatively charged, however, I have recently come to learn that electrons also have a spin which creates a magnetic field around each electron. I don't understand how the electron can be a negative monopole, yet have a completely independent magnetic field...
Hi, I tried to solve this exercise but I'm not sure about the process.
First of all, I imposed that "K = E":
so that "v = √ ( (2q ∆V)/m))"
then I replaced in "r = m v / (| q |B)", v with "√ ( (2q ∆V)/m))", and found out that R = (2√(2)) r.
Then for the second point,
I imposed Lorenz Force...
In QFT where the electromagnetic field is mediated by virtual photons, is it possible to describe the larmor precession of an electron as a series of emission and absorption of virtual photons? how does the spin angular momentum "evolve" over a series of events? This feels like a challenging...
Basically the thread title. For some background, I'm trying to model laser-material interactions, where I'm assuming that the laser is interacting with a free electron gas (copper). To model the interaction, I need to determine the properties of the electron gas, such as the heat capacity...
Coulomb's law for three dimensional space is an empirical law that describes the forces between two stationary point charges and is defined as:
\vec{F}=\frac{K q_1 q_2 (\vec{r}_1-\vec{r}_2)}{|\vec{r}_1-\vec{r}_2|^3}
From Coulomb's law, the magnitude and direction of an electric field produced by...
So as the summary suggests, I am studying Electromagnetism, magnetic properties of matter and Magnetization vector in particular.
As a first example and to introduce the Magnetization vector (M), my textbook shows a ferromagnetic substance in a uniform magnetic field (B).
Then, every atom of...
In Theoretical Minimum: Quantum mechanics, Leonard Susskind describes an electron in the higher energy spin state in a magnetic field radiates a photon of energy ##\hbarγ|B_0|## and flips into the lower energy spin state. I am wondering if this photon is related to the "virutal photon" that...
Hello, I'm new here and honestly I'm not a physics student. I'm studying engineering and so, understand little of physics. I am trying to find the bond force of graphene's free electron. That means, the electromagnetic force by which the electron is bound to the nucleus. I can only calculate it...
Electrostatic repulsion of two electrons is about 4.17*10^42 stronger than their gravitational attraction, and is mediated by massless carriers. Black holes preserve charge, and charging a BH with even a moderate electric (negative) charge will result in BH repulsing electrons instead of...
Any spinning item, proton, electron, even planet, has angular momentum that creates force. How can an electron exist in a random orbital cloud around a spinning proton if it has an angular momentum and requires force to alter from any circular orbital plane (like a planet orbiting a star)?
I am only asking about part e. If you are short on time, you can read through parts a - d, to get an idea of what is happening, and then attempt part e directly.
I have solved parts a - d. If you would like to check your answers, the answer to part c is [rne^2 / 2e0] [ 1 - (v/c)^2], and the...
Energy is equal to Planck’s constant times the number of waves in 1 sec. The time scale for electronic excitation is far shorter then one second. So when we talk about the excitation of an electron from a lower level to a higher level occurring at a certain energy, are we talking about the...
As we know that An electric current is a flow of electric charge in a circuit and In electric circuits the charge carriers are often electrons moving through a wire.
Now, since we know that Like charges repel each other then how do the electrons flow through a wire since they are like charges...
So I can find the initial momentum using p=h/wave = 4.98 x 10-23. Now my problem is that I don't know the final momentum of the photon nor electron, I just know the photon is scattered at an angle of 34 degrees.
I know how to solve this problem if I was given the final wavelength of the light...
In absence of a positive electric field created by proton what type of behavior an electron shows? I am talking about a free electron like from a electron gun in deep space . Pauli's exclusion, orbitals, energy level etc. which are normal in an atom for electron will be absent for an electron...
I am trying to draw the Poynting vector field for a single electron in free space between two capacitor plates. The electron is moving (and accelerating) to the positive plate at the right. I expected the Poynting vector field lines to converge to the electron, because that is where the work...
Here's the question ^
My first thought to solving this is to use Heisenberg's uncertainty principle. $$\Delta x \Delta p = \frac{h}{4\pi}$$ Now, we approximate ##\Delta x = \frac{L}{2}##. Then, plug and chug we end up with:$$p =\frac{h}{2\pi L}$$
I thought this was it, especially because this...