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.
As a hydrogen atom approaches a Neutron star, is the probability distribution of eigenstates of the electron in that atom influenced by the gravitational field of the star?
Hi! I recently learned about the Alpha decay, where the atomic Nukleus emittes Alpha-Particles. I was wonderin if a material, which emittes such Alpha Particles has a surplus of electrons and so a negativ electronic charge after the decay. Because it loses Protons but stays with the...
So we know for a fact that an electron is a particle. The "wave" like properties are not waves at all, its just the wavefunction that is a mathematical wave which is used for getting probabilities for where the electron will end up.
But what about a photon? When a charge oscillates, its gives...
Homework Statement
A proton is at the origin and an electron is at the point x = 0.36 nm , y = 0.34 nm.
Find the x- and y-components of the electric force on the proton.
Homework Equations
E = kQ/r2
The Attempt at a Solution
So I found that E = 9.38 * 10-28, but my problem is that I do not...
Homework Statement
An electron and a proton are held on an x axis, with the electron at x = + 1.000 m and the proton at x = - 1.000 m. If a second electron is initially at 20 m on the x axis, and given an initial velocity of 350 m/s towards the origin, it does not reach it. How close to the...
So in MWI, the electron takes many paths through the double slit experiment and each path is in a different world.
So if electrons are fired one at a time, what makes an electron go on a certain path. Say it goes on some weird path that would have implied that a force exist when viewed...
I mean for the free electron Dirac equation the charge (e or q) does not appear in the equation. It only appears after its interaction with EM field. So it seams the electron does not have the intrinsic property of charge, either that or the EM is integral to the electron. Any idea?
Today I was doing some reading and I came across this topic. If we have a stationary hydrogen atom with a single electron in orbit around the nucleus and want to calculate the kinetic energy of the electron we would take the following approach.
1) Using Newton's second law:
F = ma ⇒ FE = mac...
Homework Statement
The question is based on the Bohr model with an electron with charge e and mass m orbiting a proton about a circular radius r.
I have to find k in the equation I = e2 / sqrt kε0r3m
where k is a some combination of constants.
Homework Equations
Coulumb's force law: F =...
S. Weinberg says in his book, "The Quantum Theory of Fields Volume I", that
Since electrons carry a charge, we would not like to mix annihilation and creation operators, so we might try to write the field as $$\psi(x)=\sum_{k}u_k (x)e^{-i\omega_k t}a_k$$
where ##u_k (x)e^{-i\omega_k t}## are a...
Hello, first post. I recently became interested in quantum physics and its mysteries. To my understanding, In the double slit experiment, the photon or electron will scatter and behave like a wave when both slits are open and neither slit is measured. Over time their cumulative scattering mimics...
Homework Statement
An electron is fired at 4.0x10^6 m/s horizontally between the parallel plates as shown, (see attachment) starting at the negative plate. The electron deflects downwards and strikes the bottom plate. The magnitude of the electric field between the plates is 4.0 x10^2 N/C. The...
So for what I understand, when a star collapses, the electrons do not like to overlap their quantum states because of the pauli exlusion principle. Is this different from an E&M force? If so, then why isn't it a fundamental interaction? All forces are made of a combination of the 4 fundamental...
Homework Statement
https://imgur.com/zEoCpc0
I am trying to figure put the angle and my attempt is tanx=sy/sx (I have calculated a value for the distances)
But my book is saying: tanx =vy/vx
I don't understand why my way of solving it is wrong... I don't get the same answer for x :/
When beryllium donates a pair of electrons to oxygen, that's oxidation, and the metal is Be(II).
When carbon and oxygen share 6 electrons, 2 from carbon and 4 from oxygen, this is also oxidation. Of carbon. Even though it got more electrons, and even, I heard, has a negative charge.
When...
Homework Statement
An electron is launched between two parallel, neutral, conducting plates that are each L long and separated by a distance d with a uniform magnetic field of magnitude B permeated between them.
(a) What is the minimum speed the particle must have to traverse the region...
I am having difficulty thinking through how a ferromagnetic substance is permanently magnetized.
I think I understand that when for example a sample of iron is heated above it curie temperature and then exposed to an external magnetic field , the sample will become permanently magnetized. The...
Homework Statement
An electron in the Coulomb Field of the proton is in the state:
|ψ> = (4/5)|1, 0, 0> + (3i/5)|2, 1, 1> with |n, l, m> as the quantum numbers defining the state
a) What is <E> for this state? What are <L2> and <Lz>?
b) What is |ψ(t)>? Which expectation values...
In QED, 'electron self energy' to first order results from an electron emitting and reabsorbing a photon.
But surely the emitted photon can be absorbed by any other electron in the universe, not just the emitting electron? Indeed it makes no sense to say the photon is absorbed by the same...
Homework Statement
In pyrrole the electron density is maximum on which carbon atom? so if the numbering starts from nitrogen, the carbon on the right side of nitrogen let it be numbered as 2 and the next one as 3 and so on... which of the following options will have the carbons of maximum...
Homework Statement
The system consists of a long cylindrical anode of radius a and a coaxial cylindrical cathode with radius b (b <a). On the axis of the system has a thread with a heating current I,
creates in the surrounding magnetic field.
Find the smallest potential difference between the...
I was reading through a thread and read someone say that there is really only one electron traveling through time which is why all electrons we see are the same. IS this an accurate claim? if so, where does it come from?
Homework Statement
This is what the question looks like and I don't even have an idea where to begin since we didn't really cover this during lectures.
Homework Equations
This is all I have from my notes:
also I found that Eg=Ec-Ev
Any help appreciated
Thanks
In classical Physics wave theory (GCSE level) we talk about waves diffracting through a gap if the gap is similar size to (or smaller than) the wavelength of the waves.
When firing fast electrons at a carbon target (teltron tube A level type apparatus) is it sufficient to say that if the de...
If Energy levels differ in accordance to the orbital, say like 2s and 3d orbitals, then shouldn't the mass of the electron then change to uphold E=mc^2?
Or is there something I am missing?
Homework Statement
A 2 GeV electron is incident on proton (m_p * C^2 = 0.938 GeV) target at rest. Calculate the invariant mass of the electron-proton pair in the Center of Mass(CM) frame. Neglect the mass of electron which is much less than the proton mass.Homework Equations
M = [P1 + P2)][/2]...
I understand the electron in the situation to be rapidly accelerated away from the torroid. If this is true, my question is:
Will the electron emmit radiation following the synchrotron formula?
Also, would the radiation travel through the torroid?
Take the case where the electron-beam is oscillating between two parallel metal plates, there will be alternating potential developed between the plates as metal tries to negate all external electric fields.
My query is,
(1) How to calculate the potential developed and possible way to simulate...
Homework Statement
Hello,
I'm asked to show the equivalence of the given Hamiltonian below which describes the interaction between an electron and a nucleus
and the following Hamiltonian
The Attempt at a Solution
[/B]
I've simply written down each Hamiltonian as a sum of four tensor...
Let's say we have a transition from state 2p to 1s of an hydrogen atom's electron. The intensity radiated by the electron is given by I = 4/3 ωfi4 e2/c3 |< f | r | i >|2.
If we take the the | 2 1 1 > → | 1 0 0 > transition for example, we must compute the following integral :
< f | r | i > =...
I read somewhere that an electron travels forward in time and a positron travels backwards.And when a photon hits the electron the direction of time for it reverses and it becomes a positron.Does an electron really turn into a positron when hit by a photon? why?
Hi guys! I have a problem with this exercise:
1. Homework Statement
The stars called white dwarfs may have inside them a density in order of 1011 kg m-3. For semplicity, we assume:
these stars are made with non interacting protons and electrons at the same quantity and with uniform density...
Millikan Oil drop experiment.
For my current lab, we are recreating the milian oil drop experiment to measure the charge of an electron. However, we are using 1-micron diameter latex spheres in place of oil drops.
Problem:
I am having difficulty deriving an equation for the speed of the drop...
Homework Statement
I'm taking a module in Solid State Electronics and in the first chapter we went through energy band diagrams, conduction band, valence band, fermi energy level, forbidden gap, etc. Now in the notes it starts to derive some formulae for electron and hole current densities
Jn...
I am wondering about the minimum possible uncertainty (standard deviation) in an electron's position (Δx). How precise can one know the electron's whereabouts without creating other sorts of particles and phenomenons.
I know of the localization energy interpretation of the energy uncertainty...
Homework Statement
An electron is shot towards an infinitely long wire with high current flowing througuh it.
Please, look at my "sketch" in the attachment.
How will its trajectory be affected? What curve will it be?
2. The attempt at a solution
I thought about circular motion, but the fact...
Homework Statement
In a potential box (##L = 1.00pm##) an electron moves at a relativistic speed, meaning it's momentum can't be expressed as ##P = \sqrt{2mE}##.
a) Using the uncertainty principle, show that the speed is indeed relativistic
b) Derive an expression for the allowed energy states...
Homework Statement
I want to derive the following equation. It is the potential energy of an electron inside a nucleus assumed to be a uniformly charged sphere of R.Homework Equations
V'(r) =( -Ze2/4∏ε0R)(3/2 - (1/2)(r/R)^2)
The Attempt at a Solution
I get E = Ze2r/(4∏ε0R3)
But I am having...
I have read the description of electrons as standing waves based on an analogy with a string vibrating at its natural frequencies: thus the different quantum levels are akin to the tones or harmonics of the string, right?
So far, so good, but then I have seen contradictory complementary views...
Homework Statement
So my teacher set us half term homework and one of the questions was state the relative size of a proton a neutron and an electron
Homework Equations
Not sure about equations
The Attempt at a Solution
Im a bit confused because everyone in my class got
Proton: 1
Neutron: 1...
According to quantum mechanics, an electron possesses orbital angular momentum. And we know that orbital angular momentum is possessed by revolving body. Does electron revolve around the nucleus? Please explain. I shall be very much thankful to you.
Ran into a question in my amateur research. Been waaay too long since college physics, and I've exhausted searches. This is the theoretical question:
Assume a non-conducting, infinite plane charged to +10 kV. An electron leaves perpendicular to the surface with an energy of 10 keV. How far...
I am in the midst of a discussion with someone who feels very confident that an electron is always and forever a point particle and never a wave; any wave-like behavior that is observed must be attributed to a pilot wave that guides the path of the electron.
I have sought to argue that this...
Homework Statement
Write the electron configuration for Cd 2+.
Homework EquationsThe Attempt at a Solution
[Kr] 4d10
Whenever we remove electrons do we always remove it from the s orbital in that period. So for cadium ion we remove 5s2 correct? But let's say it's Mn 2+ would we remove the...
Homework Statement
In a measurement of the electron charge by Millikan's method, a potential difference of 1.5 kV can be applied between horizontal parallel metal plates 12 mm apart. With the field switched off, a drop of oil of mass 10-14 kg is observed to fall with constant velocity 400 μm...
I've been reading up on electron diffraction for electron microscopy, and I have been trying to understand the proof for the wavelength of an electron in a tunneling electron microscope. The proof I have been trying to emulate begins as follows:
It then says that I must account for...
I have been researching wave/particle duality, and I have trouble comprehending how electron microscopy actually exploits wave/particle duality to operate.
From Wikipedia, "
Wave–particle duality is exploited in electron microscopy, where the small wavelengths associated with the electron can...