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.
Firstly sorry for my english .
I don't know how i should search this question this is why i am asking here.
while i am thinking about charges,i think
consider a positive charge. And put an electron very far from it. Is there any posiblity for electron don't affect from positive charge
Why is the number of doping unrelated to the amount of current produced by solar cells? Suppose GaAs and Ge with the same amount of doping. Where is the role of an electron generated by the donor?
Consider hydrogen and helium. Both have electrons in energy level 1. When the electrons move from level 1 to a higher level, are the energy quantum the same for the electrons in hydrogen as in helium? If so, then how can one distinguish hydrogen from helium by observing the emitted light...
I've read that if you apply enough voltage to the plate of certain types of tubes, they will generate a fairly good amount of X-rays (even more so if the cathode is hot) -- I even read about a guy who managed to take relatively detailed radiographs of random objects using a standard...
After an electron absorbs a photon, it will move to a higher energy state. It then releases a photon and returns to its ground state. But why does the electron release the photon? Why does it not remain in that energy state? What forces it to return to ground state?
Hi.
I am just starting to self-study particle physics. Came across the following in some notes -
Electron and positron annihilate to form a photon with zero momentum. I thought all photons had momentum due to the de Broglie equation ?
Also 2 electrons scatter to form a photon with zero energy...
If you know where to look for an electron (e.g. in an atom or an experimental setup) it is quite understandable that, until you know exactly where it is, there is a calculable probability of where it might be. However, if we take the case of an un-associated electron in space, it would seem that...
Kind of the basic question of atomic physics is momentum distribution of single electron of ground state hydrogen atom - especially the power in its high-energy tail (HTMD: high-tail momentum distribution), which should have strong impact especially on various scattering experiments.
Fock's 1935...
Guy guy, i just learn a little bit about quantum physics and i know that electrons is not particles.
But i don't understand how it move.
By the way I am only a secondary school student.
If you explain it clearly and easy to understand i'll be very happy.
But thank you all for taking time to help me!
Hello mates. I was doing some research about Rydberg atoms, and I came up with this question: what's the energy of an electron in n energy level in an atom which is NOT hydrogen-like, that is, an atom with more than 1 electron? How can we calculate it?
What if the electron we are studying is in...
Theres something that bothers me, We claim that electron is a point particle.From that,
Can we assume the volume the electron is ##(l_{h})^3## ( where ##l_h## is Planck length ) ?
We know that every information can be described in bits like volume is ##(l_{h})^3## so, In every bit of...
I know that my title is not very suitable for this question, but I couldn't find right words to describe the situation.I read a book called '101 Quantum Questions ' and there writer states that when electron absorbs energy and goes higher energy level, we don't know when and where it will come...
Why is a sea of electrons present in a conductor?
I read some where that they absorb a energy at normal temperatures and use it to get free electrons , but then why do they absorb energy while insulators don't??
so I am finishing up my studies of intro to quantum mechanics, and this is not in my book and looking at previous exams i have to know this for single electron atoms/ions.
one of the problems was somethin like
"the wave function of an electron is the overlap of the orbitals:
Ψ=aΨ1s+i/√3Ψ2p+¾Ψ3s...
In SI units, the mass-to-charge ratio of the electron is
$$\frac{m_{e}}{|q_{e}|} = \frac{9.11 \times 10^{-31} \text{kg}}{1.6 \times 10^{-19} \text{C}} = 5.7 \times 10^{-12} \text{kg/C}.$$
In which system of units do we have the dimensionless mass-to-charge ratio
$$\frac{m_{e}}{|q_{e}|} \simeq...
This is not a homework, but a question formed in my mind after reading my textbook.
Homework Statement
Consider an electron (a charged particle) on a metallic equipotential surface. We know that all the points on the surface are equipotential, thus there will be no force on charged particles...
Homework Statement
There is a sample problem in my physics textbook (Fundamentals of Physics, 10th Edition by David Halliday and others) which has some confusion in it for me. Please take a look at the snapshot I took, in the attachments.
Homework Equations
3. The Attempt at a Solution [/B]...
Hi,
How can I relate the beam energy of an electron beam produced by an electron gun to the accelerating potential? I realize that accelerating potential, initial energy (before acceleation), and losses by synchrotron radiation, etc, will play a part.
I searched online and can't find much.
Thanks
Homework Statement
Homework Equations
1/2 mv^2
E = hf
c = f (wavelength)
The Attempt at a Solution
0.5 * (9.109 * 10^-31) * (6 * 10^4)^2 = energy
energy = hf => f = energy/(6.626*10^-34) = 2.47 * 10^12
wavelength (m) = (speed of light) / frequency
wavelength (m) * (1*10^9) = 121235.4
Answer...
I know this question might be too simplified but, What is the primary causes generation of light (electromagnetic waves) by electron? Is it vibration motion of electron or the motion of electron around the nucleus?
Homework Statement
An electron in a cathode-ray tube is accelerated through a potential difference of 10 kV, then passes through the d = 2.4-cm-wide region of uniform magnetic field in the figure(Figure 1) .
What field strength will deflect the electron by θ = 13 degrees?Homework Equations...
I have read in textbook that if a photon were to collide with a free electron it's an impossible situation for photon to get completely absorbed by an electron .
The situation seems possible by conservation of energy but I am not able to understand the true reason behind the statement .is there...
Hi folks,
I am reading "Purcell Electricity and Magnetism" and in the problem 1.77 he says:
"
Imagine a sphere of radius a filled with negative charge of uniform
density, the total charge being equivalent to that of two electrons.
Imbed in this jelly of negative charge two protons, and assume...
When a nucleus captures an electron from the innermost orbit, its proton number reduces one. Therefore, energy levels in the atom have to change accordingly, meaning all the electrons have to move lower energy levels. From this point of view, during an electron capture, can it be said that the...
Hi,
I'm currently investigating magnetic fields/their cause. This has inevitably led me to learn all about electrons. Here I want to post my understanding on electron 'spin' so people can correct me if I'm wrong/help others get a better understanding.
So I watched this YouTube video for...
Hi all,
This is likely a naive question, following up on something @vanhees71 posted some time ago in another thread:
My question is the following - if we take an electron that has, for example, absorbed a photon, is the portion of the wavefunction representing the electron in a lower energy...
Hello,
An electron accelerated through a pd of V volts will have a K.E = eV. Why isn't the K.E less than this considering that some of the work done by the field has been radiated as electromagnetic waves by the accelerating electron ?
All insights very welcome.
Lets pretend there is a gun of some type that can fire electrons one at at time at a wall. The plane of the wall is oriented perpendicular to the x axis, which is to say that the wall is in the y-z plane some distance down the xaxis.
There is no intervening screen with slits in it. We are just...
Homework Statement :[/B]
Velocity of an electron at point A1 is Vo where cross sectional area is A. The velocity of electron at the end of contraction at point B where cross sectional area is 2A is V1.Find correct option
a)V1< V0
b)V1= V0
c)V1> V0
d)V1<=V0/2
I have attached a picture of the...
Homework Statement
Consider Compton scattering of a photon by a moving electron. Before the collision
the photon has wavelength λ and is moving in the +x-direction, and the electron is
moving in the −x-direction with total energy E (including its rest energy mc2). The
photon and the electron...
I mean, we defined a second to be the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom [copied from wikipedia].
A meter is the distance traveled by light in 1/299792458 second.
Why can't...
Homework Statement
what is the value of ni for an electron that emits a photon of wavelength 93.14 nm when it returns to the ground state in the hydrogen atom
Homework Equations
planck's constant 6.63 x 10^-34
The Attempt at a Solution
no idea [/B]
Imagine we take a vertical, infinite wire and we let electric current pass through. The charges create magnetic field all around the wire.
Now if we introduce an electron in the magnetic field, it will have a circular motion around the wire. The Lorentz force is not conservative, this means...
Hi everyone,
I am just wondering how to calculate electron distribution using tight binding band structure for a system like graphene or any other solid.
So the goal is to get |\psi(r)|^2 which \psi is the band state and it is the linear combination of Bloch sum...
As we know from special theory of relativity, time flows slower for a moving observer. But also, thanks to gravity, time ticks slower and faster depending on whether the gravitational force is stronger or weaker. This f.ex. means that time will flow slower for a person living on the 10th floor...
Hello,
I have a presentation tomorrow and in a segment, I talk about light absorption. It's more conceptual than technical. I did quite a bit of research on the topic but because of simplifying information I may have butchered the facts and written something wrong. Could anyone please confirm/...
Homework Statement
I am having trouble with part d, where they ask me to prove that the wave function is already normalized
The Attempt at a Solution
But that clearly doesn't give me 1. I tried to use spherical coordinates since it is in 3D? Not really sure how to proceed.
EDIT: I realize...
Homework Statement
Consider an electron described initially by ##\psi = \frac{1}{\sqrt{10}} \begin{pmatrix} 1\\ 3 \end{pmatrix}##. A measurement of the spin component along a certain axis, described by an operator ##\hat{A}##, has the eigenvalues ##\pm \frac{\hbar}{2}## as possible outcomes (as...
http://www.nature.com/news/not-quite-so-elementary-my-dear-electron-1.10471
So when the electron is in the material, it separates into 3 different quasiparticles. But then it says that they cannot exist independently outside of the material. So does that mean the 3 quasiparticles are always...
Homework Statement
Hey everyone,
So my teacher assigned a mini project just before our finals and I was wondering if someone could look over my work and my calculations. I just want to make sure I understood everything since my final exams are coming.
Here's the assignment.
Compare and...
http://www.nature.com/news/not-quite-so-elementary-my-dear-electron-1.10471
It was found out that electrons are made of quasi particles. But kind of fields are the quasiparticles made of?
https://link.springer.com/chapter/10.1007/978-3-540-39664-2_1
http://iopscience.iop.org/article/10.1088/0031-8949/1988/T22/016/pdf
In these two experiments done back in the 80's, electrons were trapped inside a penning trap for long periods of time. They were measuring the ratio of the magnetic...
Hey,
I am studying Spin 1/2 system, the case of 2 electrons in a magnetic field, since we have 2 electrons, we expect that the matrix will be of the size 4x4, which is what I have got.
As I know that I could use the density matrix to calculate the expectation values of any physical quantity...
I wonder if this question will make sense, but I will do my best shot:
As the electron orbits around the nucleus, I imagine there are moments when it is too far away, so it starts to be "pulled toward" the nucleus. If it gets too close, it will be "pushed away". If it is in the orbital area...