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 all,
With the photoelectric effect is it the 'sea' of free electrons that are ejected if the photons are above threshold frequency (i.e. Conduction band electrons ) rather than valence electrons ? If say very energetic gammas are used then suppose this could knock out valence electrons but...
Homework Statement
The planet Jupiter has a moon Io. Volcanic activity on Io releases clouds of electrons which travel at high speeds towards Jupiter.
During a 15 s time period, 2.6 × 10^26 electrons reach Jupiter from Io.
Calculate the current.Homework Equations
I know current I = Q/t...
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?
I would like to ask how free electrons make metals conduct heat and electricity? Metals seem dull, their surfaces are shiny and reflect the light? So are these properties also related to free electrons?
I don't know true word for dull but it might mean the light cannot go through a dull object...
I have two questions... I'm sorry for my bad English.
- Is it correct to think of the Higgs Boson as a quantization of the Higgs Field, as the photon is the quanta of Electromagnetic Field?
- The property we call spin appears when we analyze electrons interacting with a magnetic field. But...
Please help me with this. I am having a hard time understanding the role of displacement currents in a circus. The common knowledge is actual current is the movement of electron in a circus. Now, if there is a gap and an AC source, there would be an electric displacement field and a displacement...
the current SM states that electrons, muons and tau are all different fundamental particles.
are there any theories that suggest there is only 1 fundamental charged lepton, the electron, and that muons and tau are either electrons that are in a higher energy quantum state, and therefore mass...
Homework Statement
The question states that an electron and positron, each with rest mass energy of 511keV collide head on and create a proton and antiproton each with rest mass energy 938MeV. The question asks us to find the minimum kinetic energy of the electron and positron.
Homework...
I watched a documentary about Quantum mechanics.
There's a phenomenon which Einstien called "spooky action at a distance" states that two electrons appeared in the same event are related to each other in a spooky way,which means that if one of them has a specific state then the other one will...
Homework Statement
The figure shows wire section 1 of diameter 4R and wire section 2 of diameter 2R, connected by a tapered section. The wire is copper and carries a current. Assume that the current is uniformly distributed across any cross-sectional area through the wire's width. The electric...
So, as far as I know free electrons are just electrons that have been 'released' from the shell of an atom and can now move. If this is true, what is it that causes the electron to become free in the first place?
Thanks in advance to any answers ☺
Homework Statement
Simple question we have to answer:
(Physics) How do I release the electrons from the cathode with a color filter? (The so called
Photoelectric effect)Homework Equations
none
The Attempt at a Solution[/B]
Here we have a conflict , the so called wave-particle duality, if...
I'm trying to understand (well, maybe in an oversimplified way) what permanent changes, if any, would be experienced by a positive electrostatically charged plate used to accelerate a free electron in a vacuum, but where the electron would not strike the plate.
I assume there would be some...
Photon is the force carrier for charged particles.
Questions:
1. Are photons generated between proton and electron in an atom?
2. If yes who generate the photon? The proton or the electron?
3. If yes, quantum mechanically, the electron is never at a fixed position, what is the photon doing...
Homework Statement
In solid state physics,we know all the states of free electrons can be expressed by the First Brillouin Zone. We know the $$E(k+K)=E(k)$$ where K is reciprocal lattice vector. We also know that the kinetic energy of the electron is $$E_{k}=\frac{\hbar^2k^2}{2m}$$. [/B]...
I understand that one way of creating quantum entangled electrons is by splitting a Cooper pair. Is then their spin property used in the measurement, as this must always sum to ##0## for a Cooper pair?
If that is the case, do quantum entangled electrons only exist in the singlet state, where the...
I have a simple doubt to keep things clear.
Why doesn't electrons fall into the nucleus of an atom?
Is it because of the high velocity of electrons?
If so, at what velocity will the electron be slow enough to collapse into the nucleus?
The problem:
A simple cubic metal has an electron density such that the Fermi energy just touches the edge of the first Brillouin zone. Calculate the number of conduction electrons per atom for this condition to be fulfilled.
The attempt at a solution:
I know that the electron density for a...
If you have a multi-electron atom and you swap two electrons around, what happens to the wavefunction? I think nothing happens because electrons are identical, but then they can have different spins, so would the wavefunction change if you swapped a spin up electron with a spin down one?
Hi.
Consider a simple circuit consisting of a voltage source ##U## and a load with resistance ##R##, e.g. a lamp or a motor. The current is given by ##I=U/R##. The number of electrons passing the circuit per second is ##n=I/e##. The power consumed by the load is calculated by
$$P=U\cdot...
Homework Statement
The beam of electrons in a cathode ray tube contains electrons traveling at 8.4x106 ms-1 and the current throgh the tube is 2.8 micro A.
a) how many electrons are emitted per second from the cathode of the tube
b) what is the number of electrons per unit length of the beam...
Basically, I'm asking about loosely-bound electrons, e.g. everyday static electricity. Can their combined wavefunction evolve to a low-energy state "at once", so that they emit a single high-frequency photon, rather than multiple photons of energies suggested by the potential difference?
If...
Homework Statement
In a group assignment we had to find out how many electrons were transferred to pieces of tape after we pealed them of a table.
The second part of the project asked us to imagine that one piece of tape was a distributed charge and that the other was still a point charge...
Homework Statement
Describe a method by which the charge / mass ratio e / m of the electron has been determined.
Calculate the deflection sensitivity (deflection of spot in mm per volt potential difference) of a cathode ray tube from the following data: electrons are accelerated by a...
Homework Statement
Two parallel metal sheets of length 10 cm are separated by 20 mm in a vacuum. A narrow beam of electrons enters symmetrically between them as shown.
When a PD of 1000 V is applied between the plates the electron beam just misses one of the plates as it emerges.
Calculate...
I'm taking a module in solid state electronics and I'm a bit confused with the energy band diagrams. I was told that the region between the top of VB and and the bottom of the CB is the "forbidden gap". However after learning about N-type semiconductors(silicon), I see that the extra electron...
Homework Statement
Two electrons in helium have ##l_1=1## and ##l_2=3##. What are the values of ##L## and ##S##? From this, deduce the possible values of ##J## and find how many quantum states this excited state of helium can occupy.
Homework EquationsThe Attempt at a Solution
For ##L## the...
Homework Statement
[/B]
An electron e- and positron e+ annihilate to produce two photons.
a_ Why are two photons produced rather than one?
b_ Assume that the e- and e+ are at rest just before they annihilate. In their rest frame, what are the energies and momenta of the photons? Define the +x...
Hello,
I'm a high school student interested in fusion. I've done a bit research online but I got a bit confused how does stellarator like W7-X drives electrons to run in the same direction without plasma current. I know in a tokamak, the plasma current makes electrons follow a certain direction...
Homework Statement
A metal sphere with a diameter of 10 cm has a charge distribution of 1.09085 x 1018 electrons/cm2 on its surface. What is the electric field strength at a distance of 25 cm from the surface of the sphere? (Answer: 5.5 x 1012 N/C)
Homework Equations
I wasn't given any...
Hi! I have a question about Linear Energy Transfer for electrons. According to the definition the linear energy transfer is equal to the energy dE which a charged particle loses at a distance dl. But what does dl mean in case of electrons? Is LET calculated per unit of full path length or per...
I don't understand why electron moves this way... e.g. A light object (crampled paper) going down until gets hit by the wind will go parallel (at least a few seconds) to the wind direction ... why not with electron?
heisenbergs uncertainity says that we can never predict the position and velocity of a particle exactly simultaneously. that is we can never be sure where an electron or a proton would be seconds from now. its all about probablity.
then how can these particles together form something like we...
This isn't really a homework question but I do have to know it for my lab report so I figure this is a good place to post it. So for my lab we had the setup that is displayed in the picture attachments. My question deals specifically with step #9 of the lab instructions. I'm assuming that the...
<--Why electrons move up if the Magnetic field is Horizontal?
at 0:14 <-- the Magnetic field is Horizontal but the electrons are also moving horizontally...
This is a multiple choice question that, after one incorrect attempt, I got correct; however, I want to actually understand what the explanation means. I'm hoping someone here can help.
Homework Statement
Two electrons, each with mass m and charge q, are released from positions very far from...
A friend of mine posed a question; if you take a rubber ball and bombard it with electrons, what would happen?
I posited that some of the electrons would likely stay on the surface of the ball, giving it a negative charge. I then suggested that if under the "right" conditions you may be able...
Homework Statement
Suppose electrons enter the electric field midway between two plates at an angle θ0 to the horizontal, as shown in the figure, where L = 5.1 cm and H = 1.1 cm. The path is symmetrical, so they leave at the same angle θ0 and just barely miss the top plate. What is θ0? Ignore...
Can high energy incoming protons and electrons be absorbed and their energies remitted by photons? If so what are the typical ranges of energies emitted and are they heading in the same direction as the original emission if we had a sheet of metal being bombarded by those protons and electrons?
I was reading this article: http://www.eurekalert.org/pub_releases/2016-08/ac-irj082916.php
The following paragraph has me scratching my head, wondering what they are talking about:
"The team studied what happened to the current passing through the exotic material zirconium pentatelluride...
If I shoot some free electrons detached from any atom in space from a space station what happens to the electrons? I know around the atom's nucleus electron creates cloud like movement having various energy levels. But what type of movement , cloud and energy the electron holds in absence of any...
Hi folks,
I just want to check I understand correctly the Schrodinger equation for two electrons.
https://en.wikipedia.org/wiki/Schrödinger_equation#Time-independent_equation
With control F you can find "two electrons atoms or ions" section.
Let's assume the wave function = x1 2+ x22 and...
So, I just had a thought about something I heard from Harry Potter a long time ago (not sure if it was from the films or the books-or both). One of the characters--I think it was Hermione--said something like: "Electronics don't work in Hogwarts." Or something to that effect--that electronic...
Hello everyone,
How can I calculate the partition function of N classical electrons (forgetting about the spin) in a box of volume V with Hamiltonian
(The Hamiltonian is missing a factor of 1/(2m))
?
I tried calculating the partition function of one electron first in the canonical ensemble but...
I've been pre-occupied with Heisenberg's uncertainty principle for around four years now, and I've come to fabricate a lot of questions.
The most pressing one, however, is as follows:
To me, the uncertainty principle seems to reference our (relatively) poorly controlled methods to measure a...