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.
Good evening guys,
I have to give a talk to my thesis on Friday, and I would like to show a simple animation of electrons moving in a metal according to the Drude-Lorentz model.
In this model, the electrons are classical particles that elastically scatter at spatially fixed atomic cores which...
I have heard that wavelike interference patterns are observed in the double slit experiment even when electrons are fired one by one.
https://physicsworld.com/a/the-double-slit-experiment/
My knowledge on the experimental setup is very basic. The reason I am posting here is out of curiosity...
I understand that the energy of an electric field arises from the work put into gathering the electrons together to create the field. Bringing electrons close together requires energy because they naturally want to repel. This potential energy is stored in the field itself and the field has an...
In 8a) I don't understand the question, does spin = 1/2 mean the magnitude of the spin or the z-component of the spin is 1/2? Can the electrons possesses be any of the spin=1/2 or -1/2? Are the electrons distinguishable?
In https://en.wikipedia.org/wiki/Lamb_shift about the lamb shift, it's mentioned that the change in the electron's frequency due to QED effects (vacuum polarization and self-energy correction) is about 1 GHz, which would translate to an energy change of hf = 6.63E-25 J. This is 3E-7 times of the...
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...
The full questions is in the picture. I already solved a) and found 5.6E14 electrons per second
For b) i first found the power of the light but just multiplying the intensity with the area: (6.0 W/m2)(3.5E-4 m^2) = 0.0021 W
Then I tried to use the voltage from the graph but i am not sure which...
we know that when a electron lost its energy , it will emit photon , but why electron have a photon inside ? does it already exit in a electron from the beginning or it comes from environment ? if comes from environment , where does photon come from?
I'm a bit confused as to why can't you transmit AC current over a single wire.
For instance, say you have an AC generator which induces potential difference at different points of the wire and thus, creating current. Downstream, the wire can be split and applied to a load. When the wire is...
If at high energies the electromagnetic and weak force are combined into one electroweak force, then at high energies, the electrons will not create an electrostatic field and will not repel?
Homework Statement
I learned that Covalent Bonds form between different specific atoms ( with similar electro-negativity ) with electrons.
However, I wondered what type of bond would form between the different atoms if they had no electrons?
Also , if I have 2 atoms with similar...
The two electrons will be repelled by electrostatic force, but they interact with weak force, means that in addition to the electrostatic force between the electrons there will be weak force?
My concern is an electron tube.
From what I understood so far, gas molecules will have an average velocity derived from the Maxwell distribution, and that velocity will influence in the electron collision frequency.
I can't see clearly though how the electron velocity itself in the presence...
If an electron is divided into quasiparticles in a material, then at the contact between the two materials does the interaction only occur between holons, since they carry a charge?
Hi i am posting this to double check my work. Please help and feel free to ask any questions. I posted a picture of my work and what i currently have.
1. Homework Statement
Two small insulating objects are hung from strings attached to the ceiling. The masses of each object is 0.0076 kg. The...
I'm looking for images of electron or ion beams recorded (from the side) using electrons, for example with a transmission electron microscope. Does anybody have references to publications?
How do I work out the voltage between two stationary electrons a given distance apart apart?
I understand the definition of a volt and I guess that I would need to use Coulomb's law and integrate with respect to distance. It would be great to see the maths though as the answer that I got seemed...
I am reading and trying to understand “Spooky Action,” an article that has been published in Scientific American, December, 2018, starting on page 60. To begin:
1) How does one create a pair of entangled electrons, especially with spin sideways?
2) How does one then isolate one electron from...
Is the wave function for the positron the complex conjugate of the wave function for the electron? I've tried to google this, but I can't seem to get a definite answer from a reliable source. It seems that antimatter is derived in quantum field theory which does not concentrate on wave...
Hello ,evreyone.I have two questions about fermi energy.
1,Can I claim that 'fermi energy ' play the role of chemical potential?
2,I have learned from thermal physics that only electrons near fermi level can conduct in metals.How can electrons behave like this? I can't figure out why only...
Hello,
this is my first forum question, so i hope it's at the right place.
My question is about electrons, i know in a QM view electrons don't have a well defined position or speed.
However i am curious, in a classic view of the electron would electrons closer to the nucleus move faster then...
Electrons and positrons are assumed to be point masses. Two points presumably can never actually touch. How close do they have to be before they annihilate each other?
If electrons move as current flows through a conductor, what happens when a wire is grounded? Do electrons flow in the ground??
If they do, will it effect the number of electrons in the circuit which starts from power plant such as dam and comes to our homes through a grid station?
Will it not...
Suppose you have a pair of electrons in the same quantum state, and are thus spin entangled, and they absorb a pair of photons and release them at the same time. How would this affect the photons? Would the photons be entangled? Would it affect the photon spin, and if so, how would it affect the...
Hello, I don't understand how can electrons in triplet state can have the same value of spin? Shouldn't the spins be different because two fermions can't have the same state?
The following picture explain my question in more detail.
Historically, quantum mechanics, or wave mechanics, arose due to the anomaly that accelerating free charges ( electrons ) radiated EM waves. The quantisation theory provided a solution.
Quarks also have electric charge, and are moving at relativistic speeds, and bound in the nucleon.
As the...
Please let me know if the following reaction is possible for high energy electrons colliding with neutrons or neutron-rich nuclei:
n+e^{-}\to \Delta^{-}+\nu_e.\tag{1}
If it is forbidden for some conservation law or for some other reason, please give me an explanation why. This reaction is...
Homework Statement
Long and thin sample of silicon is stationary illuminated with an intensive optical source which can be described by a generation function ##G(x)=\sum_{m=-\infty}^\infty Kδ(x-ma)## (Dirac comb function). Setting is room temperature and ##L_p## and ##D_p## are given. Find the...
When an electron leaves a conductor and tunnels through a thin dielectric; how does it behave in the space occupied by the dielectric? Does it behave like a ballistic electron traveling through vacuum? Is it instead that the electron never really occupies the space in the dielectric?
In electron cyclotron resonance of metals/solids can there be electron acceleration without them engaging in collision ? I read the last para of electron cyclotron resonance wikipedia page which stated this
In @A. Neumaier 's excellent Physics FAQ, he notes under "Are electrons pointlike/structureless?" that
"Physical, measurable particles are not points but have extension. By definition, an electron without extension would be described exactly by the 1-particle Dirac equation, which has a...
Could one make a negatively-charged insulator with the extra electrons trapped all the way through its volume by building it up layer by layer with electrons "sprayed" onto each layer as it was constructed?
I guess the electrons would be trapped in empty atomic orbitals within the material - is...
If an electron is moving in a circle in a magnetic field, it produces a magnetic field in accordance to the right hand rule. If a proton is moving in a circle in a magnetic field, would it produce a magnetic field in accordance to the left hand equivalent to the right hand rule.
Can you store them in a tungsten chamber without using any magnetic fields. And without any magnetic field will they leak out because of the size difference between electron and tungsten atoms. CERN was able to do it with it LEP collider (electron positron collider) so if any of the CERN...
I have always been interested in entagled electrons. so I thought about the stern gerlack experiment and simly wondered what would happen to entagled electrons in such an experiment. (although the prefix says high school i am able to appreciate more complicated answers).
Homework Statement
The accelerating voltage in a cathode ray tube is ##1000 V##, the electron current density is ##150 \mu A##.
a) How many electrons arrive at the screen in a second?
b) What's the magnitude of the force exerted on the screen by the electrons if they stop on collision?
(Sorry...
The Atom of Helium is doubly excited in 2p2 1D
Can someone explain to me how these energy symbols work? I have a problem with what the 1D means specifically. I know 2p2 means two electrons in the 2p state. The 1 in 1D could be referring to electron being in a singleton, but I don't understand...
Homework Statement
Given Slater's expression for effective charge below, determine the effective charge experienced by the valence electrons of Sb.Homework Equations
Zeff = Z - 0.35a - 0.85b - c
Where
Z= the nuclear charge; a= the number of s and p electrons in the same shell; b= the number of...
Phonons on their own lead to the common heat equation. One sees that for example in insulators or non doped semiconductors.
However in metals (or conductors), the electrons are the ones that are mostly responsible for the heat transfer, which extremely surprisingly to me, is also of the form of...
I was watching this video ( ), and around the 1:52 mark the woman said that it is impossible to image molecules with visible light. By her demonstration, I took this to mean that we can't use visible light to image molecules because visible light is too large to be reflected by the molecule...