Electron Definition and 999 Threads

Homework Statement How much work is required to stop an electron (m=9.11×10−31kg) which is moving with a speed of 1.40×10^6 m/s ? 2. Homework Equations The Attempt at a Solution E.g a particle has KE=10J. The work that must be done on it to stop it is -10J. So work out the kinetic energy...

How might we construct a state most closely corresponding to the idea of a single electron wave packet as some superposition of Fock states?

U(x,y,z,t)*ψ(x,y,z,t)-(ħ/(2*m))*(d2ψ(x,y,z,t)/dx2+d2ψ(x,y,z,t)/dy2+d2ψ(x,y,z,t)/dz2)=ħ*i*dψ(x,y,z,t)/dt qproton=-qe Schrödinger equation for electron in hydrogen atom (if we consider proton as point charge which is moving at a constant speed vproton→=(vp;x;vp;y;vp;z).) is...

Where from do the electrons in an atom get the energy to keep constantly moving around the nucleus of an atom

If electron can show behaviour of wave in double slit experiment like interference, diffraction, can it pass through fibre optic cables, if it is accelerated with high speed into the cable?

Is there an electric or magnetic field from the electron present in the deconstructive regions of the electron interference pattern?

Not quite sure how to ask this, but here goes: I think I understand how a photon impacting an atom can increase the energy level of an electron in the atom. When I read about "light pressure", I thought, is there a way for, say, a stream of photons to accelerate an atom by continually impacting...

Hi all, I am currently writing a report about superconductors, and am currently reading about how the band gap shows that single electrons are not the charge carriers responsible for superconductivity. However, I was confused when I read that electrons are fermions and as such there are no band...

Hi, is it true that the heavy atoms decaying only by electron capture should have globally a half-life shorter than ligher nuclei (decaying also only by electron capture)? This assumption comes from the fact heavy atoms have inner electron "closer" to their nucleus than the lighter ones and so a...

Spin is an intrinsic property of particles meaning that they have it naturally. Electrons can have either +1/2 spin or -1/2, what dictates that it is one instead of the other?

Hey! I am trying to figure out this one problem. Some help would be appreciated. How can i relate the maximum distance traveled by an electron at a given pressure? So electron is colliding with air molecules. I wonder if there is a formula or derivation which relate maximum penetration and...

Has electron recoil due to photon emission ever been confirmed by experiment? cause I can't find any reference to electron recoil being measured anywhere I look. If it has been measured, what methods do they use?

An electron rest mass in kilograms is calculated from the definition of the Rydberg constant R∞: where α is the fine structure constant and h is simply Plancks constant. Now, assuming the electron has an associated rest energy, Any idea on how this is calculated? I'm assuming using...

Homework Statement An electron is placed in an xy plane where the electric potential depends on x and y as shown in the figure (the potential does not depend on z). The scale of the vertical axes is set byVs = 500 V. In unit-vector notation, what is the electric force on the electron...

Hi, I'm new to the forum, and I am very sorry if this has been asked before. I am Japanese and therefore my English might be a little bit awkward. I want to ask about term symbols and if they can be used to derive electron configuration in lanthanides. First of all, I do not major in Physics...

Is the Abraham-Lorentz force (Also called radiation reaction force) the only recoil experienced by an accelerating charge? Say an electron is accelerating downwards, and that a photon emitted from this electron travels right, perpendicular to the direction of motion of the electron. Does the...

Homework Statement Neutrinos with energy of about ##1 GeV## are measured in an underground detector and compared with simulations of neutrinos produced in the atmosphere. Measured flux of upward going muon neutrinos ##(\nu_\mu + \bar \nu_\mu)## is half compared to simulations while measured...

Just wondering if there's a precise definition of what it means to be an elementary particle. I had assumed it was related to not being able to convert it into multiple "smaller" things, but then a photon is called elementary when it can be converted into smaller energy positrons and electrons.

Hello, At first, I wasn't sure why p-orbitals are shaped as they are. I looked through the posts of others here and it makes some sense now. My understanding is that they are dumbbell shaped because electrons repel from each other and are attracted by the nucleus. Then why is an s-orbital...

I want to ask one question, in physics, we calculated acceleration of electron in a conductor, but according to classical electrodynamics, any charged particle while accelerating looses energy through EM radiations, So does these electrons also emit radiation, if not then please tell me WHY?

This the answer that I have from Chalnoth in my other thread about nuclear fusion inside the sun (or star in main sequence). And after iron burning in the core of massive star, the star explodes and leaves a neutron star (or a black hole) behind. Is producing neutron in P+P reaction chains and...

Standard quantum mechanics text-books discusses Born rule, which states that the probability of finding a particle in a certain region in space is given by $$ |\Psi ({\bf r},t)|^2d^3r $$ Thing is, I never have seen a discussion about how you can actually measure the particle position in a...

Homework Statement Calculate the Q-value for the electron capture beta decay of Kr-81 (Answer in MeV, correct to 6 significant figures) Atomic Masses (amu) Kr-81 = 80.916592(3) Br-81 = 80.916291(3) proton 1.00727647 neutron 1.00866501 electron 0.0005485803...

Does the energy of the electron in a random hydrogen atom is in superposition of all eigenvalues(some value upon measurement) or you will find it most likely in the ground state. Additional clarification: From my reading the textbooks said the electron energy is in superposition, yet the...

What does trigger the phenomenon of an atomic electron losing energy through the issue of a photon? (I know how an atomic electron absorbs light and changes to a more energetic level but I never read an explanation cause-effect of the inverse)

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Hi there, I have a question about the definition of a charge of a free electron. Let's suppose that QED is the true theory of the interactions of charged particles. Presumably the charge on an (effectively) free electron, then, is the charge on an electron in which the electromagnetic...

Okay, I tried searching for this in the forums and didn't really find what I was looking for. So, I'll start a new thread and if anybody has seen this before, feel free to drop a link to an old thread or whatever. Many of our older space probes use/used thermoelectric radioisotope batteries to...

What are the number of states available to the electrons, and what is the difference between the ease of getting electrons to change states considered against the ease with which they change states by themselves? Can you give an example where they change states by themselves?

Hi there, I have a question about the rest mass of an electron. As we all know, the charge of an electron is a function of the energy at which the system is probed. When defining the charge, we typically use as our reference scale the charge measured in Thompson scattering at the orders of...

Just double checking this - I found this formula describing the radius of the path of an ion in a cyclotron: R = sqrt(2*E*m)/(e*B) .. where R is the radius in meters, E is the energy of the particle in joules, m is the mass in kilograms, c is the charge in coulombs, and B is the strength of...

Hopefully I have this right. When they discovered the electron, they immediately realized that the electron should get sucked into the nucleus due to the electromagnetic force from the opposite charges. Why didn't they assume that the electron could orbit the nucleus to cancel out the...

After calculating the force upon an electron and a force upon a proton in the atom of hydrogen, my result was a force of ≈8.2x10-8 Newtons acting upon the electron and proton each. If found this by using the formula Fe = (ke q1q2)/r2 Taking this number, I then applied it in the formula F = ma...

hello, how to derive the hamiltonian for a free electron in electromagnetic field mathematically ? for a first step what is the lagrangian for a free electron in the EM field in classical mechanics ? the physics textbook always like to give the results directly.

Homework Statement An electron moving with a speed v can behave as wave with wavelength 6.4 x 10^-15 m. Given that the mass of electron = 9.1 x 10^-31 kg and the charge of electron is 1.6 x 10^-19 C, find (a) the speed of v of the electron, and (b) the voltage needed to accelerate the electron...

Homework Statement (a) Find energies of states at ##(\frac{\pi}{a},0)##. (b) Find secular equation Homework EquationsThe Attempt at a Solution Part(a)[/B] In 1D, the secular equation for energy is: E = \epsilon_0 \pm \left| V(x,y) \right| When represented in complex notation, the potential...

According to Feynman's lecture in physics an electron doesn't fall on the proton because of the uncertainty principle. Now, if electron falls on the proton, it's position and momentum can be known so it leaves some place for it to move. But uncertainty principle is applicable for all particles...

Please tell me,why can't a photon transfer it's energy completely to a free electron?

Dear PF Forum, I have a question to ask. Supernovae produce neutron star (or Black Hole). This is what I summarize from wikipedia. 1. Is P + e = N? Is it that simple? Judging by its mass, altough slightly off. 2. Is Up Quark + e = Down Quark? Thanks for any answer

I understand that the interaction with the Higgs field (Higgs Bosons) confers mass to elementary particles such as the electron. Does that mean that interaction with an electromagnetic field (photons) confers charge to electrons? If not, what is the origin of charge? Also, how is it that the...

Hello Physics Peeps, It just came up in the notes for my electrodynamics class that an electrons charge squared can be expressed as the radius times the mass times the speed of light squared. e^2 = m_er_ec^2 I don't understand the motivation for doing this. I've tried to search for other...

Homework Statement Homework Equations $$ \psi_{100} = \frac {1}{\sqrt{\pi a^{3}}} e^{-r/a} $$ The Attempt at a Solution a) $$\langle r \rangle = \frac {1}{\pi a^{3}} \int_0^{2 \pi} d \phi \int_{0}^\pi d \theta \int_0^{\infty} r^{3} e^{-2r/a} dr$$ This comes out to be ##\frac {3}{2}a##...

Hi, Einstein once showed that if we assume elementary particles to be singularities in spacetime (e.g. black hole electrons), then it is unnecessary to postulate geodesic motion, which in standard GR has to be introduced somewhat inelegantly by the geodesic equation. I don't have access to...

This relates to a question I asked recently on Quantum Dots, but I'll rephrase it and hopefully any chemists out there can help. If we have (n,l) = (1,2) where n and l are quantum numbers can we determine the orbitals? and hence the number of electrons in a quantum dot? i.e. And also I've...

Homework Statement What is the velocity of a beam of electrons that go undeflected when passing through crossed electric and magnetic fields of magnitude 6.8 kV/m and 4.9 mT, respectively? What would be the radius of the electron's orbit if the electric field were turned off? Homework...

what is the background force for the motion of electron? is any other sub atomic particle can move? if no why?

Hi, Assuming the electron is a sphere of finite extent, the classical electron radius is derived by equating the energy of the electric field with mec2. For the computation of the field energy, we have to assume a charge distribution. Both constant charge density and constant surface density...

If I run a current through a wire with a 90 degree turn, what prevents the electrons from continuing out of the wire is a straight forward path? What force accelerates them in the direction of the wire?

I just need a simple confermation, when the outermost shells of an atom have unpaired electrons is it the pairing of electrons between two different atoms say oxygen and two hydrogens that causes them to bond together? I keep going back to counting subshells and their spins? my mind went...