Electrons Definition and 998 Threads

Time indepedendent Schrödinger equation for a system (atom or molecule) consisting of N electrons can be written as (with applying Born - Oppenheimer approximation): $$ [(\sum_{i=1}^N - \frac {h^2} {2m} \nabla _i ^2) + \sum_{i=1}^N V(r_i) + \sum_{i < j}^N U(r_i,r_j)] \Psi = E \Psi $$ Terms in...

In this thread, @haruspex presented a very deliberate point about the role of electrons in a nuclear fission reaction (he might have said or meant something else but I will present my version of it). The problem that we have before us can be stated, as candidly as my linguistic faculty of mind...

If I switch off the anode voltage in a teltron tube (used to determine the charge-to-mass-ratio of the electron), the visible electron beam disappears. Why is this so? The electrons, which were already shot out of the electron gun before, have a high velocity and should continue to move on a...

I have held the assumption that batteries supply electrons at the negative terminal and absorb electrons at the positive end for many years. However, after watching this video at about 3:30, it is said that batteries do not actually supply charged particles but that the battery only creates an...

Hello, I would like to discuss with my students the deflection of electrons in electric and magnetic fields. For this purpose, I would like to perform the experiments with electron beam deflection tubes and teltron tubes. How would you implement this organizationally in the classroom? There are...

Can someone please explain the four classes of fundamental particles? (Just the basics) I came here because I never learned any chem or physics in school so please explain like I’m five :)

My understanding is that the repulsion between two electrons is mediated by the exchange of virtual photons – virtual meaning not lasting long enough to be detected. But suppose one of the electrons is in the sun and the other on Earth. There should still be a repulsion because the...

My book says that emission spectra are produced when an electron in excited state jump from excited to lower energy states. It also states that solids and liquids produce continuous spectra and it depends upon temperature only (is this black body radiation?). I know, Electrons around a nucleus...

The video on youtube on the above link seems to imply that electrons don't flow through a circuit. At 01:29 into the video, the narrator says that he used to teach his classes how electrons move through a circuit by using a clear plastic tube with a chain inside of the clear plastic tube. The...

I'm just confused on whether not all electrons are identical and if they are, how they are.

Hi Pfs. I think that QM can explain the classical things explained by classical physics. Using mean values and so on. We know that in a constant magnetic field an electron will rotate on a circle (at the macroscopic scale approximation) I have the answer for the Larmor precession but how to...

In the following pdf I tried to calculate the density of states of free electrons and phonons. First, I found the free electron DOS in 1D, it turns to be proportional to (energy)^(-1/2) and in 2D it is constant. However, I am not sure I found the DOS for phonons in the second part of the...

Hi, All cosmological models with a non-zero cosmological constant will approach a de Sitter universe in the far future. In theory this can means that the most basic group of particle physics should be the de Sitter rather than Poincaré. Mass is a Casmir operator of the Poincare but not of the...

a) My idea is: 1. Find the energy created by annihilation process, which is ##E=2mc^2## where m is the mass of electron 2. Find the wavelength of photon by using formula E = hf 3. Find the speed of positron by using the formula of de broglie wavelength 4. Find the p.d by using conservation of...

If you could command all the electrons in an average human body and get them to spin in synchronicity (a clockwise circle in the horizontal plane) how much magnetic force does that produce? Would it create a force against gravity and make you feel lighter? How much lighter?

Preface: I am new to physics and am trying to learn on my own, though I hope to take a class soon. I looked for a forum for beginners but didn't see one, but this seemed to be the closest forum. So I hope I can get some help with my question here. If it is the wrong forum, feel free to...

Most articles said electrons, quarks and gluons are indivisible thus have no compositions unlike the other particles. So, does that means electrons, quarks and gluons are composed of nothing and these elementary particles are indeed 100% void?

I'm curious whether the scientists actually show the real electron in this video. Thoughts?

I am not sure if the explanation below is enough. This is a high school level question. When rubbing occurs between glass and silk, then heat energy is produced which provides the energy needed to free up electrons in outermost orbits of atoms in silk or glass. But silk has very tightly bound...

Atoms bond because compounds are more stable or have less energy than individual atoms. Interatomic potential energy depends with distance of atoms and there is a distance at which potential energy has minimum. This distance is a length of the bond. When forming covalent bonds, why is it...

I'm trying to figure out why emission nebulae glow. I read various sites such as a NASA website explaining why they shine; 'The massive stars embedded within the nebula give off enormous amounts of ultraviolet radiation, ionizing the gas and causing it to shine.' The Britanica article on...

From: https://opentextbc.ca/universityphysicsv3openstax/chapter/photoelectric-effect/ "The photoelectric effect has three important characteristics that cannot be explained by classical physics: (1) the absence of a lag time, (2) the independence of the kinetic energy of photoelectrons on the...

I take a conductor and expose one side to a nearby region of negative charge. The metal's free electrons are repelled, and many collect at the opposite side to the charged region. High School stuff. Okay, so now I accelerate the metal in one direction. What happens to the free electrons...do...

Homework Statement:: Ionised atom, free electron, conduction band, donor energy level and acceptor energy level Relevant Equations:: None I have some confusion about the concept of some electronic bands and energy levels. Beyond valance band, in a solid crystal lattice, For an atom, can...

Existence of an universal problem solver, a polynomial-time NP-complete algorithm is a $1000000 prize question. But suppose that we were able to know something "simple", e.g. an electron state or electron wave function exactly. Would we be able to solve complex mathematical problems (like...

I would hope something like this would come in handy: ΔEΔt>h/2π. Mainly because it seems relatively simple, although I'm not really sure what the inequality really means, other than there is a certain uncertainty associated with that pair. But there are some things that really muddy the waters...

What changes occur in electron, whenit through in a electric field

I am a new to this and I try to understand the basics. So initially once the atoms of silicon come together to form a solid, due to Pauli law no electrons can exist in the same energy state,thus many energy states are formed which together make the bands. My problem starts at this stage where I...

When various atoms are turned into BEC's, are their electrons still arranged in their standard atomic orbitals like at higher temperatures? Or are the electrons free floating around the entire condensate? If the electrons are free-floating, then are they arranging themselves into superconductive...

So if particles such as the electrons when "measured" forsake their probabilistic wave form and manifest into a definite particle form, does that mean for all intent and purpose the electrons of every objects we observe are already collapsed? If that's the case how did the labs get pre-collapse...

I am currently studying Electrical Engineering and I have this question: An energy band is formed by the overlapping of atomic orbitals of atoms coming close to each other.I suspect that if the energy of the atomic orbital of the valence electrons of a chemical element is less than the energy of...

Hello everyone! I've tried everything but the equation (3) in "Deflection of electrons in electrostatic field" is impossible. Can someone at least hint me to a a way the composed it ?

Spectral response : ##\lambda=\frac{1.24} {E_G}## ->eq(1) Given, ##\lambda = 2537 * 10^{-10} m = 0.2537\mu m ## ##E_G = \frac{1.24} {\lambda} = \frac{1.24} {0.2537} = 4.88 eV## So, i can assume if 10,000 photons illuminate then 10000 electrons will be emitted. But i am mainly confused with the...

I suppose the stream isn't being charged!

The required number of free electrons to be calculated is ##n = \frac{dv} {AM} = \frac{A_0dv*10^3} {A} ## I know mass of single atom is ##M## The atomic weight of mole of atoms is ##A##. Hence ##A = A_0*M ## ##d = \frac{A} {1} ## -> "1" represents ##1m^3##. I am confused how to proceed further...

Hi, Could you please help me with the queries below? Thanks in advance! Question 1: I was watching this video. Between 8:36 to 9:44 the following is said: "But only firing particle by single particle at this barrier with the 2 openings and by recording dot by single dot where each of those...

Lets say, in zero gravity space, you have an incredibly precise collider that slams protons and electrons into each other as perfectly as possible such that all momentum is canceled out and the resulting neutron has no velocity relative to the observer. As protons and electrons continue to...

Hello , Why does an incoming photon can only scatter from an electron if the electron is not bound top an atom ? Because from what I know a bound electron can absorb a photon then be excited to a higher energy level and then re-emit a photon while transitioning back to it's previous energy...

I've written a calculator that computes the number of conduction electrons in a segment of wire with a specific gauge. For a 1 ft segment of 24awg copper wire, this is what it prints out. AWG [0 - 36]? 24 Wire length (mm) (0 - inf)? 304.8 AWG 24 radius: 0.255 mm dia: 0.511 mm area...

Whether in vacuum inside a CRT, or in a metal, a potential difference has to be applied for free electrons to move from the negative to the positive terminal. However, the reality is that free electrons are still moving when no voltage is present at the 2 ends of a metal conductor. In this...

So I know current is just coulombs/second. Electrons are also in the unit of coulombs, so I can get coulombs to cancel. 7.9C/s/1.602E-29C = 4.93133E29 1/s Now I just need to get mol on top. There are 6.022E23 electron in a mol so 4.93133E29 1/s / 6.022E23 atoms/mol = 8.1889E5 mol/s. Now my...

In a conductor, excess charge resides on the surface. That seems odd, because one would think that the overall energy of the system could be lowered by allowing some of the excess charge to move inward and away from all the charge on the surface, but obviously that can't be true, because charge...

I have to give a presentation about natural Radiation and I am very happy about it because it includes Astrophysics. I want to explain to my audience how the stars produce cosmic rays. I thought about explaining to them how nuclear fusion and that kind of stuff works but then I realized that I...

Hi everyone, I have to solve this homework without having any books where to find the theroical topic or examples, so if you could help me find materials that I can use to understand or you want to try help me understand how to get the solution would be very helpfull. I don't have enough time to...

Hello, I have this question whether it will be possible to generate electricity by heating up a suitable metal (conductor). We know from the photoelectric effect that high energy photons (of visible light; probably with frequency closer to that of violet) can knock off the outer electrons from...

How many electrons can you remove from a solid substance before it breaks down at a chemical level? Thinking this through myself, you can create positively or negatively charged objects to a degree, especially with a metallic conductor that can tolerate a loss of charge at the cost of the...

Can you compare the energy loss of electrons and protons due to the radiation they emit? In fact, I want to know which of the two loses more energy when it emits radiation.

I have two charged spheres connected to different ends of an infinitely long conductor. The first sphere has positive charge, another sphere has negative charge. Suppose that the electric field of the first sphere at point A is zero, and the electric field of the second sphere is zero at point...

I have a positively charged sphere that is connected with a conductor to a negatively charged sphere. Positively charged sphere will take electrons from conductor. Then the end of conductor expierences lack of electrons and take them from the nearest atoms of conductor. When it gets to the other...

I am reading a book on fusion and just went over a paragraph of magnetic mirror confinement. What I want to understand is this. So all charged particles gyrate around magnetic field lines and if they have also a velocity parallel to the field they form helical paths. The gyroradius is...