The coulomb (symbol: C) is the International System of Units (SI) unit of electric charge. Under the 2019 redefinition of the SI base units, which took effect on 20 May 2019, the coulomb is exactly 1/(1.602176634×10−19) elementary charges. The same number of electrons has the same magnitude but opposite sign of charge, that is, a charge of −1 C.
Hi!
Why coulomb is not a base unit in Physics, but the Ampere is (and ampere is coulomb/s)?
Isn't it like saying that m/s is a base unit?
Can someone explain it to me?
Let us consider relativistic particle (electron) which moves with relativistic speed ##v## in the Coulomb field (in the field of a fixed heavy nucleus). The main question is what is the potential energy of a particle in such a static field? Landau and Lifshitz in their book "Field Theory"...
I have derived the Coulombian potential as an effective potential between two spinless charged particle taking the non-relativitic approach on the scattering amplitude obtained in terms of the Feynman rules in SQED.
The scattering amplitudes are:
I'm using the gauge in which xi = 1.
How could...
Suppose you have a sphere of radius a of positive charge, and a concentric shell from a to b of negative charge. The positive charge is equal to the negative charge. (non-conducting, uniform density)
Is there an outward pressure at a of kqq/a2/(4πa2) - with pressure decreasing with radius...
I'm studying nuclear physics in a text, but at one point that is said: "Both the Coulomb potential that binds the atom and the resulting electronic charge distribution extends to infinity" , I don't understand what is that "resulting electronic charge distribution extends to infinity" what they...
I tried just calculating the force with Coulomb's law, then calculating the forces for each vector individually and adding, but I got it wrong both ways
I am struggling over a problem and i could really use some help in this.
So it's about finding phase shifts in a localized sphere of coulomb and harmonic potential. I tried solving the radial Schrodinger equation for both of them by using power series method, but still i am having problem...
I actually found most of it out I'm just struggling with how to find the mass of the balls. I'm not sure how you would do that since could only derive two equations from the information given or are we assuming the mass is so small that it doesn't matter?
Q = charge of one pith ball
d =...
Moderator's note: This thread is a spin-off of
https://www.physicsforums.com/threads/what-are-the-most-important-open-questions-in-classical-physics.983671/
R. de Sangro, G. Finocchiaro, P. Patteri, M. Piccolo, G. Pizzella, "Measuring propagation speed of Coulomb fields", Eur. Phys. J. C 75...
I am reading "Coulomb and the evolution of physics and engineering in eighteenth-century France". There it is said in page 152 para 1 that "Coulomb found that within a very wide range, the torsion device oscillated in SHM".
My questions are:
(1) By just looking at the time period of the...
Summary: I'm looking for a table of Coulomb and exchange integrals for Lithium and beyond.
I'm looking for a convenient table of Coulomb and exchange integrals for Lithium and beyond. I've looked everywhere and I find integrals for J,K 1s, 2s or 1s,2p for Helium. Does anyone know of a...
The only thing tripping me up here is that the answer needs to be in vector form. If the question was asking for the scalar form, then I would just find the distance between the charges (plot the charges according to their vector coordinates, then use pythagorean theorem to find the distance...
In a bound state like atom nucleus (except H-1), protons carry a positive charge so repel each other by the Coulomb force. This type of electromagnetic force, (also referred to as electrostatic repulsion) is an inverse-square force (has infinite range characteristics), so a proton added to a...
Let's say a rocket carrying a positively charged balloon starts to accelerate with a constant proper acceleration at time t.
After a long time another rocket carrying a positively charged balloon is launched. The crew of this rocket drives the rocket to a position right below the...
Can charges collapse under coulomb attraction like charge-less matter does under gravity? In a way it's similar to asking about the lower limit of coulomb force if there is any. Also, does Pauli exclusion principle save the day just as in the case of gravity?
Homework Statement
Consider a configuration consisting one +q charge ( upper right) and three −q charges, arranged in a square.
Side lengths = d.
Calculate the total F force vector acting on charge +q.Homework Equations
Vector form of culomb’s force
F=( kq1q2/r^2) rhat
(rhat for unit...
Homework Statement
A solid isolated sphere with radius R has a non uniform charge which is given by ρ= Ar²,
with A a constant and r<R measured from the centre of the sphereHomework Equations
(a) Show that the electric field outside the sphere is equal to E = (AR5)/(5ε0r²)
(b) Show that the...
Hello, I am reading a section in Jackson discussing classical Rutherford scattering, and he mentions incorporating a cutoff in the Coulomb interaction in order to model electric screening. I am trying to understand how he applies this, as described below.
The set up is basically the classic...
Homework Statement
Suppose we have a regular n-gon with identical charges at each vertex. What force would a charge ##Q## at the centre feel? What would the force on the charge ##Q## be if one of the charges at the vertices were removed? [/B]Homework Equations
Principle of Superposition, the...
I don't really know how to fit what i want to this template, but i'll try.
The thing is that i wonder if anyone can explain to me step-by-step what happened in this solution, because i don't really understand it.
Homework Statement
There are two balls. Upper one(mass m, charge Q) hung on a...
Homework Statement
Suppose an object has a charge of 1 C and gains #9.38 ✕ 10^18# electrons. When another object is brought in contact with the first object (after it gains the electrons), the resulting charge on the the second object is 0.9 C. What was the initial charge (in Coulombs)...
Hi everyone,
I've been reading about the Klein Gordon equation with the Coulomb Potential. The full solution can be found here:
http://wiki.physics.fsu.edu/wiki/index.php/Klein-Gordon_equation#Klein-Gordon_equation_with_Coulomb_potential
I'm confused near the beginning of this. I understand...
Homework Statement
Two pith balls each have a mass of 1.0g and equal charges. One pith ball is hung from an insulating thread. The other is fixed at a horizontal distance of 3.0cm from the first, The first hangs at an angle of 30.0° from the vertical. Find:
a) the gravitational force on the...
I wrote and solved this problem but am having serious doubts about the answer I obtained.
Homework Statement
Two point charges \pm q move along the z-axis with velocity \pm v. If they are at the origin when t=0, what is the electric field magnitude a distance r from the z-axis?
Homework...
Homework Statement
Q1<------>Q2<------>Q3
In the above figure, the distance between Q1 and Q2 is equal to the distance between Q2 and Q3. That distance is R=1.5 m.
Q1= 2.24x10-6 C, Q2=+Q1 and Q3=-Q1.
Calculate the total force on Q1. Give your answer with a positive number for a force...
regards my question is how each coulomb of charge can lose (transfer ) energy when going from a to b when electrons are very slow
the definition of potential difference: is how much each coulomb of the charge loses (transfer ) energy when going from a to b
an example to clarify the question...
Homework Statement
How to calculate the Coulomb barrier between a proton and a lithium nucleus. The variable is r (interaction radius). The known data is Z1, Z2, k (Coulomb constant), and e (elementary charge).
Homework Equations
The equation is UCoul = kZ1Z2e2/r
The Attempt at a Solution
I...
Homework Statement
Two point charges q and 4q are located at r1 and r2, respectively, on the xy- plane. The magnitude Q and location R of a third charge to be places on the plane such that the total force on each of the three charges vanishes, are?
first i plotted the problem on the xy...
Homework Statement
For a positively-charged particle at the origin, and a negatively-charged particle lying to its right on the positive x-axis, the electrostatic force on the negative charge is attractive, and Coulomb's Law gives the magnitude of that force:
F = k |Q1| |Q2| / x^2
k is...
For a proton striking an atomic nucleus (in a Cockcroft-Walton accelerator, for example), the Coulomb barrier must be overcome. The calculation of the Coulomb barrier is U = k Z1Z2 e2 / r
r is interaction radius. How can I find that? For a proton to enter the atomic nucleus what would it be?
Homework Statement
Four protons (each with mass 1.7 10-27 kg and charge 1.6 10-19 C) are initially held at the corners of a square that is 7.1 10-9 m on a side. They are then released from rest. What is the speed of each proton when the protons are very far apart? (You may assume that the...
In a heavy nucleus, the balance of the Coulomb and nuclear forces is a delicate one. This can be seen in two cases: First, in oblong deformed nuclei, alpha particle emission is more likely to occur at the poles, where the Coulomb barrier is thinner, than at the waist. Second, heavy synthetic...
My aim is to derive the photon propagator in an Coulomb gauge following Pokorski's book method.
In this book the photon propagator in Lorenz gauge was obtained as follows:
1. Lorenz gauge: ##\partial_{\mu}A^{\mu}=0##
2. It's proved that ##\delta_{\mu}A^{\mu}_T=0##, where...
My aim is to derive the photon propagator in an Coulomb gauge following Pokorski's book method.
In this book the photon propagator in Lorenz gauge was obtained as follows:
Lorenz gauge: ##\partial_{\mu}A^{\mu}=0##
It's proved that ##\delta_{\mu}A^{\mu}_T=0##, where...
Hi,
I have learned that, in a nuclear fission or an alpha decay, the available energy released is the difference of masses between the initial nuclide (+ eventually some other initial particles) and the output particles, times c^2 (as E = mc^2).
I'm fine with that. But I wonder : what about...
From Painleve we know that Coulomb's law of friction being applied to rigid bodies systems may produce contradictions. Painleve constructed several examples of such contradictions, so called Painleve's paradoxes, see [Painleve P. Leçons sur le frottement. P.: Hermann, 1895]. Those examples...
Hi, I'm no expert in math so I'm struggling with solving these integrals, I believe there's an analytical solution (maybe in http://www.hfa1.physics.msstate.edu/046.pdf).
$$V_{1234}=\int_{x=0}^{\infty}\int_{y=0}^{\infty}d^3\pmb{x}d^3\pmb{y}\...
Homework Statement
An electron in the Coulomb Field of the proton is in the state:
|ψ> = (4/5)|1, 0, 0> + (3i/5)|2, 1, 1> with |n, l, m> as the quantum numbers defining the state
a) What is <E> for this state? What are <L2> and <Lz>?
b) What is |ψ(t)>? Which expectation values...
Hi everyone!
I am trying to create a crude electron-hopping model to study conductivity in a biological wire composed of discrete sites. The model is pretty simple: imagine a line composed of sites. Electrons can hop from site to site with probabilities that depend on the free energy difference...
I'm looking at Aitchison and Hey's QFT book, trying to verify Eq. 8.27 (which is in fact problem 8.2). It asks us to verify that the matrix element for the scattering of a charged spin zero particle (s^+) is
<s^+,p'|j^\mu_{em,s}|s^+,p> = e(p+p')^\mu e^{-i(p-p')\cdot x}
where...
Hi.
Say a positive charge is at (x,y,z)=(0,0,0) at t<0 then (1,0,0) at t>0.
Electric field at (x,y,z)=(l,0,0) is (a,0,0) at t<l/c then (b,0,0) at t>l/c thus a<b.
With time delay of l/c, what propagates from (x,y,z)=(0,0,0) to (l,0,0) ?
I do not think it is electromagnetic wave because it is...
Homework Statement
[/B]
Find the electric force between the two spheres.
Sphere r=b-a has a volumetric density of p=K, where K is a constant
Sphere r=a has a volumetric density of p=θ*r
Homework Equations
As you can see the sphere of radius 'a' doesn't have a uniform electric field because...
The common presentation for free field quantization proceeds with the Lorentz and Coulomb (##\phi = 0, \,\nabla \cdot \mathbf{A} = 0 ##) constraints. Then ##A## can be defined
$$\mathbf{A} \propto \iint \frac{d^3 p}{\sqrt{2\omega_p}}\sum_{\lambda} \Big(e^{i\mathbf{p}\cdot...
Homework Statement
A positive point charge Q_1 (4.0 µC) and a negative point charge Q_2 are placed near each other. When a negative charge Q is placed in the middle between the two point charges, the magnitude of the resultant forces on Q_1 and Q_2 doubles. What is the charge of Q?
(answer...
As I understand Coulomb potential associated with charged particle is described classically.
My question is if there is a way how to describe Coulomb potential of charged particle that is in quantum superposition of being "here" and "there"?
My motivation for question is that I am trying to...
ok, so i am taking an auto electrical class this semester and i can not continue reading the book/doing the homework until i understand this..my question is this: if andré marie ampére (1775-1836) discovered the electron flow, how the hell did he do it back then? how did they discover atoms and...
Can you gurus help me understand in a qualitative way the nature of the Coulomb barrier as it applies to alpha decay? I can intuitively appreciate the Coulomb barrier as it applies to anincoming charged particle, but resources I have been reading apply the same term to the barrier felt by...
Dear all,
In my quantum mechanics book it is stated that the Fourier transform of the Coulomb potential
$$\frac{e^2}{4\pi\epsilon_0 r}$$
results in
$$\frac{e^2}{\epsilon_0 q^2}$$
Where ##r## is the distance between the electrons and ##q## is the difference in wave vectors.
What confuses me...
Hello everyone
Homework Statement
I have been given the testfunction \phi(\alpha, r)=\sqrt{(\frac{\alpha^3}{\pi})}exp(-\alpha r) , and the potential V(r,\theta, \phi)=V(r)=-\frac{e^2}{r}exp(\frac{-r}{a})
Given that I have to write down the hamiltonian (in spherical coordinates I assume), and...