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How to avoid the ordinary Coulomb solution in QCD?

First, I think your proposed current would break gauge invariance, but that's a relatively trivial problem in that I think you could reformulate your question getting around that issue. The bigger ...
Andrew's user avatar
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Electric field experienced by a charge

What we measure (with a load cell for example) is the force on charge 2. And we can test that $F \propto \frac{Q_1Q_2}{r^2}$. Then we define the electric field in the location where $Q_2$ are as: $E = ...
Claudio Saspinski's user avatar
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Find Velocities When Distance is Minimal - Electrostatics

Calculation of Velocities using Conservation of Energy and Momentum At r = 0.4 m: $U_{p_{0.4}} = \frac{k \cdot q_A \cdot q_B}{r_A} = \frac{(9 \times 10^9) \cdot (400 \times 10^{-9}) \cdot (900 \times ...
David's user avatar
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1 vote

Electric field at a point due to dielectric inserted in between a parallel plate capacitor

The induced charges on the dielectric will attract the charges on the plates. Since the dielectric is inserted partially between the two plates, the charge on the plate near the dielectric will ...
BaddDadd's user avatar
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1 vote

Electric field at a point due to dielectric inserted in between a parallel plate capacitor

Consider the situation before the dielectric was introduced (left diagram) and after the dielectric was introduced (right diagram). There are two possible scenarios. The first is when the capacitor ...
Farcher's user avatar
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Electric field at a point due to dielectric inserted in between a parallel plate capacitor

Let me ask , what is Electric field due to a single plate of charge of density $\sigma$ ? It's : $$E_{single}= \frac{\sigma}{2\epsilon_0}$$ Even though there is polarization of the dielectric , but ...
CP of Physics 's user avatar
1 vote

Will the electrical potential difference between the Windward and Leeward sides of a mountain range generate electrical current?

It is possible that a current could develop in your cable, but it won't be a steady current like you'd want to charge a battery. Humans have actually built quite a lot of conductors that stick into ...
anon's user avatar
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0 votes

Understanding Symmetries and Invariances in Electrostatic Fields

The concept of symmetry plays an important role in all branches of Physics, and electrostatics is a good playground for developing an intuition on how symmetries works. A little disclaimer: I do not ...
Giovanbattista Favorito's user avatar
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Why are fields described as force divided by mass or charge?

You are right in demanding a clear answer for this issue (in school, the teacher either can't answer or can't explain the thing). What is the difference between physics and philosophy if we are not ...
Andreas Klein's user avatar
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How will the capacitance of a capacitor reduce when the distance between the plates is increased?

I know that we can prove capacitance is indirectly proportional to distance by the formula $C=\epsilon A/d$, but I am not understanding how the relationship between $C$ and $d$ came in place. ...
Bob D's user avatar
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Electric dipole

To understand it intuitively I suggest that do not think of an ideal dipole, $\mathbf p$ as having zero length with infinite charges at its ends but rather in your mind visualize it as something ...
hyportnex's user avatar
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Electric dipole

Because that's how "Electric field" is defined. Specifically, ' its direction ' is defined as the direction in which force would act upon a positive charge placed at that particular point ...
CP of Physics 's user avatar
2 votes
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Electric dipole

Charge is a scalar and field is a vector. $\vec{E}$ and $-\vec{E}$ are going to have different directions (multiplication of a vector by -1 changes it's direction.) Since the equation for the electric ...
mike1994's user avatar
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Field induced outside a grounded 2D circle conductor by an exterior point charge. A puzzle, not what you think!

Not all puzzles have a solution. Your hidden assumption is that there always should be a solution with the object's surface at the same potential as infinity, a situation we then define as "...
Jos Bergervoet's user avatar
0 votes

How will the capacitance of a capacitor reduce when the distance between the plates is increased?

Physically, the Capacitance of the plates at a position is the magnitude of charge given to the plates to maintain a potential difference of 1 Volt. If the distance between the plates increases, the ...
Piyush Lath's user avatar
0 votes

How will the capacitance of a capacitor reduce when the distance between the plates is increased?

Consider a charged, insulated capacitor. One plate carries Q1=Q and the other Q2=-Q. If you increase the distance between the plates you are increasing the distance between Q1 and Q1. This will ...
my2cts's user avatar
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How will the capacitance of a capacitor reduce when the distance between the plates is increased?

Consider a capacitor with capacitance $C$ which has a charge $Q$ when the potential difference is $V$ and $Q=CV$. Now assume a second identical capacitor with charge $Q$ and potential difference $V$. ...
Farcher's user avatar
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0 votes

How will the capacitance of a capacitor reduce when the distance between the plates is increased?

"I know that if the potential difference between the plates increase that capacitance will reduce" This is not generally true... Capacitance is defined as $C=\tfrac QV$ in which $Q$ is the ...
Philip Wood's user avatar
1 vote

How will the capacitance of a capacitor reduce when the distance between the plates is increased?

Now I know that if the potential difference between the plates increase that capacitance will reduce Ideally, this is not the case. Capacitance depends on the geometry of the conductors, not the ...
BioPhysicist's user avatar
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Maxwell stress tensor on a capacitor late given a dielectric

I figured out the answer to my question! Although I couldn't find any reference to the Maxwell stress tensor in a dielectric in my normal Griffiths textbook, I found that "Electrodynamics of ...
asyndeton256's user avatar
1 vote
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Electrostatic potential outside of a charged ball

Starting from the general form of the electrostatic equations $$\begin{align}\mathbf{\nabla} \times\mathbf{E}(\mathbf{r})&=0 \tag{1} \label{1}, \\[5pt] \mathbf{\nabla} \cdot\mathbf{E}(\mathbf{r})&...
Hyperon's user avatar
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0 votes

Will a piezoelectric material under constant pressure maintain its electrostatic charge/behave like an electret?

The piezoelectric material has a tiny, tiny bit of electric conductivity, which will dissipate the charge buildup over time. In addition, the air surrounding the piezoelectric slab is also very very ...
niels nielsen's user avatar
2 votes
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Does the geometric shape of the cross-section of an infinitesimally thin conducting charged thread (wire) affect its electric field?

I assume the charge is uniformly distributed around the major radius for all these tori. You are right. Shape and conductivity make smaller and smaller differences as a torus approaches a thin ring. ...
mmesser314's user avatar
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0 votes

How does this proof of Gauss’ law generalize from $1$ to $n$ charges?

I don't see a problem with the charges being off center. He is not using a gaussian surface in which E is a constant. He is not attempting to calculate the electric field, but rather the total flux by ...
Pato Galmarini's user avatar
1 vote

Voltage: work to move a charge, or difference of electric potential?

In the diagram below the red dashed circle with the negative charge at its centre is an equipotential with the electric field lines produced by the negative charge at right angles to the circle. As ...
Farcher's user avatar
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Comparing Electric Potential Energy of two Charges

From your picture the potential has by approximation left-right symmetry and top-down antisymmetry. Therefore the potential difference V_A'-V_A=V_B'-V_B. If the charges are equal then the ...
my2cts's user avatar
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Comparing Electric Potential Energy of two Charges

The change in electric potential energy for a positive charge going from position $A$ to position $A'$ is the same as the change in electric potential energy for a positive charge going from position $...
Farcher's user avatar
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Comparing Electric Potential Energy of two Charges

You can calculate the energy of the charges explicitly. For simplicity, let us reduce the problem to a one-dimensional case. Take fixed charges $-Q$ at $z=-a/2$ and $+Q$ at $z=a/2$. These act as the ...
CompassBearer's user avatar
1 vote

Comparing Electric Potential Energy of two Charges

In the case that A and B both have the same positive charge: remember that potential energy associated with a position (it is not defined as something that requires two positions e.g. A and A') is the ...
Marius Ladegård Meyer's user avatar
1 vote
Accepted

Voltage: work to move a charge, or difference of electric potential?

it will take work to move the positive charge from point A to point B, as I must counteract the vertical component of the electric force and so on. You are quite correct that the distance to the ...
John Rennie's user avatar
0 votes

Charge besides conductor

Suppose the sphere has radius $R$ and we have a point charge $+q$ at distance $D$ from the sphere's center. Then the Induced charge distribution on the sphere's surface will give exactly the same ...
Jos Bergervoet's user avatar
0 votes

Why does the graph of the electric potential of a conducting sphere look like this?

Graphs for kQ/r and $kQ/r^2$ are different.In textbooks it is not very easy to distinguished these graphs.We can put the positive and negative values of r and find that kQ/r will be positive for ...
Muskan's user avatar
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Charge besides conductor

If a positive charge is near (but not touching) the sphere it will not create a net charge on the sphere. It will only redistribute the existing charge on the sphere so that the negative charge (of ...
Bob D's user avatar
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1 vote

Charge besides conductor

The positive charge produces an electric field which if nothing happened on the adjacent conductor would pass through the conductor. However the induced charges on the conductor also produce an ...
Farcher's user avatar
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2 votes
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When Can a Set of Surfaces Be Equipotentials?

Because it could be a function of the position variables over the surface of $F$, which would mean that it is not in fact an equipotential.
mike1994's user avatar
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1 vote
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How can I deduce a capacitance of a capacitor without existing formulaes?

Since you are assuming $k$ is a constant, you can take it outside of your integral formula to give $V(t) = k \int_0^t r \space dt$ But $\int_0^t r \space dt$ is the charge $Q(t)$ that has accumulated ...
gandalf61's user avatar
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1 vote
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How do conductors actually work in electrostatics?

There are different kinds of conductors. The common thing is charges are free to move around. Metals are a common example. In a metal, some electrons do not stay in orbitals around individual atoms. ...
mmesser314's user avatar
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0 votes

Self-Energy of a Conducting Shell based on Surface Charge Distribution

If the shell is conducting, it cannot have charge separation on inner and outer surfaces. This is possible, however, for a non-conducting shell. In this case, the total energy still remains $kq^2/2r$, ...
CompassBearer's user avatar
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Maxwell stress tensor on a capacitor late given a dielectric

$E_{zz}= \varepsilon_r$V/d so that's where the relative permittivity is hiding. The Feynman lectures may be helpful.
Spehro Pefhany's user avatar
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I don't understand Green's derivation of the Laplace/Poisson equation inside an electrically charged body

I calculate the potential at a point with position $\vec{r} = b \hat{z}$ at distance $b$ from the center of a sphere with radius $a>b$, with the origin at the center of the sphere. \begin{align} V ...
d_b's user avatar
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0 votes

How do I compute the voltage accross a cell membrane given microstate of neuron (distribution of charged ions)?

As always in thermodynamics, the voltage (potential energy/charge) across a boundary between two differently charged fluids is the difference of the chemical potential per particle times the ...
Roland F's user avatar
2 votes
Accepted

How do I compute the voltage accross a cell membrane given microstate of neuron (distribution of charged ions)?

The typical textbook start is the Nernst equation, which gives the reversal potential for a ion species. That is, is the electric potential that balances a given concentration gradient: $$E_{rev}=\...
Anders Sandberg's user avatar
0 votes

Does cutting out the surfaces with no surface charge affect the charge distribution on the remaining parts of a conducting surface of arbitrary shape?

Actually, I doubt that there can be zero charge density areas of a charged conducting surface (at least if the surface is connected): if there were such an area, why wouldn't the charge get ...
akhmeteli's user avatar
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3 votes
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Does cutting out the surfaces with no surface charge affect the charge distribution on the remaining parts of a conducting surface of arbitrary shape?

Removing the uncharged parts of a charge distribution would not change the field configuration elsewhere. To show this, start with the Poisson equation (assuming the permittivity $\epsilon_0$ is the ...
CompassBearer's user avatar
0 votes

Moving charge to define magnetic field

1 - A particle doesn't have to be in motion to define a magnetic field. A stationary particle will just create a null magnetic field (see Biot-Savart law). 2 - No. See Lorentz's force $\vec{F} = q\vec{...
Gabriel Ybarra Marcaida's user avatar
1 vote

$z$-component of electric field due to a static square loop

The electric field at a point P located at a distance $z$ above the center of a square, due to only one side of the loop is given by, \begin{equation} \mathbf{E}(P)=\frac{\lambda}{4\pi\epsilon_0}\int_{...
MauvaiseFoi's user avatar
0 votes

$z$-component of electric field due to a static square loop

Your reasoning about the variation of θ along the side is correct, but due to symmetry and the integral approach, the effective cosθ is taken at the midpoint for simplification. The integral approach ...
Ernesto Heine's user avatar
0 votes

Using an imaginary conducting shell of infinite radius to calculate capacitance of a spherical conductor

If I got your question right, that's because the electric charge in the inner sphere accumulates in the surface layer, and thus it's (approximately?) equivalent to a thin shell. In this spherical ...
basics's user avatar
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$z$-component of electric field due to a static square loop

So after reading Kyle Kanos’ comment, I am wondering if the answer is something like this: If $\mathbf{E}$ is the electric field at $z$ due to the whole side of the square loop and we imagine the ...
Joa's user avatar
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-1 votes

Dipoles as vectors

"why does it make sense that the resultant of those dipoles would give the same time period as of the original question" Your point is valid, it does feel and and seems misleading that the ...
Kyathallous's user avatar

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