A law in Classical Electromagnetism and Newtonian Gravity.

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How does one come up with the Coulomb's law?

My teacher mentioned that field line density = no. of lines / area and the total area of a sphere is $4\pi r^2$ and so an electric force is inversely proportional to $r^2$. Actually, why can the total ...
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789 views

Could someone remind me of what we mean by zero electric field “inside” a conductor?

If I have a spherical conductor (perhaps a shell) and "inside", as in the hollow area there is nothing. The electric field is 0. But what happens if there is a charge "inside" (not like inside the ...
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328 views

Gravimagnetic monopole and General relativity

Review and hystorical background: Gravitomagnetism (GM), refers to a set of formal analogies between Maxwell's field equations and an approximation, valid under certain conditions, to the Einstein ...
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2answers
6k views

Using Gauss's Law to calculate electric fields between plates

I have two earthed metal plates, separated by a distance $d$ with a plane of charge density $\sigma$ placed a distance $a$ from the lower plate. I want to derive expressions for the strength of the ...
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44 views

Electric Flux - What is the point?

Electric flux is a defined quantity that is proportional to the no. of field lines passing through a given area element for a given electric field. It is not proportional to the relative density of ...
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48 views

Calculating flux of axisymmetric electric field through a sphere [closed]

The following problem and its solution is taken from I. E. Irodov's book basic laws of electromagnetism : I do not understand how the fact that field is axisymmetric leads to the conclusion that ...
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57 views

What is the charge density in the proof of Earnshaw's theorem?

I am trying to understand the proof for Earnshaw's theorem. Though the theorem states that a collection of point charges cannot be maintained in a stable stationary equilibrium configuration ...
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69 views

Gauss's law not making sense

If we have a point charge and outside of it we have a non-conducting Gaussian sphere, then Gauss's law says that the net flux should be zero. I agree that the total field lines coming in are equal to ...
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1answer
18 views

How does the dieletric displacement change among two dieletric materials?

Here's a question I am working on. "A sphere of linear dielectric material with permittivity $\epsilon_1$ and radius $a$ is surrounded by an infinite region of linear permittivity $\epsilon_2$. In the ...
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2answers
63 views

Relation between electric field and dipole moment

I want to show the following equality $$\int_{\left|\vec{r}\right|<R}d^3r\vec{E}\left(\vec{r}\right)=-\frac{\vec{p}}{3\epsilon_0}$$ where $\vec{p}$ is the dipole moment of a charge distribution ...
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80 views

Can Gauss' and Ampere's Laws be written in terms of the divergence of an energy four-vector?

In the first 20 minutes of this video, Susskind derives the continuity equation for charge conservation: $$\dot{\rho}+\nabla\cdot\vec{J}=0$$ (Where $\vec{J}=\frac{\partial\dot{q}^m}{\partial A^m} ...
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635 views

Gauss Theorem:Electric field of an uniformly charged non-conducting spherical shell

I want to know the electric field of an uniformly charged non-conducting spherical shell. I know that in case of conductors(metals),the sphere can be shell or it can be solid,but in both the cases ...
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180 views

Gauss's Law :Electric field due to uniformly charged sphere

While determining the electric field due to a uniformly charged conducting or non-conducting sphere,does the sphere is considered hollow or it is considered solid? Can anyone really state , what is ...
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1answer
178 views

Gauss's Law :To find the Electric Field for a Non-Conducting Sphere

While determining the electric field in a Non-Conducting Sphere using Gauss's law,why the positive charges are considered inside the surface,but in determining the electric field in a conducting ...
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2answers
225 views

What is the difference between electric charge and electric flux?

What is the difference between electric charge and electric flux? According to my knowledge electric flux is nothing but electric charge enclosed by the closed surface.
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Potential difference between point on surface and point on axis of uniformly charged cylinder

Question: Charge is uniformly distributed with charge density $ρ$ inside a very long cylinder of radius $R$. Find the potential difference between the surface and the axis of the cylinder. Express ...
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1answer
363 views

Electric Field at surface/side of cylinder [closed]

I know I can use Gauss's law to find the Electric Field inside and outside the cylinder very easily. We can select Gaussian surfaces for different cases (i.e. $r \lt R$ and $r \gt R$, where $R$ is the ...
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1answer
78 views

Gaussian surface and and Gauss law

Can we consider a cube as a Gaussian surface, for a point charge located at its center.since,Gaussian surface is a closed surface which has a constant electric field but in this case the both the ...
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1answer
129 views

Am I interpreting Gauss' Divergence Theorem correctly

I was reading Introduction to Electrodynamics by Griffiths and I wanted to check if I understood Gauss' Divergence Theorem correctly. The theorem states: $$\int \int \int_V \vec{\nabla} \cdot \vec{C} ...
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2answers
630 views

Electric flux due to external charge

Why is electric flux due to external charge i.e a charge outside a closed surface equal to 0? P.S:Moreover I found this statement confusing:- Electric field appearing in the Gauss' law is the ...
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1answer
910 views

Electric field outside a sphere with a cavity

I have a sphere of radius $2a$ centered at the origin and made of a nonconducting material that has a uniform volume charge density $\rho$. A spherical cavity of radius $a$ eccentric to the right side ...
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1answer
355 views

Applying Gauss' Law to find Electric Field

I'm in doubt in the application of Gauss' Law to find electric fields when the charge distribution is symmetric. Well, first of all: I know how to find the magnitude of the field - we just enclose the ...
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1answer
211 views

Gauss's Law in action

Need someone to tell me if I got this done correctly (a) Draw Gaussuian cylinder inside the black cylinder to find charge enclosed $Q_{en} = Q(\frac{r}{a})^2$ Apply Gauss's Law $E2\pi r \ell = ...
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19 views

Electric Flux - Vector Components

How is $vcos(\theta)$ the perpendicular vector? I think I'm missing something fundamental in my trig and vector knowledge...
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1answer
49 views

Wait… why exactly does farady's ice pail experiment prove Gauss's law?

You'll notice there are no equations in this: that's because this is a question of morale, not of math. But a humble one at that! I come to learn, not to expound. But don't let that limit the form ...
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1answer
29 views

Divergence of a vector field, going through the math [closed]

The example I'm working on has this given identity: $\bigtriangledown \cdot \mathbf{\bar{r}}=3$. The question is: find the divergence of a vector field $\bar{\mathbf{E}}=\frac{\mathbf{r}}{r^{3}}$. ...
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1answer
52 views

Why does $E = 0$ inside conducting sphere? [duplicate]

Given this picture, I've understood that giver r>R, E = q/(4πεR^2) but I just can't get why inside the sphere, E equals 0? And the notes don't explain something. I've tried to look it up on the web ...
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1answer
51 views

Electric flux of a closed surface, $\Psi = Q $ or $\Phi =\int\vec{E}\cdot d\vec{A}$

I have problem with the equation of electric flux. I use one book of fundamental physics and another book of electromagnetic engineering; the two of them give different equations for electric flux. ...
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1answer
64 views

How can electric field representation be obtained from Enge representation using Maxwell's equations?

Suppose we have a long electric capacitor. Let $L$ be its length ($z$ coordinate), $W$ its width ($y$ coordinate), and $D$ its full height (full aperture; $x$ coordinate). Let $L\gg W\gg D$. The ...
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65 views

Does Gauss' Law apply to real physical solid conductors?

In a conductor there is no electric field because there is no charge. There is no charge inside because any charges present inside would repel each other and be driven to the surface of the conductor. ...
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0answers
28 views

Does gravity weaken by the square of the distance because the energy is dispersed over the square of the distance [duplicate]

The area of a circle is $\pi r^2$ if you increase $r$ the area will increase by the square so if this area was of energy and you increase the area it is dispersed you would expect its energy to weaken ...
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2answers
93 views

Two capacitor plates with equal positive charges $q$

I read in a book that if both the plates of a parallel plate capacitor are given equal positive charges $q$, then the charges on the facing surfaces will be zero and the charge on the outer surfaces ...
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0answers
27 views

Guides for solving E&M problems [duplicate]

I am an undergraduate physics student in a university and I am looking for a good guide or a handbook with lots of questions and full answers in subjects such as Gauss' law and Maxwell equations to ...
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1answer
89 views

Flux on a Gaussian surface between two charged plates

If we have two parallel charged plates, equal and opposite in charge: What is the flux felt on a Gaussian surface between them? surely it sum to 0 as each amount of flux will enter and then leave? ...
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57 views

Law of Gauss. Electrostatics

I have seen on the internet that many times people assert that inside a cylindric condenser the electrostatic field is null due to the fact that the Gauss flux inside is null. But I wanted to make ...
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0answers
30 views

Electric field for two adjacent infinite layers of width h charged + and − uniformly

I'm trying to figure how to calculate the electric field created by two adjacent infinite layers of width h charged + and − uniformly. I don't understand why isn't the field outside of the layers ...
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1answer
307 views

Apply Gauss' Law to find Electric Field around nonconducting plastic sheets

The question: Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities $\sigma_1$,$\sigma_2$,$\sigma_3$ and $\sigma_4$ on their surfaces, as shown in the ...
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0answers
34 views

Proof of Gauss' Law [duplicate]

How would you prove Gauss' law for an asymmetrical closed surface? I can find it for symmetrical surface but couldn't for Asymmetrical surfaces.
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1answer
110 views

Gaussian Unit of Charge and Force

I just read that in the Gaussian Units of charge The Final equation in Coulomb's law is as simple as $$\boldsymbol{F}=\frac{q_1q_2}{r^2}$$ No $\epsilon_0$ no $4\pi$ like you have in the $\mbox{SI}$ ...
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1answer
105 views

Flux if there were only one type of charge in the universe

There was this question that i saw in a book and it also had an answer given. The Question was: If there were only one type of charge in the universe, then: $\phi = \oint ...
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1answer
153 views

Physical interpretation of $\iiint (∇\cdot\vec E)\mbox{d} V$ [duplicate]

Can anybody explain the physical interpretation of Gauss's law $$\iiint (\nabla\cdot \vec E)~\mbox{d}V~=~\frac{Q}{\epsilon_0}? $$ Also, how is the differential form of Gauss's law obtained from ...
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0answers
28 views

Gauss's Theorem in electricity and its gravitational counter part [duplicate]

We all know the Coulomb's law is the electrostatic counter part of the Newton's law of gravity.So by considering a gravitational potential,is there a gravitational counter part for Gauss's theorem in ...
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1answer
278 views

Why is electric flux through any closed surface $q/\epsilon_0$?

Why is electric flux through any closed surface $q/\epsilon_0$? In schools we are only taught of its simplest case, i.e. flux through a sphere with charge centered at origin. And then it is ...
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1answer
4k views

Net flux calculation through a cube [closed]

Ans: Applying Gauss’s law the net flux can be calculated. And for option (B), I guess the flux will be 0. But not sure. Can anyone explain all the 3 options? For left and rignt face, EA = ...
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1answer
8k views

Electric field due to nonconducting plastic sheets [closed]

Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities $\sigma_1, \sigma_2, \sigma_3$ and $\sigma_4$ on their surfaces (the four surfaces are in the ...