Electrostatics is concerned with the field and potential of stationary electrical charges and electric charge distributions. Problems are this type are almost exclusively concerned with mathematics of geometries using the inverse-square law.

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Electrostatic charge leakage

What are the ways electrostatic charged objects leak charge in humid conditions? Can airborne particles pick up charge by contact, then be repelled hence removing charge? If so would it be a ...
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1answer
1k views

Minimizing potential energy of a dipole in an electric field

My test paper asked me which way a dipole should be orientated in an electric field to minimize its potential energy. My answer was that the dipole should lie parallel to the electric field with the ...
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1answer
543 views

What is the energy of interaction between a point charge and an infinite cylinder?

I don't remember enough from my electromagnetism course and I can't find any simple, full example on this subject. I know, that I can consider the cylinder as a wire with the same charge density ...
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145 views

electrostatic potential, analytic properties

An electrostatic potential associated with some delocalized charge $\int \rho(\mathbf{r}) d{\mathbf{r}}$ is given by: $$v_H(\mathbf{r}) = \int ...
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2answers
905 views

Electric potential of sphere

(a) I am a little confused about this part. The point at A to B isn't radial. The electric field is radially outward, but if I look at the integral $$\int_{a}^{b}\mathbf{E}\cdot d\mathbf{s} = ...
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4answers
6k views

If something has zero resistance, does it have infinite amperage?

If amps = volts / ohms, and ohms is 0, then what is x volts / 0 ohms?
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69 views

Is it necessary for EM fields to be dependent & co-exist in static conditions?

I was having a discussion today with one my colleagues in the lab about the independence and co-existence of EM fields.$$$$ My argument: In time-varying fields: EM fields are necessary dependent, ...
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1answer
79 views

How to find the electric field of a charged tube?

Let's say there is a charged tube(cylinder with no top or bottom) with radius $a$, length $l$ and charge $q$ and a point which is collinear with the centre of the charged tube. Anyway, since we can ...
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111 views

How to calculate the electrostatic force between two dielectric rings of charge?

Let's say there is a dielectric ring of charge with radius $a$ and charge $q_1$. I could calculate the electrostatic force applied on a point charge with charge $q_2$ and which is collinear with the ...
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3answers
183 views

How can the potential on a cube's surface replicate the potential of a point particle?

If i have a cube (either hollow, or an insulating solid) and i want its surface have a potential such that it looks like a point particle outside of the box does that mean the exact potential on the ...
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1answer
167 views

Charging the plates before making the capacitor

Basically, a simple capacitor will consist of 2 plates and a dielectric material between them, what if i took 2 plates, charged one with a +ve charge and the other with equal -ve charge, then i put ...
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2answers
95 views

Can a liquid insulator be electrically charged by touching a charged conductor?

Can a liquid insulator be electrically charged by touching a charged conductor? I understand that solid insulator will only be charge on the surface where it is touch, but the case is different ...
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1answer
180 views

Potential of a dipole with actual physical extension?

I think everybody here knows the equation that gives the potential of a point like dipole, but how does the field look like if you have e.g. a metal sphere with radius $R$ and a certain dipol moment, ...
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212 views

What happens if we give a single electron charge to a hollow metal sphere?

I found this related question: What happens to 5 electrons on a sphere? But this question describes the case when there can only be 5 electrons on that sphere at all times. The answer linked to the ...
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1answer
149 views

Dielectric modification of electrostatic equations?

I have learnt that in cases of electrostatic fields inside a dielectric of any source charge, the field is reduced by a factor of K( if K, the dielectric "constant", is taken everywhere to be same). ...
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2answers
332 views

Do black holes have charges?

Do black holes have charges? If so, how would they be measured? Also, does electricity behave the same way? Black holes affect photons, which are carriers of EM radiation, so do black holes have any ...
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1answer
226 views

Potential for charge distribution, finiteness

Consider a potential for charge distribution: $$v_H(\mathbf{r}) ~=~ \int \frac{\rho(\mathbf{r'})}{|\mathbf{r}-\mathbf{r'}|}d\mathbf{r'}$$ where $\rho(\mathbf{r'})$ is the charge density. This ...
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2answers
438 views

In which cases is it better to use Gauss' law?

I could, for example calculate the electric field near a charged rod of infinite length using the classic definition of the electric field, and integrating the: $$ \overrightarrow{dE} = \frac{dq}{4 ...
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1answer
316 views

Where is the flaw in deriving Gauss's law in its differential form?

From the divergence theorem for any vector field E, $\displaystyle\oint E\cdot da=\int (\nabla\cdot E) ~d\tau$ and from Gauss's law $\displaystyle\oint E\cdot ...
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26 views

Gauss' law and ions?

My text book says that with we have a singly ionized sodium atom net charge +e and if we choose a spherical surface centered on the ion and large enough to contain it all we do not need to know the ...
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1answer
68 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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3answers
284 views

question on dipole moment of water molecule

I read a line today and don't get it: "Molecules with mirror symmetry like oxygen, nitrogen, carbon dioxide, and carbon tetrachloride have no permanent dipole moments." ...
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0answers
69 views

Measurement of speed of static electric field propagation?

Could one measure the time delay between charging up an electrode and measuring the static electric field at some distance? For example I've looked up the specifications of an Electric Field Meter ...
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1answer
81 views

Distribution of charge over a conductor?

Excess charge in a conductor is supposed to distribute itself evenly over the surface of the conductor. If the conductor has a charge of $2e$ how would the charge distribute itself? There's no way you ...
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127 views

Field inside a conductor?

If the above image is a cross section of a conductor, the field at the point shown is not zero. So the field inside a conductor is not zero at all points. You could argue that the electrons would ...
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1answer
503 views

how can electromagnetic waves reach a cell phone in faraday cage?

is there any way to make electromagnetic waves reach a cell phone in faraday cage although conductor surround cell phone everywhere , can we pass current through conductor to make charges move as a ...
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2k views

Electric field due to nonconducting sphere

For calculating electric field outside a nonconducting sphere with a hollow spherical cavity. When I use the rule (Charge density= $dQ/dV$), I don't know exactly what is $dV$, is the volume here ...
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157 views

Is it possible to charge a capacitor to any potential? Does it depend on the dielectric placed between them?

Is it possible to charge a capacitor to any potential? Does it depend on the dielectric placed between them? Or, are there other factors affecting it?
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Gauss's (Divergence) theorem in Classical Electrodynamics

How does divergence theorem holds good for electric field. How does this hold true- $$\iiint\limits_{\mathcal{V}} (\vec{\nabla}\cdot\vec{E})\ \mbox{d}V=\mathop{{\int\!\!\!\!\!\int}\mkern-21mu ...
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4answers
2k views

Resistance between two points on a conducting surface

Suppose we have a cylindrical resistor, with resistance given by $R=\rho\cdot l/(\pi r^2)$ Let $d$ be the distance between two points in the interior of the resistor and let $r\gg d\gg l$. Ie. it is ...