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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Conductors and Uniqueness Theorem

I'm working with Griffiths Electrodynamics, and he introduces a uniqueness theorem: First Uniqueness Theorem: The potential $V$ in a volume $\Omega$ is uniquely determined if (a) the charge density ...
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2answers
38 views

How does electrostatic force affect electronic devices?

How does electrostatic force generated by two seperate plates having opposite charges affect electronic devices? I know that magnetic fields have some harmful effects to electronic devices but I am ...
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1answer
11 views

Using Maximum Principle to see conductor is equipotential

This is a problem from electrostatics, but I'm trying to understand it in terms of harmonic functions. Let $B\subset\mathbb{R^3}$ be a conductor. It can be shown that the electric potential ...
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1answer
39 views

Curvature of electrostatic potential is zero

Could you please expound upon this claim? I found such claim on Zangwill's Classical Electrodynamics, which states that constraint coming from Laplacian equation implies electrostatic potential has ...
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3answers
79 views

What is special about the ratio $Q/V$ that we give it the name Capacitance?

Why is the ratio Charge/Potential important? Also, usually when we add charge, the potential changes. Then why do we care how much charge we can put on a conductor for a given potential.
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2answers
766 views

Why is the shape of lightning or an electric spark a zig-zag line?

Why is the shape of the lightning (or an electric spark) always of a zig-zag nature? Why is it never just a straight line? Image source.
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1answer
460 views

Electric field from conductive to dielectric media

I am interested in the main difference between transitions from electric fields from Conductive to Conductive/ Dielectric to Dielectric and Dielectric/Conductive media. What are the boundary ...
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1answer
69 views

Does charge of a metal charged by induction determine by which ends of the metal is grounded to?

Does charge of a metal charged by induction determine by which part of the metal is ground to? I draw a diagram to make it simple to understand: Right diagram: When ground is touched with the ...
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1answer
189 views

Finding Green function using eigenfunction expansion method

Given the Dirichlet boundary condition, I am to show that the functions that satisfy $(\nabla ^2 + k_{lmn}^2) \psi_{lmn} (x,y,z) = 0$ are given by $\psi_{lmn} = (\frac{\pi}{2x})^{1/2} J_{l+1/2}(x) ...
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3answers
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Can two electrons get ever so close as to touch each other?

My friend and I were studying for our EM test when we started to think about what happens to the electric field near an infinite line of charge. $$E = \frac{\lambda}{2\pi\rho\epsilon_{0}}$$ As you ...
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3answers
14 views

Why static electricity only concentrates and flows on the surface?

Anything insides Faraday Cage or Faraday Suit is protected from Electric Field outside. I don't understand what restricts the flow of free electrons to surface on the cage only? How does that happen? ...
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2answers
491 views

How do I express the interaction energy between two charged spheres?

Consider two identical insulating spheres each with radius $R$ and uniform charge $Q$ through their volume. They are separated from their centers by a distance of $d>2R$. Here is my general ...
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2answers
107 views

What is the minimum distance between two opposite point charges

In an overly simplistic model if I have a single negative charge, and a single positive charge they will be attracted. I expect they will fly together. Click. Good luck getting them apart. The ...
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1answer
333 views

Dielectric slab counter-intuitive formula?

For the calculation of force on one of the two equal(in magnitude, opposite in sign) point charges separated by $r$ with a dielectric slab of dielectric constant $K$ and width $d$ in between, the ...
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1answer
144 views

Earnshaw's theorem and springs

Earnshaw's theorem states that the Laplacian of the potential energy of a small charge moving through a landscape full of static negative and/or positive charges (and gravity) is zero. Thus you can't ...
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1answer
47 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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0answers
35 views

Find the field of two infinite strips of width $b$ [on hold]

Q:The two charged strips in the following picture have width $b$, infinite height,and negligible thickness(in the direction perpendicular to the page).Their densities per unit area are $\sigma$ ...
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2answers
266 views

Effect of charges near a parallel plate capacitor

If I charged a parallel plate capacitor. And then, I insert a charged body near one of the plates. Will there be any interactions like attraction or repulsion? What if I disconnected the battery?
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1answer
45 views

Can you get a static shock in a vacuum if you are not touch the object?

For example when you hop on a trampoline sometimes you will be shocked before you even touch the tramp. Does the shock have to pass through the air to get to you or can it work in a vacuum?
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1answer
26 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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0answers
14 views

What will be the electric field intensity? [on hold]

Ì have a problem here I tried to solve it but I am not able, so it goes like this. If the surface area is 10 cm2 and the electric flux is 25 NM2 C-1, find the electric field intensity?
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3answers
464 views

Where's the energy in a boosted capacitor?

Suppose I look at a parallel plate capacitor in its rest frame and calculate the electrostatic energy, $E$. Next, I look at the same capacitor in a primed frame boosted in the direction perpendicular ...
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0answers
9 views

What are the limiting conditions for one side of a charged parallel plate capacitor to discharge to ground [duplicate]

@annav Earlier I asked a similar question with full description but the stackexchange system put it on hold. It is entitled "to annamitra palit re capacitor discharge" . I am stumped by the fact ...
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42 views

To Annamitra Palit re capacitor discharge [on hold]

@Anamitra Palit , I have read the discussion of 2012 re discharge of a parallel plates cap to ground from one pole, and was quite confused. So I made a series of experiments charging a 1 microFar cap ...
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24 views

Is there any simulation program for electrostatic and magnetostatic fields? [duplicate]

please can any one suggest me a good program for simulating electrostatic and magnetostatic fields (forces,flux density, energy and potential) ?
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2answers
29 views

Confusion about Gauss's law for Electrostatics

I just learning about Gauss's law in integral and differential form. There's something I'm a bit confused about: Let $\vec{r}$ be the location of your test charge with respect to the origin, and ...
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1answer
28 views

Potential Differences (Voltage) from Point Charges [on hold]

Identical +1.8 micro Colomb charges are fixed to adjacent corners of a square. What charge (magnitude and algebraic sign) should be fixed to one of the empty corners, so that the total electric ...
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3answers
678 views

How can I find the potential created by spherical capacitor with dielectric material?

If we have a spherical capacitor with inner radius or r1 and outer radius of r2, with charges (+/-)q on them and there is a dielectric material (with constant e) in between them with. What kind of a ...
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15 views

Conductor related stuff [closed]

I am having trouble dealing with conductors, especially the part where fields outside and inside are asked. The problem 7 deals with conductors. A detailed answer would help me.(Problem 6 not related ...
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2answers
39 views

Draw the charge configuration according to the electric field [closed]

I'm trying to draw the charge configuration outside the regions that lead to the given electric field patterns. Can someone show me how?
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1answer
112 views

Boundary conditions in Electrostatics

If I have a grounded conducting material, then I know that $\phi=0$ inside this material, no matter what the electric configuration in the surrounding will be. Now I have a conducting material that ...
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2answers
39 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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0answers
18 views

Will charges redistribute on the surface of an insulator?

When I shot an electron beam onto an insulator, electrons will be knocked out of the material, leaving an immobile positive charge at their place. Some of the knocked out electrons might manage to ...
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2answers
45 views

Relationship between surface density and volume density

Often in an E&M problem, I'm having to "chop" an extended object into an infinite sum of smaller extended objects which I know more about to find a potential or electric field or whatever. The ...
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33 views

Laplace's equation with spherical, cylindrical, and planar symmetry [closed]

Find the general solution to Laplace's equation for spherical symmetry (everything can only depend on $r$, the radius), cylindrical symmetry (everything can only depend on $s$, the radius), and ...
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1answer
191 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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1answer
53 views

Electron electric field

As we know the fundamental unit of charge in our universe at the time of electrodynamics was an electron, and in any frame of reference, its radius is a finite number and assuming uniform charge ...
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28 views

How does a battery work?

How does the positive terminal of the battery attract electrons? Does the electric field emitted by the positive terminal attract the electrons?
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1answer
57 views

Help understanding the solution to a problem regarding kinetic energy of a group of point charges

The problem provided by my professor goes as follows: "Now consider a situation in which all charges are equal to q and they simultaneously become "unglued". What speed will each charge have when a ...
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1answer
51 views

Two spherical cavities hollowed out from the interior of a conducting sphere. At the center of each cavity a point charge is placed

From Griffiths: Two spherical cavities, of radii a and b, are hollowed out from the interior of a (neutral) conducting sphere of radius R. At the center of each cavity a point charge is placed – ...
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0answers
17 views

Finding the contained charge in a box, given the $E$-field [closed]

I'm not sure whether my approach is correct for this problem, it's been a while since I've touched E&M. I thought it best to check, as I'm not sure whether $0$ is the proper answer. I've got a ...
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0answers
8 views

How does one determine the breakdown voltage of a solid-in-liquid suspension?

So I'm doing a project in which we are supposed to collect micro-scale conducting metal particles from a suspension of it in water (which is deionized). Suppose that I am charging the particles ...
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1answer
32 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
14 views

Electrohydrodynamics: How will electric potential develop in a fluid when potential is applied from ends

Lets say, I have a fluid in a rectangular enclosure (2D). I apply electric potential $U=U_1$ at left boundary and $U_2$ at right boundary. In the lower and upper boundaries, the potential varies ...
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2answers
73 views

Charge outside Gaussian Surface doesn't contribute to Flux?

I roughly understand the explanation for this: any electric field line that enters the surface, must leave it, since field lines can't terminate abruptly in space. My question is, what if you have a ...
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2answers
37 views

Net Electrostatic Field inside a Conductor is $\vec{0}$

I've heard an explanation for this, and my professor wasn't really able to clarify my questions, so I was hoping someone could help: Suppose there is an electrostatic field $\vec{E_{net}}\ne\vec{0}$, ...
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0answers
7 views

Would the charges on a superconductor near an another charged conductor move and produce magnetic field?

When there is a charged conducting object near an another charged conducting object the charges on these objects accumulate to the sides where the closest points between these objects are. However, ...
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4answers
4k views

Electric field outside a capacitor

I know that the electric field outside of a capacitor is 0 and I know it is easy to calculate using Gauss's law. We create cylindrical envelope that holds the same amount of charges (of opposite ...
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1answer
56 views

Earnshaw Theorem for ionic solids

Is a single molecule of sodium chloride (say) or a cluster of molecules of NaCl unstable, although macroscopically NaCl is in fact, stable? How can I reason this based on Earnshaw's theorem?
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1answer
33 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 ...