1
vote
2answers
33 views

Does the induced charge on a conductor stay at the surface?

My textbook says that when a conductor is placed in an electric field, the electrons in it realign so that the net electric field inside the conductor is zero. There isn't a proof for this. It merely ...
1
vote
0answers
33 views

Charge distribution inside a parallel plate capacitor [on hold]

I'm having difficulty deriving a known expression for the magnitude of the Electric Field within a parallel plate capacitor with applied potential difference $V$ and an immobile charge distribution ...
8
votes
3answers
413 views

Electric Field inside a regular polygon with corner charges

If we have equal charges located at the corners of a regular polygon, then the electric field at its center is zero. Are there other points inside a polygon where the field vanishes? The simplest ...
0
votes
0answers
22 views

Calculation of the electric field from a cube of charge with charge density proportional to radial distance [closed]

I have a cube of side length $L$ centered at the origin and total charge $Q$; the charge density is $\rho(r)\propto r^n$ for some integer $n$, where $r$ is the radial distance in spherical ...
3
votes
0answers
54 views

Electric field in a sphere with a cylindrical hole drilled through it

Suppose that you have a sphere of radius $R$ and uniform charge density $\rho$; a cylindrical hole with radius $a$ ($a\ll R$) is drilled through the center of the sphere, leaving it like a "necklace ...
3
votes
1answer
54 views

Does it really make sense to talk about field lines?

Field lines should only provide a visual representation of a field. There is a rule for their construction: take an object subject to a field, move it by d$\mathbf{r}$ and draw the direction of the ...
6
votes
5answers
1k views

Why can two (or more) electric field lines never cross?

The the title is self explanatory, I guess. Why can two (or more) electric field lines never cross?
7
votes
6answers
600 views

Why cant Electrostatic field lines form closed loops?

My physics textbook says "Electrostatic field lines do not form closed loops. This is a consequence of the conservative nature of electric field." But I cant quite understand. Can anyone elaborate? ...
1
vote
1answer
59 views

Field from non-conducting plate?

For a non-conducting sheet, the electric field is given by: $$E = \frac{\sigma}{2\epsilon_0}$$ where $\sigma$ is the surface charge density. This equation holds well for a finite ...
1
vote
1answer
56 views

Electric field near surface of a conductor? [duplicate]

If the electric field on a positive charge is non-zero, then the charge accelerates in the direction of the field. The field at the surface of a conductor is perpendicular to the surface. Why ...
0
votes
1answer
105 views

Calculating the electric potential in cylindrical coordinates from constant E-field

I am having so much trouble with this problem. I feel like I shouldn't be, but I am. A uniform electric field, $\vec{E} = E_0\hat{x}$. What is the potential, expressed using cylindrical ...
2
votes
3answers
80 views

Calculating the Potential from the E-Field

I find that often times I'll be tripped up by questioning whether or not I can do something mathematically, and be unable to come up with a satisfying answer. This is, unfortunately, one of those ...
6
votes
2answers
119 views

Quantization of electrostatic $\vec E$ field?

Can a electrostatic field $\vec E=\vec E(x,y,z)$ (time-independent) or electrostatic potential $\phi=\phi(x,y,z)$ be quantized? If yes, will these quanta be photons again? But we don't have an ...
-1
votes
1answer
48 views

Electric Potential Energy

When work is done on a positive test charge by an external force to move it from one location to another, does the potential energy increases or decreases, and does the electric potential increases or ...
3
votes
1answer
75 views

Are the axial electric field lines of a dipole the only ones that extend to infinity?

Consider an electric dipole and its electric field lines. There will be many field lines that do not extend to or originate from infinity, but rather begin at the positive charge and loop back ...
0
votes
0answers
30 views

Force exerted by a capacitor on a polar object

I was reading about capacitors and wondered what the force an electrostatic field created by a capacitor would be on an object with a certain charge and mass. If it can exert a force on a polar object ...
2
votes
1answer
232 views

Finding electric field between overlapping surfaces [closed]

The problem is: A sphere with radius R is centered at the origin, an infinite cylinder with radius R has its axis along the z axis, and an infinite slab with thickness 2R lies between the planes ...
1
vote
0answers
72 views

Electric potential on a uniformly charged tube

A hollow cylinder, with no top or bottom, of radius $R$ and length $L$ is uniformly charged with density $\sigma>0$. I have to find the point on space where a point charge $q>0$ has to be drawn ...
0
votes
0answers
81 views
0
votes
0answers
124 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 ...
0
votes
1answer
49 views

Electric field from a sheet of charge?

Does anyone have images of the electric field created by a real plate of charge? I'm not looking for an image of a theoretical infinite sheet of charge, I'm looking for an image of a real large one. ...
1
vote
1answer
290 views

How to choose Gaussian surfaces while solving problems?

I have a doubt regarding this problem: Two large identical flat metal plates are placed parallel to one another, seperated by a small distance compared to their linear size. One plate is given a ...
0
votes
1answer
78 views

Show that the electric field, $\mathbf{\vec{E}}$ cannot be generated by any static distribution of charges

Show that the electric field $$\mathbf{\vec{E}}=\begin{pmatrix}0 \\ E_0x \\ 0\end{pmatrix}$$ where $E_0$ is a constant, cannot be generated by any static distribution of charges. I understand ...
-1
votes
1answer
67 views

What is opposite of electric field?

A negatively charged molecule will generate a field, an electric field, and it will repel all negative ions. So what does positively charged molecule generates that causes other positive molecules ...
1
vote
1answer
93 views

Can the electric field — always — be derived from the potential?

After studying the definition (& derivation) of the potential to an electric field and the Poisson equation I'm currently wondering whether the following is possible: Can one give an example of ...
3
votes
2answers
121 views

Relation between Gauss' law and Coulomb's law

In Coulomb's law if the relation was as if electric field intensity was to vary inversely $1/r$ with distance rather than the inverse $1/r^2$ of square of distance, would the Gauss's law still be ...
7
votes
1answer
84 views

Does an electric field create a pH gradient?

Since pH is a measure of the effective concentration of $\mathrm{H}^+$ ions a solution, I expect that an electric field applied to a solution will create a pH gradient. The higher concentration of ...
2
votes
2answers
194 views

Motion of a dipole in an electric field

Assume that we have some non-constant electric field $E(x,t)$ and a point-dipole at a position $q$ with a constant dipole moment $\vec{p}$. How would you describe the time evolution, i.e. the motion ...
2
votes
1answer
82 views

Static electricty and fields inside of the conductor?

I have a few related questions about static electricity and conductors. 1. when we say static electric field inside a conductor is zero, let us take an example of two concentric conductors, outer one ...
1
vote
2answers
2k views

If we change the radius of spherical surface does electric field or flux change?

Suppose a point charge is located at the center of a spherical surface. The electric field at the surface of the sphere and the total flux through the sphere are determined. 1).What happens ...
7
votes
7answers
542 views

Electric field lines density

When we're dealing with problems in electrostatics (especially when we use Gauss' law) we often refer to electric field lines density which is inversely proportional to radius in case of a single ...
2
votes
0answers
224 views

Calculating Electric Field from a Potential Difference w/o Charge

So here is my homework question: Two long cylindrical shells of metal (radii $r_1$ and $r_2$, $r_2 > r_1$) are arranged coaxially. The plates are maintained at the potential difference ...
0
votes
0answers
97 views

Variation of electric field and current flowing

Theoretically, a change in either electric or magnetic field will cause a current to flow , I am already familiar to Faraday's law of electromagnetic induction, so I tried to search about producing a ...
9
votes
3answers
447 views

How would charge be distributed in charged conductors if the Coulomb law was not ${1}/{r^2}$?

Would the excess charge on a conductor move to surface until the electric field inside become zero if the Coulomb law was for example $\frac{1}{r^3}$? If yes, would the distribution $\sigma(x,y)$ be ...
2
votes
2answers
3k views

Electric Field Between Two Parallel Infinite Plates of Positive Charge and a Gaussian Cylinder

Is the electric field between two positively charged parallel infinite plates one with a charge density twice the other effect the electric field on the outside of the plates? I am thinking no, ...
1
vote
1answer
57 views

Need a more efficient way to find where the $E$ field is zero

So this is a problem I already know how to solve, but I feel like my method is really inefficient and I'm wondering if there's a more intuitive, less tedious way to arrive at this conclusion. If we ...
-2
votes
2answers
364 views

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 ...
0
votes
1answer
85 views

Cylindrical charge distribution [closed]

I'll just list the problem first and then explain what I need help with. Consider a cylindrical charge distribution extending from $r = 0$ to $r = 8.2 $cm of charge density $\rho = r/a_0$, where ...
1
vote
1answer
233 views

Does the electric field change only inside the dielectric, or even after exiting the dielectric?

I know that the field inside a dielectric is changed and is $\epsilon$ times less the original field (some books use $K$ for this constant). This is because the induced field inside the dielectric is ...
1
vote
2answers
552 views

Electric field. Linear charge density [closed]

I was wondering if anyone could help me out in this exercise I've been struggling to solve. A straight, nonconducting plastic wire $ 8.50 cm $ long carries a charge density of 175 $ nC/m$ ...
3
votes
2answers
1k views

Using the image charges method to find the electric field

The following is a question from a tutorial in my Physics 2 course about conductors and the Method of image charges. We are given two infinite perpendicular and grounded plains. The first ...
2
votes
2answers
1k views

Why does the electric field perpendicular to every point on the surface of a conductor?

I am reading Berkeley Physics Course, Volume 2 (Electricity and Magnetism by Edward M. Purcell). I am in chapter $3$ pg $92$, and the book discusses conductors. The following is from the book: ...
2
votes
2answers
2k views

Calculating the field of an infinite flat sheet of charge using the superposition principle

I am trying to calculate the field of an infinite flat sheet of charge (a plain with uniform charge density $\sigma$) using the superposition principle. I know that the field of an infinite line ...
3
votes
2answers
379 views

Potential of arbitrary charge distribution

Imagine this: You have a sphere of air where you have no charge and around this sphere you have a charge distribution $\rho(r,\theta,\phi)$. (For instance, this could be ...
1
vote
1answer
141 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, ...
0
votes
1answer
87 views

Electric dipole, error in calculation

Currently I am calculating the dipole moment of a metal sphere in a uniform electric field $E_0$ in z-direction. From here I know that the charge density look at page 15 is given by $ 3 \epsilon_0 ...
0
votes
0answers
193 views

Electric field of uniformly charged spherical cap?

I was wondering what the electric field of a uniformly charged spherical cap is? Thereby I am referring to a spherical shell that was sliced into two pieces and we are only looking at one part of it. ...
0
votes
1answer
125 views

One terminal of an ideal voltage source connected to earth->Massive current will flow?

Assume we have a "somewhat" ideal voltage source like a DC power supply powered by mains. Take just one terminal and form a conductive path between it and earth ground. Assuming that no conductive ...
1
vote
2answers
308 views

Why is electric flux defined as $\Phi = E \cdot S$?

Flux, as I understand it, is the amount of substance passing through a particular surface over some time. So, from a simple perspective, considering photons that go through some virtual surface $A$ ...
0
votes
2answers
147 views

Field lines question

A friend of mine asked me this question, that is asked in an entrance examination. It shouldn't be that difficult, but I fail to find a rigorous answer for it. The figure shows three charges, that ...