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Questions tagged [electrostatics]

Electrostatics is concerned with the electrical fields and scalar potentials of stationary electrical charges and charge distributions. Use this for questions about electromagnetic situations in which currents and magnetic fields are absent, otherwise use [tag:electromagnetism] and/or [tag:magnetic-fields]

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Why there is a negative sign in the formula of calculating work done in electrostatics?

$$W = - \int _ { a } ^ { b } \vec { F } \cdot d \vec { r }$$ ( from The Feynman lectures on physics vol. 2, new millennium edition, page 4-4) In this formula why there is a negative sign in the ...
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0answers
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Electrical induction through capacitors

How electrical induction takes place in flow of current in a transient capacitive DC circuit?
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1answer
20 views

Self-energy of conducting shell

While calculating self energy of a conducting shell we integrate $Vdq$,where $V=\frac{q}{4π\epsilon r}$, but when the $dq$ charge is bought close to the shell it changes the charge distribution on the ...
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3answers
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Is a complete circuit required for capacitors to redistribute charges?

Suppose I have two capacitors of different capacitance $C_1$, $C_2$and they have been charged prior connecting by voltage of $V_1$ and $V_2$ respectively the positive plate of one capacitor is ...
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1answer
17 views

Electric Field calculation [on hold]

What are the limits(lower and upper) of electric field of the differential element in the calculation of electric field of some standard configuration Eg: electric field calculation for spherical ...
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0answers
26 views

Terminal Voltage of Duoplasmatron and ion beam energy

I'm planning on buying a Duoplasmatron, the sales representatives asks me for what is the requirements for the Terminal Voltage and ion beam energy. What I should I answer, since the terminal voltage ...
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1answer
27 views

one terminal of battery connected to opposite terminal of identical battery

I have read almost all answers on PSE and ESE but none of them are to the point or maybe I am not understanding.I have described the setup in the title , I just want to know what will happen , will ...
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1answer
22 views

charge given to parallel conducting plates [duplicate]

Whenever a charge say $Q_1$ and $Q_2$ is given to identical conductors we have to assume that charge is given to their outer side and not inner side to calculate redistribution. Why? I tried to find ...
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0answers
19 views

Electric field due to conducting shell

charges q1 and q2 lie inside and outside of an uncharged conduncting shell.What's the elcetric field on q2 (which lie outside).Their sepration is r Will there change in electric field if there was no ...
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1answer
23 views

Sign issue deriving SHM of Electric dipole in external uniform electric field

If we have an electric dipole as shown: Net torque on system = $Fdsin\theta$= Rate of change of angular momentum = $I \ddot \theta $ For small displacements along line of E field, $sin\theta \...
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0answers
34 views

Why is the electric field inside this cavity (inside a metal conductor) 0?

Assume a spherical cavity inside a spherical metal conductor. If I draw a gaussian surface (a sphere) which encloses the cavity, the charge enclosed must be 0. Thus the charge inside is 0 or there is ...
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0answers
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electrostatics hollow cylinder electric field [on hold]

charges are so arranged on the surface of an infinitely long hollow cylinder that the right hand half of the cylinder surface from the section OO' is charged positively and the left hand half ...
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2answers
34 views

Is it true that any electrostatic charge density can be represented by Dirac Delta function? Give me a general example

My college professor said that any charge density can be replaced by Dirac Delta function but how I want to know.
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1answer
42 views

Why should there be electrostatic equilibrium inside a conductor? [duplicate]

I have been trying to understand why the net electric field inside a conductor is zero regardless of the exterbal electric field. But why should equilibrium ever be attained?
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2answers
41 views

Does current flow in the wire when only one terminal of the battery is earthed?

Let me specify beforehand that this question has been asked previously but I haven't been able to satisfy my curiosity.I know a battery maintains a potential difference between it's terminals , let's ...
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2answers
33 views

What is the relation between the frequency of the light produced and the acceleration of the charged particle

We know that accelerating charges produce EM radiation. Can we derive a relation between frequency of the light produced and the accelaration of the charge ?
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0answers
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Charge placed inside two shells [on hold]

Suppose there are two neutral conducting concentric shells. A point charge is placed at the center of shells. The shells are neutral. We have to find the electrostatic potential energy of the system, ...
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0answers
27 views

Unable to reach the required solution in a problem of Electrostatics [on hold]

Two identical pith balls, each of mass $m$ and carrying identical charges $q$ each, are suspended from a common point by two strings of equal length $l$. The angle between the string is $2\theta$, and ...
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0answers
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Why a neutral metal sphere inside uniform electric field is equipotential

I know that due to ext electric field the sphere will be polarised and net electric field inside it would be 0. However on its surface at 2 opposite ends 2 charges of equal and opposite magnitude ...
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0answers
16 views

Is the potential difference equal for n identical capacitors connected in series? [on hold]

(https://i.stack.imgur.com/Pfit8.jpg) Is the potential difference equal for n identical capacitors connected in series? Please go through the image once as my confusion lies there.
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2answers
56 views

Uniform Polarized Sphere - are there free charges? How to use Electric Displacement?

I'm studying EM for the first time, using Griffiths as the majority of undergraduates. So, in studying electric fields in matter, we derived equations for the volume and surface density charge of the ...
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3answers
109 views

Why do my books introduce the equation $\nabla \cdot \mathbf{E}=\frac{\rho}{\epsilon_0}$ without showing partial derivatives of $\mathbf{E}$ exist?

In electromagnetism (electrostatics), we often come across the equation $\nabla \cdot \mathbf{E}=\frac{\rho}{\epsilon_0}$. In order for this equation to be meaningful, $\mathbf{E}$ must be a ...
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0answers
34 views

A long cylindrical volume contains a uniformly distributed charge of density $\rho$. Find the flux due to electric field through the small cylinder [on hold]

A long cylindrical volume contains a uniformly distributed charge of density $\rho$. Find the flux due to electric field through the curved surface of a small cylinder whose axis is $OP$ and whose ...
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0answers
29 views

Is this deduction of the work done by an electrostatic field correct? [on hold]

Given an electrostatic field $\vec{E}$, the work done by the field when moving a particle with charge $q$ along the path $\Gamma$, can be expressed as $$ W = \int_{\Gamma} q \vec{E} \cdot d\vec{l} $$ ...
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2answers
56 views

Finding Electric field by using Gauss law [on hold]

A conductor sphere with radius r has charge distribution of Q = 12.0 μC. What is the electric flux away 2cm from sphere.
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0answers
36 views

Microscopic explanation for Hooke’s law

This figure shows the force between two atoms - at separation d there is no repulsive or attractive force, but for separation between d and the minimum, there is an approximately linear increase ...
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6answers
535 views

Why the work done is positive when bringing 2 opposite charges together?

we know that if the applied force is in the direction of the displacement then work done is positive.But in case of bringing 2 opposite charges from infinite to a certain distance,the work done is ...
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0answers
27 views

Use the method of images to find the potential $V(r)$ in the cavity [closed]

Here's a problem I'm stuck with. If the line charge is in the cylinder-shaped conductor, I'll know how to solve it by method of image.
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2answers
57 views

Interaction of an electric field of infinite length

Question: In a system which prodivides an electric field of an infinite length, if another electric field or particle interacts with it at a certain point, will there be a change at a point infinitely ...
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3answers
54 views

Why is the force required to keep a parallel plate capacitor EQ/2?

In our electrostatics course we were talking about how if you increase the separation of the plates by a tiny amount, then as the field is still constant, the potential difference increases. This ...
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4answers
1k views

Why is there no current between two capacitors connected in series?

I want to ask a question about the figure below. Why the current does not flow from $-Q$ term to $+Q$ term or from a to b since there is a voltage?
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2answers
39 views

Why the electric field on the surface of charged spherical shell of radius $R$ and charge $q$ is $\frac{kq}{R^2}$?

As we know the electric field at a point due to charge $q$ is equal to $\frac{kq}{r^2}$ where $k$ is the constant of proportionality and $r$ is the distance between the charge and the point (where we ...
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1answer
45 views

Is there even a slight transient current when a piece of wire is connected to a single terminal of a cell?

Suppose I have a cell/battery , both the terminals are at non-zero potentials.If I connect a piece of wire to say the negative terminal will there be some sort of electron redistribution in the wire. ...
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1answer
25 views

Interaction Energy in Electrocostatics [closed]

What is "interaction Energy " in Electrostatics? I came across this term when my teacher told me about the formula (e0)E²/2 where e0 is permittivity of free space So on calculating for 2 sherical ...
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0answers
8 views

Query about a dielectric rod touching a grounded conducting sphere

Here is the situation: A dielectric rod is has $q$ couloumbs worth of charge uniformly distributed across it. It comes in contact with a grounded sphere as shown above. The goal was to find the ...
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2answers
41 views

Is there a force between current-carrying parallel wires when the charges move with the same, constant velocity in each?

Let's assume that all charges flowing in both wires are either all positive or all negative. From the frame of reference of an individual charge in either wire, it would appear as if the position of ...
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1answer
17 views

Why cant a polar dielectrics molecules ever completely align with an applied electric field?

In my electro statics course my professor said that the molecules in a polar dielectric cant ever fully align with an external electric field as they will want to then 'turn back on one another', so ...
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0answers
21 views

Induced charges in Electrostatics

How to find the distribution of induced charge on conductor kept in a uniform electric field? Is there a particular method to do the same?
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3answers
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Problems in electrostatic [on hold]

Electrostatic is the branch of physics in which we study about charges at rest relative to inertial reference frames then how can the problems like electron revolving around nucleus be given in this ...
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1answer
48 views

Why does the electric flux through the surface of a cube with a point charge inside it remain unchanged when the point charge is moved? [on hold]

Why does the electric flux inside a cube remain unchanged when the charge is moved within the cube (not on vertices/faces/edges) but just in volume?
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0answers
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Charge projectile emanating Electric field [closed]

Two point changes +q and -q are separated by distance d .A particular electric field line emanating from charge +q at an angle of 60° attains maximum height h above line AB as shown. IF h = ((√x.)(d))/...
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1answer
36 views

Energy density in electrostatics - definition

Background: It can be shown that the potential energy of charge distribution can be calculated by $U = \frac{1}{2}\int_V \rho(r')\Phi(r') d^3r' $ by means of integration by parts and the poisson ...
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0answers
30 views

Problems in calculating potential of uniformly charged infinite plane or wire

From $\int_Vd^3x \rho(\vec x)\mathrel{\mathop{=}\limits^!}Q_V$ and by use of Dirac's delta distribution one finds that the charge density for the uniformly charged infinite plane is $\sigma\cdot\delta(...
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0answers
47 views

Static charge in an accelerated frame

In special relativity the metric of an accelerated frame is $$ds^2= (1-2 a_j x^j)dt^2 + 2 \Omega_{m j}x^j dx^m dt + \eta_{ml}dx^m dx^j$$ where the sums over latin indices go from 1 to 3. Let's suppose ...
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1answer
18 views

Repulsive force from charge accumulation in a capacitor plate?

During a charged state of a capacitor (Regardless of the type of capacitor), Simple parallel plate: .png Parallel plate with dielectric material in the gap: ]3 Supercapacitor: How is the ...
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3answers
40 views

Why is it that magnetic fields(or any field)not move in space? [on hold]

When I imagine a magnetic field produced by a magnet, or the electric field produced by a charge, I've learned that the fields are stationary, however, their value(across space) changes. If I placed ...
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1answer
52 views

Finding the maximum value of electric field

Suppose you have a surface of finite area with a fixed surface charge distribution. Does a maximum electric field magnitude $|\vec{E}|_{max}$ exist for each and every possible surface area? If yes, ...
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1answer
55 views

Intuitively understanding why the charge capacity of a conductive sphere depends on its radius , not its surface area

I am currently teaching to 9th grades. I tell them: Excess charges are always on the surface of a spherical conductor and I include that the charge capacity of the spherical conductor depends on its ...
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1answer
46 views

Does $Curl(E) = 0 $ along an equipotential sphere require that the radial component of $E =$ constant on the sphere?

I'm arriving at the conclusion that "$\nabla \times \vec{E} = 0$ on the surface of an equipotential sphere ($E_\theta = E_\phi = 0$) (as the field must be normal to an equipotential/conductor) implies ...
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1answer
52 views

Why is it possible to write the electrical potential as a sum of $\int dV \,\rho/R$ and $\int da \,\sigma/R$?

I'm trying to understand why one can write the electrical potential as follows \begin{equation} 4\pi\varepsilon_0\phi(\mathbf r) =\int d^3 r\,\dfrac{\rho(\mathbf r')}{\|\mathbf r - \mathbf r' \|} + \...