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-...

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Work done by battery and potential energy of a capacitor

I have a doubt about the work done by a battery and the potential energy of a capacitor? 1- Consider a circuit where the capacitors are connected to the terminals of a battery. Through calculations ...
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4answers
677 views

How would you define electrostatics and magnetostatics starting from Maxwell's equations?

I'm reading Griffith's text, and he starts by defining Electrostatics as requiring the source charges don't move. I've seen a few slightly different definitions of electrostatics and magnetostatics. ...
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0answers
35 views

Determine potential function given initial conditions?

Assuming a radially symmetric circular disk (let's say r=1). Given two simple initial conditions: Potential at the centre is 4 V Potential at the edges is 0 V How would I determine the potential ...
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2answers
58 views

Why electric potential at equatorial point of a dipole is 0?

Well ok I know that electric potential at equatorial point of a dipole is 0. It is a derived conclusion. Q1. But how this can be explained "theoretically"? Another question that electric potential ...
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1answer
15 views

Relyance of plate distance on the capacitor equation

I am studying capacitors and i cannot seem to understand why the increase/ decrease in voltage and distance between the plates would affect the capacitor's abillity to store charge. Can anyone help??
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0answers
26 views

AP Physics 1/2- Electrostatics Capacitor [closed]

I recently took a physics exam over Electrostatics Capacitor and was unsure about a couple of questions. the test was free response and I had to explain. Please tell me if my answer and reasoning ...
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0answers
27 views

Is it possible to get an analytic expression of the capacitance for this geometry?

Here is the geometry I'm talking about: Assume the red rectangle is at some constant potential V, like 10 Volts, and the blue is at ground. We can assume that the rectangles extend infinitely (to ...
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0answers
12 views

Charges on outer faces of parallel plate capcitor

Can there be charges on outer charges of a parallel plate capacitor if both the plates are initially charged by different amount and then connected with a battery.
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1answer
240 views

How does EM radiation depend on the reference frame?

In special relativity, magnetism is electrostatics in a different reference frame. This is how we explain the magnetic field being produced by moving charges (aka currents). Charges that move produce ...
3
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1answer
259 views

What causes charge buildup in a cloud before a lightning storm?

I am curious what causes the charge build up in a cloud before lightning occurs. I have seen in a few places such as this, that the process is not fully understood. Is this some form of static ...
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0answers
40 views

Time of free fall in a repulsive force [duplicate]

The formula for time of a free falling body when acceleration is not constant can be found in any answers here at this site and also at wikipedia. But I haven't been able to find any formula for a ...
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0answers
27 views

Static field on plastic slide only during day not night

Can anyone fully explain why- A modern kids park play ground slide made of plastic has a static field of electrons gathered on it only during the day and never at night?
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1answer
37 views

Field due to induced charges in and out of a conductor with a cavity that contains a charge inside

I want to know the proof for the following statement:- The net electric field due to the "induced charges on the surface of the cavity and the charge inside the cavity" is zero everywhere outside ...
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4answers
176 views

Electrostatics and two electric charges [closed]

How can two identical metallic objects have the same but opposite charges (one loses electrons and one gains electrons) when we know that metals have the ability to lose electrons only?
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2answers
50 views

Calculating charge density $\rho(r)$ using Gauss law (both forms)

Below is a question given in my assignment. I tried applying Gauss law in both forms, differential and surface integral form. But both there is a difference by a factor of $2$. Is the differential ...
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0answers
16 views

The distribution of net charge in the Millikan oil drop experiment?

What is the distribution? Of course it depends on the concrete setup. But, what is the typical value? The concern is that, if the distribution is peaked at, say 1000, it would be very difficult ...
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0answers
37 views

Does wearing a metal hat does increase your chance of being struck by lightning?

Does wearing a metal hat does increase your chance of being struck by lightning? Prompted by this video. My view is that it makes no difference as to the conductivity of the head or the field ...
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2answers
45 views

Zero electric field in empty region of hollow conductor

A hollow conducting shell having a net charge of +Q has a point charge -Q placed at its centre. From the diagram, it looks like Suppose the radius of the inner shell from the origin is a and the ...
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1answer
24 views

Poisson's equation for conductor with non uniform conductivity

In my introductions to electromagnetics course we have a computer lab where one of the preliminary question is as follows (my attempt at an answer is below the bold part): Is my reasoning correct? ...
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0answers
31 views

Grounding system of conducting plates

So, I always make mistakes on problems such as this (the grounding part), so I'm hoping someone could really explain to me how the process works . There are n large parallel plate conductors carrying ...
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1answer
29 views

How to obtain $2\pi\epsilon_0$ when computing capacitance per unit length of a system?

To make my question more clear, I will use an example to illustrate it. Consider an infinite conducting plane, with a long conducting cylinder of radius $R$ at a distance $h$ away from it, with the ...
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0answers
25 views

The velocity of the charged particle in the magnetic field [duplicate]

Enrico Fermi considered that moving charged particle gains energy in the magnetic field, so its velocity increases. According to the Lorentz Law $\vec F=q\vec v\times\vec B$. Work is $A=\vec F\times\...
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1answer
41 views

Maximum electric field of a circular ring

How do you differentiate the equation for electric field of uniform ring $$ E_x = \frac{kxQ}{(x^2+r^2)^{3/2}} $$to get the maximum at a point? My book says $x = \frac{r}{\sqrt2}$. I tried ...
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3answers
754 views

How to find the distribution of charge on two spheres connected by a conducting wire?

A solid metal sphere of radius $R$ has charge $+2Q$. A hollow spherical shell of radius $3R$, concentric with the first sphere, has net charge $-Q$. What would be the final distribution of the charge ...
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3answers
117 views

How does the Electric Field create a force? [closed]

If we have 2 charged particles which are a certain distance away from each other, they either attract of repel due to the electric field created by both of them. But I don't understand the mechanism ...
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0answers
21 views

Electric field of an infinite plane (with and without an infinite conductor)

Suppose we have an infinite and uniformly charged (of surface charge density $\sigma \gt 0$) plane at $z = 0$. We can find the electric field at any point $(x, y, z)$ by computing an integral all ...
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2answers
50 views

Why is the electric potential zero in this case?

The situation: a charge of $-2q$ is situated a distance $r$ to the left of a charge of $q$. What is the electric potential at a point $p$ a distance $r$ to the right of charge $q$? So basically: -2q -...
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1answer
85 views

What did Feynman want to mean by 'artificial energy'?

I was reading Mechanical and electrical energies by Feynman when I came before this: We have seen an analogous situation in electrostatics. We showed that the energy of a capacitor is equal to $Q^...
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1answer
31 views

What does potential mean in capacitor?

Technically potential means work done to move a unit positive charge from one point to another against electrical field but What does potential mean in a capacitor?
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7answers
273 views

Is the electric field of a volume charge distribution well defined?

Consider a volume charge distribution $\rho({\bf r'})$. The electric field at ${\bf r}$ is $${\bf E}({\bf r})=\iiint\frac{1}{4\pi\epsilon_0}\frac{\rho({\bf r'})}{R^2}\hat{\bf R}\, \mathrm d^3{\bf r'}$...
3
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4answers
3k views

Charged particle between two parallel likely charged plates, is it affected by the plates?

Imagine two parallel conductive plates. Charge up both to have the same amount of positive charge. Then put positive test particle between the two. The Coulomb's law is an inverse square law, so one ...
-1
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1answer
28 views

Electrostatics, System of Charges [closed]

At $t=0$, a positive point charge of mass $m$ is projected toward another positive point charge of mass $m$ in free space. At the instant of minimum separation kinetic energy of the system of two ...
0
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1answer
35 views

Why don't conductive objects change color when electric dipoles are induced in them?

I was playing around with a comb, my hair, and pieces of paper when it occurred to me that inducing a dipole on the pieces of paper meant that many valence electrons previously on the side closer to ...
2
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2answers
54 views

Filling a charged capacitor with dielectric material

If there is a charged capacitor (capictance $C$) connected to a battery (of EMF $V$) and the space between the plates of the capacitor is filled with a dielectric material (dielectric constant is $K$),...
0
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1answer
44 views

Electric Flux in a Cube [closed]

Suppose there are 2 cases: A hollow cube with a point charge $+q$ at the center of one of the faces A hollow cube with a point charge $+q$ at the midpoint of one of the edges. In case 1, the ...
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0answers
19 views

Which is the form of Born-Mayer repulsion term?

I have found in many textbooks different and unclear form of the Born-Mayer repulsion term. I write the interatomic potential as $V(r)= -\frac{e^2}{r}+V_{BM}$ and for $V_{BM}$ I expected something ...
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4answers
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0
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3answers
65 views

How to apply Gauss law at null points?

How do I use law to determine total flux at Gaussian surface at null point? It seems , when I consider a Gaussian surface around null point, two axial electric field lines enter it but they don't ...
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1answer
55 views

Integrating by parts [closed]

I am having little trouble with my professor's note. $$F=-\int{(dr)}{(\vec{\nabla} \cdot \vec{P}) \vec{E} }=\int{(dr)}{(\vec{P} \cdot \vec{\nabla} ) \vec{E} }$$ where F is force, P is polarization, ...
0
votes
1answer
53 views

When two like charges are placed at a large distance from each other, do they attract each other? [closed]

So my friend and I were arguing about this. He insists that if two like charges are placed at a large distance from each other, they attract each other. I find this nonsense. This clearly violates ...
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0answers
12 views

Electric displacement and Field

Given a problem with dielectric constant value in a region and asked me to find Electric Field and Electric Displacement inside the medium, Should I calculate E first or D first?
0
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1answer
26 views

Magnitude of charge on each plate of a parallel capacitor? Why should I multiply by two?

Here's the full question: A parallel-plate capacitor has a plate area of $0.2\ \mathrm m^2$ and a plate separation of $0.1\ \mathrm{mm}$. To obtain an electric field of $2.0\ 10^6\ \mathrm{V/m}$ ...
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2answers
48 views

electrical field in coaxial cable

When getting the electric field between the outer and inner cylinder. why is it that we are only concerned with the field generated by the positive charge distribution on the inner surface and not ...
0
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0answers
41 views

Frequency of Electromagnetic Radiations/Waves?

"A charge that is accelerated will produce variable electric and magnetic fields. These are electromagnetic waves. If the charge oscillates with a frequency f, then the resulting EM wave will have a ...
-1
votes
1answer
27 views

What is the electric field at the midpoint of the hypotenuse of a triangle? [closed]

Given, AB = BC = a and Charges at A, B and C are +q, +2q and +q respectively. Found this problem in a textbook. I did it this way : Charges at A and C will have no effect at this point since electric ...
-2
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0answers
19 views

There is a hollow object where will the charges reside? Inside the balloon or on the surface of it? [duplicate]

There is a hollow object (for example an inflated balloon.it is charged. where will the charges reside? Inside the balloon or on the surface of it?
1
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3answers
68 views

how could Kinetic energy increase if no energy was there in the system?

i was reading Physics-Halliday, Resnick, Krane(fifth edition) there on page 638 it is written: if the external agent does positive work in assembling the charge ...
0
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1answer
42 views

Principle of capacitor

It is said that second conductor reduces the potential of fist conductor and hence increases charge taking ability of first conductor My confusion... As per my limited knowledge it is electric field ...
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1answer
52 views

Magnetic force on a charged particle doesn't affect total energy

So there's this sentence in a book I am reading. It states "When a charged particle is placed within a magnetic field, despite the magnetic force acting on the particle, there will be no change in the ...
1
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1answer
309 views

How to draw equipotential surfaces for a dipole or system of two like charges?

How can we draw the equipotential surfaces (i.e the surface which has constant potential on all its points) for an electric dipole and a system of two like charges? I read it in some book that they ...