A fundamental property of matter which causes it to experience electromagnetic forces.

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Why is the potential energy of a dipole in an electric field zero when the dipole points perpendicularly to the field?

I have read that potential energy of a dipole in an electric field is taken to be zero at 90 degree as they say that it is a reference. But there must be some reason behind it?
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1answer
28 views

Electric field uniform circle $R$ direction cancel out

I am doing a physics problem involving a uniform circle with a total charge of X, and am attempting to find the electric field on a point charge on the axis of the circle a distance of Z away. I ...
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2answers
33 views

Finding Charge given Electric Field

This question came up in a competition, and I didn't know how to solve it. ABCD is a rectangle with width $2d$ and height $d$. At point D, there is a charge with magnitude $q_1$ At point B, there ...
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2answers
129 views

diffusion velocity

i understand that diffusion is the movement of particles from high concentration areas to low concentration, but what is the cause of that movement atomically. And especially in the case of charge ...
2
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2answers
403 views

Maximum limit of charging a capacitor

We say that we can charge a capacitor in proportion to the potential difference we apply across its plates and the maximum potential difference depends on the dielectric strength of the medium. Now ...
4
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1answer
96 views

Is it possible to push together two charged particles of the same charge hard enough so it becomes a black hole?

My chain of thought is the following: To push together two charges of the same sign you need to do work. The energy spent will be turned into electrostatic potential energy. Can we pump so much ...
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2answers
175 views

Why is charge constant in series connections?

Why does each capacitor in a series connection hold the same charge? I understand that voltages and capacitances across capacitor plate pairs in series vary, but why is it a necessity that charge be ...
2
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1answer
76 views

Balloon and Static Electrcity

I am learning about charge, but there is one thing I don't understand. In the above picture, I understand that the balloon sticks to the wall because of the attraction between the negative charge ...
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1answer
106 views

What does electrically charged mean?

So I was reading my physics textbook and it said that "Suppose we have two metal spheres, one highly charged and the other electrically neutral." What does it mean by highly charged? Does that mean ...
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1answer
202 views

Method of image charge for cylindrical conductor

I am simply puzzled that only for spherical and planar conducting surfaces the method of images is applied. Is it (really) impossible to find image charge or charge distribution which can simulate the ...
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1answer
227 views

How charges can be at rest if there is a force on it?

Electrostatics deals with forces between charges at rest. But if there is a force on a charge, how can it be at rest? My guess is that charges is being kept at rest by some unspecified forces that ...
2
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1answer
436 views

What is Gauss's Law in two dimensions?

I am trying to figure out how the equation for the field if a Gaussian surface was applied to a 2D plane. I did see another question already asked on the subject, but I didn't get a particular ...
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0answers
97 views

Relationship between electric field and distance

I am working on a lab report that asks a conceptual question related to one of the labs we did on electrostatic fields. For the context of my question, here is how the experiment is set up. We have ...
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1answer
66 views

Calculating the rate of electrostatic discharge via current density

After I asked this question, with the help of Floris' comment, I tried to learn more about the concept of current density and tried to calculate the current density in my scenerio which, it seems, is ...
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0answers
89 views

Derivation Electric force

I’m a physics of high school (SMAN 3 Bandar Lampung, Lampung, Indonesia 35116). I make the experimental apparatus in static electric field. Instrument arrangement in the image below: The theoretical ...
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1answer
97 views

Deriving the Lienard-Wiechert Potentials

Let $\mathbf{w}(t)$ be the trajectory of a moving charge. Let the observation event be $(\mathbf{r},t)$. The scalar potential is: $$\varphi = \frac{q}{4\pi\epsilon_0}\int \frac{\delta\left(\mathbf{r'...
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2answers
116 views

Is Quantum Coulomb still singular?

A single free charge (e.g. electron) $q$ fixed at the coordinate origin has the well-known Coulomb/electric potential $$\phi(\vec r) = \frac q{4\pi\epsilon_0}\frac 1r \tag{A}$$ where $r=|\vec r|$ of ...
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1answer
41 views

prototyping a cyclotron , a charging problem

I'd like to model a cyclotron but not with subatomic particles but with a small metallic ball but the problem is i need to charge the metallic ball with certain amount of charge and i must know it to ...
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1answer
274 views

Finding the electric field at a point from half of a uniformly charged rod

The image below is a rod of length that is uniformly charged to total charge at a point along the perpendicular bisector of the rod above distance . I know the formula for finding the electric ...
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0answers
55 views

Can you calculate the charge after rubbing two objects

If there are two insulators and you rub them together for a long time, is there a way to calculate how much charge should have transferred between them. I'm sure there is some relation to the ...
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1answer
92 views

Charging identical spheres using induction

Suppose I can induce a charge Q in a conducting sphere by the traditional induction method, then why is it that the charges would be equally shared if I put this sphere in contact with another ...
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4answers
210 views

Why, fundamentally, are particles charged?

This is something that has long bothered me, and I have asked a few physicists and chemists and never gotten a very satisfying answer. Why are particles charged? And I'm not asking (and this is the ...
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2answers
182 views

How to determine the angular velocity of a particle with mass $m$ and charge $q$ in a constant B field? [closed]

$\textbf{PROBLEM:}$ A particle with mass $m$ and charge $q$ moves in a constant magnetic field $B$. Show that, if the initial velocity is perpendicular to $B$, the path is circular and the angular ...
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0answers
66 views

Electric field radiation with moving charge and observation point

I've been working on Chapter 34 of the first volume of the Feynman Lectures on Physics http://www.feynmanlectures.caltech.edu/I_34.html#Ch34-S1. In Fig. 34–3 (reproduced above) Prof. Feynman shows ...
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1answer
35 views

Help with this question (Eletric Fields, Dipole) [closed]

The answer in the textbook in the solutions manual is the following: I didn't undestand the last step. He said he did a binomial expansion, I just can't figure out! Appreciate any help.
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1answer
33 views

Putting an Electron on a Conducting Sphere [closed]

What all might go on inside a conducting sphere if I (try to) dump an electron upon it?
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1answer
73 views

Is it possible for a conductor initially, not to have a charge?

Well I'm confused. The thing that was implanted to me is that when I hear about conductors, some charge is present and it can move freely. Now what I want to know is that is it possible for a ...
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2answers
492 views

Why do charged objects attract pieces of paper, but not pieces of metal?

I do not understand one concept in Physics: why charged objects (eg. a charged rod or comb) attract pieces of paper when brought close to them, but do not attract pieces of metal. I know that the ...
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1answer
136 views

Levitating capacitor

As the title already says, I would like to make a large capacitor levitate. Before you dismiss this question please hear me out: In essence, this is intended to be a way to avoid the constrains of a ...
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2answers
132 views

The source and sink phenomenological description of charge - how realistic is it?

I've heard over and over an electron described as a source of the electric field, but that is a misleading term. Source makes one thing of a tap, with a constant flow of something coming out of it. ...
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2answers
170 views

Why do we get electric shocks when most structures are insulators?

Suppose I was standing in the sea, and touched an electric fence; I would receive an electric shock, because both my body and the sea are conductors, and create a path for the electricity to flow. The ...
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0answers
63 views

Will charge transfer without friction

I know rubbing two objects of different materials together will result in a negative charge on whichever material has a higher electron affinity. However, I was wondering if a negatively charged ...
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1answer
63 views

Simple question regarding Gauss's electric law

I just read that electric flux=enclosed charge/permittivity. Considering the charge in an enclosed surface is always 0, what is the point in even having this equation? Or is the equation actually ...
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1answer
225 views

What will be effects of harnessing lightning?

In Feynman's Lectures, volume 2, chapter 9, there is a mention of earth getting charged by thunderstorm lightning. It is the thunderstorms throughout the world that are charging the earth with an ...
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1answer
137 views

Why cannot massless particles carry charges? [duplicate]

How to show that massless particles do not carry charges from QFT's point of view?
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1answer
48 views

Can we charge any two bodies (insulators) by rubbing?

I am not talking about the usual glass rubbed with silk rather any two insulators found in nature. If we rub them, will they get charged? Like cotton and plastic etc.
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1answer
55 views

Why does flux in closed surface remain constant if exterior charge is altered?

Q. Charges $q_1$ and $q_2$ lie inside and outside respectively of a closed surface $S$. Let $E$ be the field at any point on $S$ and $\Phi$ be the flux of $E$ over $S$. One of the answer is: if $q_2$ ...
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4answers
233 views

Voltage - Energy drop

I'm having a hard time understanding the nature of voltage and am hoping you guys can help. The main issue is the concept of the voltage drop. Take the following circuits : In regard to the first, ...
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3answers
243 views

Drawing the lines of force for an electric field varying in magnitude but having a constant direction

How will the electric lines of force look for an electric field varying in magnitude but having a constant direction, say along +ve z axis ? According to me, since the electric field is varying in ...
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1answer
74 views

Capacitor and Pith Ball experiment

Suppose I first charge a capacitor so that one plate is positively charged and another negatively. Now I remove the charging source and ground only one of the terminals say negative terminal, will ...
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2answers
1k views

Rate of flow of electrons in a simple circuit, given the current? [closed]

I have this question: The correct answer is C. I understand that the flow of electrons should be from Y to X because electrons flow opposite to "conventional current", which is from positive to ...
1
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1answer
31 views

Surface charge on a straight region of a conductor

Most physics textbooks and even questions in stack exchange answer the question why there exists a charge buildup in the bends of a current carrying conductor. But what I am unable to understand is: ...
3
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2answers
210 views

Force on non-moving charge in solenoid with increasing magnetic field

The problem: "Through a solenoid there is an increasing magnetic field $B$. For a positively charged particle not in motion, what is the direction of force on the particle?" Normally a non-moving ...
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1answer
79 views

Charge of $W$-bosons in Feynman diagrams

When looking at Feynman diagrams of particle decays, how would I be able to find out the charges of the $W$-bosons involved in the decay?
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2answers
40 views

Is this diagram in my textbook not constructed to scale?

Or am I having an illusion. Clearly, the distance from 6v to 4v is not the same as 4v to 2v. I know it should be based on: $V = k\frac{q}{r}$.
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1answer
89 views

How does the size of conducting sphere affect the distribution of charge?

I am doing my homework. One question gives individual charges on two spheres. And asks what the resulting charge is on each after touching. But one thing interest me is that in the answer key, it's ...
0
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1answer
46 views

Why can't objects made of insulating material “store excess charges”?

This is quoted from my textbook. I saw plastic objects before being able to store excess charges. For example, if you rub paper against a plastic pole. Both will gain charges. But in lab, I never ...
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1answer
27 views

Would an electroscope work if it were not in a glass container?

I'm reading about the gold-leaf electroscope and all the sources I've read show that the gold leaves are placed in a glass container. Is there something special about the glass, or would any container ...
2
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2answers
315 views

Principle of superposition and QED

For finding a net force on a charge when it is in influence of many charges we simply do vectorical addition of all individual interaction of that charge with others. That's what is principle of ...
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1answer
128 views

What are the interpretations of ampere's circuital law for a single moving electron?

I understand from Ampere's circuital law that when a current passes though any open surface with a boundary (a circular boundary, for simplicity), then limit of summation of the scalar products of ...