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

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181 views

Potential difference of conductor with induced load

If a metallic sphere is grounded and close to a positive charge q, it will be charged with -q. Let's say that the electrons will arrive through the grounding. This charge will cover the surface of the ...
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1answer
106 views

Efficiency of an electric motor? [closed]

Question: An electric motor runs off a 12V d.v. supply and has an overall efficiency of 75%. Calculate how much electric charge will pass through the motor when it does 90J of work. Can someone tell ...
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1answer
133 views

Capacitors and Voltage

Imagine if I have a capacitor, connected to a battery of $12 V$. After charging the capacitor, I increase the plate separation. Then my capacitance decreases, right? But charge should be ...
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0answers
36 views

How can a black hole have a charge? [duplicate]

Under current particle theory, the four fundamental forces use a force-carrying particle. The particle for electromagnetism is the photon. By definition a black hole is a mass from which light can ...
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2answers
155 views

Current in discharging capacitor through fixed resistor?

In the textbook I'm using for physics it says that the charge left on the plates of a capacitor after time $t$, that is discharging through a fixed resistor, is $Q=Q_0e^{-t/\tau}$ where $\tau=RC$ is ...
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1answer
55 views

Question about particles in electric fields. Homework question

I am currently working on a homework question and I realized that I don't really understand some of the material that we covered so I hoped that you guys can help me clear up some misunderstandings. ...
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3answers
2k views

Do quarks violate quantization of charge?

Does existence of various kinds of quarks like up, down, strange, charm, top, bottom violate the quantisation of charge or just redefine it as up quark have charge +2/3 and have -1/3. Or do things get ...
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2answers
54 views

How does magnetic field affects a charge?

If a electron is placed in a fixed magnetic field, how the electron will get influenced by it? How does magnetic field attacts/repulses the charge?
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1answer
358 views

Fleming's left hand rule

in Fleming's left hand rule is the direction of current showing the direction of the flow of electrons or the direction of positive charge?
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2answers
289 views

Conducting rod moving through magnetic field

If a conducting rod moves through a magnetic field which way do its electrons move? In my revision guide it shows the following picture (more or less, but the following is my drawing of it -- I ...
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2answers
182 views

How does electron gets negative charge and proton gets positive charge? [duplicate]

I researched much in physics but I still do not know how does electron gets negative charge and proton gets positive charge? What is the source of this charge and energy? How can this particles ...
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1answer
60 views

When a capacitor finishes charging

When a capacitor is fully charged I usually hear the phrase "the potential difference across the capacitor opposes the battery potential difference, so no more charge flows". What does "the potential ...
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1answer
224 views

Charging a capacitor (terminals)

When a battery is connected to a conductor electrons are repelled from the end of the conductor connected to the negative terminal of the battery and flow to the end of the conductor connected to the ...
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1answer
77 views

Typo in physics book (capacitors)

I'm currently working through an AP revision guide. The section on charging a capacitor outlines the following steps: When a capacitor is connected to a battery, a current flows in the circuit until ...
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0answers
23 views

Integrating Charged Bodies

Why is it possible to integrate charged bodies by first taking a small charge and adding more small charges around it? Wouldn't the similarly charged particles exert an immense amount of force on ...
0
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1answer
51 views

Why is charge = nALe

Sorry if this question is a bit broad but I can't find any info on this by just searching. The equation q = neAL where L is the length of a conductor, A is the area of cross section, n is the number ...
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2answers
270 views

How does electromagnetic radiation affect the velocity of a charged particle?

I've heard that the acceleration of a charged particle releases electromagnetic waves. So let's say there is a charged electron moving forwards in a region with a downwards magnetic field. If the ...
2
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1answer
106 views

Why do nuclear bomb explosions create an array of visible electric discharges in the form of lightening in the upper atmosphere?

I've seen videos on the internet, showing nuclear bomb test explosions, and there appears to be a large amount of visible lightening discharging numerous times over the development of the mushroom ...
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3answers
123 views

Path followed by a free test charge in an electric field region represent the electric lines of forces?

As we know that if we put any free test charge in an electric field which is moving horizontally then it will experience an repulsive force and move in that direction so by that we can say that for ...
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1answer
70 views

Classical Hydrogen Atom

I was wondering about the Hamiltonian description of the classical hydrogen atom (two point particles interacting through a Coulumb potential). In particular, I want to know if the fact that ...
2
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1answer
253 views

Charge conservation in the complex Klein-Gordon Field

This is an extremely naive question (based on a knowledge of chapter 2 of peskin and schroeder) so apologies for any things that seem obvious. The complex scalar field, when quantized, has a conserved ...
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0answers
83 views

Calculating the electric charge of two spheres knowing their potential

I have a system of two spheres, the first one is at a potential of $ V_1 = 1 V $ and the second one is at a potential of $ V_2 = 0 V $ The distance between them is $d$ and the radius are respectively ...
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1answer
43 views

Is battery the supplier of charge in an electric circuit?

In a simple electric circuit consisting of wires, battery and a bulb... Are the charges which flow in the circuit provided by the battery or are they coming from somewhere else?
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1answer
137 views

Potential of a sphere induced by a charged sphere

I am trying to solve what seems like a simple problem but something is bothering me: Imagine we have a sphere (1) with a charge $Q_1$ and at a distance $d$ we have another sphere (2) which is a ...
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1answer
78 views

Does elementary particle emit photon?

Charged particles are accelerated by the magnetic field in a particle collider before allowed to smash together at specific location where the detectors are housed. My question is do the ...
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2answers
76 views

Removing the charge from charged object

let's say I have an object with an electric charge Q. I'm not sure if I can remove charge 2Q from it so it will become negative (-Q) or I can't do it. To be specific I have this example: There are two ...
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1answer
114 views

What's difference between C parity and charge?

I know C parity as an operator : $$ C\psi=\pm\psi $$ has two eigenvalues like parity operator P. But what I wonder is, i.e, is it true to say for a negative charged particle has (-) eigenvalue? If not ...
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2answers
615 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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90 views

Does lightning have a thickness?

We have calculated (probably measured) the speed, temperature and voltage of lightning so does lightning have a thickness? Note: When a lightning occur it heats up the air rapidly causing the air to ...
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5answers
219 views

Why is charge of the electron negative?

How did scientists figure out that the charge of the electron was indeed negative? I know how the cathode ray tube experiment works, but how did Thompson know that the plate that the cathode ray beam ...
2
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2answers
246 views

Considering this hypothesis…is charge really quantized? [closed]

[If anything goes against any mathematical or physical rules please let me know. I am a first year undergraduate student perusing a joint major in mathematics and physics so I do not have a complete ...
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2answers
159 views

Force when distance between charge is zero

According to coulomb law $$ F = \frac{q_1q_2}{r^2} $$ I want to know what happens to force when $r=0$. If $F \to \infty$ then the charges can't be separated! But if an unlike charge of higher ...
2
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1answer
122 views

Physical interpretation of single layer potential in the plane

Let $\Omega\subset\mathbb{R}^2$ be a bounded domain with smooth boundary $\partial\Omega$. The single layer potential with charge density $f$ sitting on $\partial\Omega$ is defined by ...
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2answers
2k views

Direction of electric field lines and electrostatic force

Direction of electric field and electrostatic force should be same by the equation $$\vec{F} = \frac{k q q_0}{r^2}$$ Electric Field $$\vec{E} = \frac{k q}{r^2}$$ Let us suppose that there is a ...
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1answer
78 views

Charge of a moving particle [duplicate]

Is there an experiment that measures the electric charge of a moving particle, therefore proving "experimentally" that it is indeed the same as a static particle?
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2answers
488 views

Checking for equilibrium in a square configuration of charges [closed]

Four equal positive charges each of magnitude q are placed at the respective vertices of a square of side length l. A point Q is placed at the centre of the square. Then find the state of equilibrium ...
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2answers
114 views

What actually is a continuous charge distribution? [closed]

I am well aware of the maths of how to do all sorts of calculations using continuous charge distributions (like volume, space, and, line charge distributions) but when I think about it I couldn't get ...
1
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1answer
103 views

Calculating charge density

When calculating uniform charge density, I yielded a solution with units: $$VC^2 / Nm^2$$ The answer is telling me that this is equivalent to: $$C/m^2$$ where: $$m : meter$$ $$C : Coulomb$$ $$V : ...
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1answer
42 views

Charge loop corrections

Let's assume some theory in which there is some gauge group (spontaneously broken) field $B$ and fermion field $b$ which isn't charged under this group, and this statement must hold for each order of ...
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1answer
98 views

Potential Difference between 2 points in a curcuit

3 Cells and 3 capacitors are connected as shown in the diagram. What is the potential difference between points A and B ? What are the final charges on each of the plates of the Capacitor ? Does the ...
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3answers
133 views

IF I touch anything at 0 volt with my hands and touch earth, will I get shock? Will charges from earth pass through me to 0 volt?

I know we don't get shock when we touch earth because we don't have anything to pass current to. What about when we touch 0 volts?
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1answer
156 views

Electrostatics and tv screens

My physics textbook states an activity- "Cut out thin strips of paper and lightly iron them. Take them near a TV screen or computer monitor. The strips get attracted to the screen and may cling to the ...
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1answer
107 views

Why can we ignore self energy?

I have been doing some practice questions in a text book [Electricity and Magnetism by Purcell and Morin]. So I know that the energy the potential energy of a system is the total work required to ...
0
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1answer
206 views

Final charges on Capacitors connected in a curcuit

Capacitor C1 is charged to a Potential Difference of 10V. It's capacitance is 2 microFarad. Capacitor C2 is charged to a Potential Difference of 15V. It's capacitance is 4 microFarad. Now the ...
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0answers
24 views

Galerkin-type weak formulation for electrokinetics

I am currently working on finite element simulations about electrokinetics. My solver (getdp) accepts directly galerkin-type weak formulation of equations. I am thus trying to write my equations in ...
0
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2answers
660 views

What does grounding a plate mean happens to the charge?

In the context of image charges. Let say I have a very large grounded/earthed plate. If initially the total charge on the plate is 0 then we place a positive point charge, $Q$ just above its surface ...
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0answers
82 views

Weizsäcker–Williams approximation

I'm having some trouble understanding the Weizsäcker-Williams approximation What I think it is is the following: I have a charged particle at high speed, close to the speed of light, at this speed ...
3
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2answers
138 views

Question regarding Van De Graff generator Belt

I have made a VDG generator with a rubber band as the belt and a glass roller. It doesnt seem to work because I think the rubber band may be conductive. I was thinking of using other materials for ...
0
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1answer
81 views

Can we create a electric field without actually using a battery or power source?

Can we create an electric field without actually using a battery or a source of electricity? Like a take 2 panels, one is positively charged and another is negatively charged and put them parallel to ...
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2answers
301 views

Continuity of Potential of an electric field

Consider a point charge $q$ at $(0,0,0)$, the potential at $\bf{r}$ is given by $V(\bf{r})$ $= \frac{q}{4\pi\epsilon_0r}$. If you consider a path through $(0,0,0)$, you encounter a discontinuity in ...