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

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How does positive charge spread out in conductors?

I know that when there are excess positive charges in a conductor, for example, a metal sphere, the positive charges will spread out over its surface. However, I am confused about how this excess ...
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2answers
98 views

If a particle is a point of high intensity in a quantum field, how can it have charge?

The charge of a fundamental particle is a mysterious but obvious and well-known property of every non-neutral particle. I can understand how, if a particle is an object, or thing, for want of a ...
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3answers
1k views

How is possible for current to flow so fast when charge flows so slow?

How is possible for current to flow so fast when charge flows so slow? We know electrons travel very slowly while charge travels at ~the speed of light.
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3answers
895 views

Why can we use Gauss' law to compute electric field?

For simplicity I'm considering only the sphere case. In the Gauss' Law formulation we have some field $E$ introduced by charges $Q$ inside some sphere, then we compute flux and integrate, and we get ...
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2answers
4k views

What happens to capacitor’s charge when the plates are moved further apart?

In my physics textbook there is an example of using capacitor switches in computer keyboard: Pressing the key pushes two capacitor plates closer together, increasing their capacitance. A larger ...
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1answer
76 views

Permanently charging a sphere by induction using a high voltage

I want to charge a sphere using a van de graff generator , it would sound easy , but using a 1 MV or a 900 KV is really hard, it is enough to break like 1 meter of air so whenever i try to ground the ...
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2answers
109 views

Was the fractional model of quarks electric charge found before discovery of the $\Delta^{++}$?

From Wikipedia: Existence of the $\Delta^{++}$ , with its unusual +2 electric charge, was a crucial clue in the development of the quark model. the fractional model of Quarks electric charge was ...
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2answers
100 views

Ashcroft Mermin Eq. 17.47ff

In "Solid State Physics" by said authors, Eq. 17.46 is $$ \rho^{ind}(\textbf{r}) = - e[n_0(\mu + e\phi(\textbf{r})) - n_0(\mu)]$$ and then the authors write In the present case we assume that ...
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1answer
136 views

Charged plane in an electric field acceleration

A perpendicular plane to an electric field's lines of force has more electric flux than a plane that is in parallel with the lines of force, right? Does this mean that a charged plate would ...
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1answer
175 views

Electrostatic charge leakage

What are the ways electrostatic charged objects leak charge in humid conditions? Can airborne particles pick up charge by contact, then be repelled hence removing charge? If so would it be a ...
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1answer
369 views

Electric Fields

The problem I am working on is, "In the figure below, determine the point (other than infinity) at which the electric field is zero. (Let $q_1 = -2.45\ \mu C$ and $q_2 = 6.5\ \mu C$) Here is a little ...
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1answer
524 views

Electric Field due to a charged sphere

Suppose we have a spherical surface with a surface charge density varying as $cos(\theta)$. Apparently one can find the electric field both outside and inside such a spherical surface by superposing ...
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1answer
269 views

Conservation of Energy as Applied to Point Charges

The following question appears to be extremely straight forward, but I can't seem to be able to obtain the correct answer. The question is: A charge Q1 = 1.3uC is at rest and is located 2.3 cm ...
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2answers
119 views

Is there a limit to the charge of a body?

Can a body be limitlessly charged? Suppose a sphere of radius $R$. Can it be charged limitlessly?
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1answer
38 views

Are the ions in a fluorescent lamps concentrated near the electrodes?

Are the ions in a fluorescent lamps concentrated near the electrodes , and just the electrons move to the other electrode or the positive mercury ions move too?
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1answer
4k views

What defines the maximum charge a capacitor can store?

The formula for a capacitor discharging is $Q=Q_0e^{-\frac{t}{RC}}$ Where $Q_0$ is the maximum charge. But what property defines the maximum charge a capacitor can store? If it depends on ...
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1answer
671 views

( Legendre Generating Function) Off axis Electric Potential from an insulated disk

An insulated disk, uniform surface charge density $\sigma$, of radius $R$ is laid on the $x,y$ plane. Deduce the electric potential $V(z)$ along the z-axis. Next consider an off axis point $p'$, ...
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1answer
746 views

Noether theorem and classical proof of electric charge conservation

How to prove conservation of electric charge using Noether's theorem according to classical (non-quantum) mechanics? I know the proof based on using Klein–Gordon field, but that derivation use ...
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3answers
1k views

What does a subatomic charge actually mean?

I was recently reading a popular science book called The Canon - The Beautiful Basics of Science by Natalie Angier, and it talks about subatomic particles like protons, neutrons and electrons in ...
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2answers
389 views

Change in intensity of electric field with constant velocity

Consider a +Q charged particle is travelling towards another test charge +Q. Now what would be the difference in electric field experienced by the test charge(avoid the gradual decrease in distance ...
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1answer
140 views

Charging using a CRT TV set

I was doing an experiment with my CRT TV where I put aluminum foil on the screen wire it to a can and open the TV and a ring between 2 can will swing if I ground the other can. ...
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0answers
175 views

Is the Hawking radiation of a charged black hole thermal?

Suppose you have a Schwarzschild black hole of mass $M$ and angular parameter $a = 0$ (no rotation). Question: is it possible to throw a charge $Q$ at a faster rate than it will be re-radiated? Will ...
3
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1answer
250 views

Semiconductor problem: how much Boron is required to establish a certain amount of charge carrier density

The problem description is as follows: Boron is used to dope 1 kg of germanium (Ge). How much boron (B) is required to establish a charge carrier density of 3.091 x 10^17 / cm^3. One mole of ...
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1answer
314 views

Charge on capacitor plates in series combination?

Suppose 2 capacitors are connected in series, the plates connected to the battery terminals receive charges $+q$ and $-q$, and the isolated plates in the combination receive equal and opposite charges ...
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1answer
206 views

About voltage and charge of van de graff generator

I have read that in case of Van de graff generator $V=kQ/r$ where $r$ is radius of the sphere. If that's the case, does the same voltage results in bigger charges in bigger radii?
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2answers
417 views

Conservation of Charge and Method of Images

Consider the typical problem, "You have a conducting sphere of charge $Q$ and a point charge q a certain distance away, what is the force on the point charge?". The solution is a simple application of ...
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4answers
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Delta Dirac Charge Density question

I have to write an expression for the charge density $\rho(\vec{r})$ of a point charge $q$ at $\vec{r}^{\prime}$, ensuring that the volume integral equals $q$. The only place any charge exists is at ...
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1answer
268 views

Will I recieve a shock if I charged a capacitor then i touch the 2 poles in same time?

What happens if I charged a capacitor then i touch the 2 poles in same time?
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1answer
73 views

Can we transfer the charge on a plate of a capacitor elsewhere?

I know it is hard , but can we transfer the charge on a capacitor plate elsewhere?
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1answer
68 views

Charge of an electrolytic capacitors

I can't understand the electrolytic capacitors, when a capacitor has a capacitance of 100 microfarads, does that mean that when it is charged with 100 volts will the charge of the plate be 0.01 ...
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1answer
285 views

Can high charges (like $1\times 10^{-3}$ coulomb) be acheived?

How can we charge a metal electrode with large charges ? When i saw a video about measuring a charge using a visiostat on a balloon , the charge was 0.6 nano-coulomb. Is the charge of 1 coulomb ...
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2answers
6k views

Why is electric field zero inside a hollow metal sphere ?

The figure below shows a hollow metal sphere with a positive point charge $Q$ sitting outside it. What is the electric field at the center of sphere ? The answer is zero (look at here at the beginning ...
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2answers
713 views

Find the quantity of charge - given potential function

A potential function is given by $V(r)=\frac{Ae^{-\lambda r}}{r}$ Find charge density and hence charge. I first took the gradient of potential to get $\vec{E}(r)=\frac{Ae^{-\lambda ...
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2answers
627 views

why dosen't a charged particle radiate energy in circular motion in a uniform magnetic field?

I have studied in my Physics course that one of the drawbacks of Rutherford's atomic model was that when an electron will revolve around the nucleus, it is undergoing acceleration and so it should ...
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1answer
490 views

Simple quadrupole moment

I have a very simple problem: There is a charge $-q$ at $(0, 0, d)$ and $(0, 0, -d)$ as well a charge $2q$ at $(0, 0, 0)$. I have to calculate the quadrupole moment using spherical coordinates. I use ...
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4answers
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Gravity stronger than electromagnetic force in a black hole?

Well, the question has somewhat been answered before, but there's one part missing, which - I'd think - is in conflict with the physical laws. The earlier reply says that the gravitational pull even ...
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2answers
249 views

Effect of charges near a parallel plate capacitor

If I charged a parallel plate capacitor. And then, I insert a charged body near one of the plates. Will there be any interactions like attraction or repulsion? What if I disconnected the battery?
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5answers
774 views

Paradox with Gauss' law when space is uniformly charged everywhere

Consider that space is uniformly charged everywhere, i.e., filled with a uniform charge distribution, $\rho$, everywhere. By symmetry, the electric field is zero everywhere. (If I take any point in ...
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2answers
195 views

Energy in electric field

I'm having some trouble understanding a homework question and would appreciate some help. The question is as follows: Jenny charges a capacitor with the help of a battery. She then removes the ...
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3answers
362 views

Change in attraction of charged bodies

If I insert a piece of glass between two objects carrying different charges, would they still attract? If they attract, does the piece of glass affect the force of attraction and is there any formula ...
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2answers
499 views

Is it possible to charge photons

For example there are anti-particles to every particle we know, Similary in some sense, is there a possibility that we can charge photons..if not what are the reasons and has there been any attempt ...
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1answer
417 views

Excess charge on an insulator and conductor

So I was recently wondering what happens to the excess charge when it is placed on an insulator or conductor e.g. rubbing two objects together. I know in the conductor the electrons are free to move ...
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2answers
405 views

What's the deepest reason why QCD bound states have integer charge?

What's the deepest reason why QCD bound states have integer electric charge, i.e. equal to an integer times the electron charge? Given that the quarks have the fractional electric charges they do, ...
3
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1answer
180 views

Why are electric charges allowed to be so light but magnetic monopoles have to be so heavy?

My question is in two parts. What is the origin of the electric field from an electric charge and why electron can have so small mass? While on the other hand for a magnetic monopole to create a ...
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2answers
136 views

Showing that electron and positrons have the same absolute charge

In Zee's quantum field theory in a nutshell, 2nd edition, pg 551 he has the charge of a Dirac field written as $Q=\int {d^3p \over (2\pi)^3(E_p/m)} \sum_s ...
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1answer
153 views

Charge and the Dirac field

In Zee's quantum field theory in a nutshell, 2nd edition, pg 550 he has $Q=\int {d^3p \over (2\pi)^3(E_p/m)} \sum_s \{b^\dagger(p,s)b(p,s)-d^\dagger(p,s)d(p,s)\}$ showing clearly that $b$ ...
4
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2answers
351 views

Sum total distance of electrons on a spherical surface

What is the sum total distance between every possible pair of point charges when there are n point charges on a spherical surface? All point charges can only and are located on the infinitesimal ...
3
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1answer
665 views

Does electric charge affect space time fabric?

I am confused with this question. Does electric charge affect the space time fabric? If so, why? Also if electric charge does not affect the space time fabric, how can we interpret the origin of the ...
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0answers
223 views

What makes *electric* charge special (wrt. CPT theorem)?

I'm wondering why the 'C' in CPT - charge conjugation - refers specifically to electric charge. Of course you could say that C is just defined as $e^+ \leftrightarrow e^-$... but there has to be ...
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3answers
337 views

Negative Mass and gravitation

Since Newtonian gravity is analogous to electrostatics shouldn't there be something called negative mass? Also, a moving charge generates electric field, but why doesn't a moving mass generate some ...