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Questions tagged [charge]

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

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3answers
7k 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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3answers
926 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
446 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. http://scitoys.com/...
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1answer
972 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
708 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
1k 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
974 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
12k views

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
965 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
113 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
90 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
1k 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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3answers
34k 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
4k 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 r}}{r}[\lambda+\...
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3answers
2k 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
3k 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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5answers
4k views

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
772 views

Effect of charges near a parallel plate capacitor

If I charge a parallel plate capacitor and I insert a charged body near one of the plates will there be any interactions like attraction or repulsion? What if I disconnect the battery?
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4answers
14k views

Distribution of charge on a hollow metal sphere

A hollow metal sphere is electrically neutral (no excess charge). A small amount of negative charge is suddenly placed at one point P on this metal sphere. If we check on this excess negative ...
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7answers
3k 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
641 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
937 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
5k 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
2k 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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3answers
1k 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, ...
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1answer
278 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
159 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 \{b^\dagger(p,s)b(p,s)-d^\dagger(p,s)d(p,...
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1answer
331 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 $b$ ...
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2answers
832 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 ...
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1answer
3k 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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1answer
522 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
913 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 ...
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3answers
4k views

What is the maximum surface charge density of aluminum?

I understand that the maximum free charge carrier density for aluminum has been measured using the Hall effect (in the case of electric current). However, I'm not clear how to determine the maximum ...
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0answers
877 views

Why is it that protons and electrons have exactly the same but opposite charge? [duplicate]

Possible Duplicate: Why do electron and proton have the same but opposite electric charge? Doesn't it seem very curious that one is an elementary particle and the other a subatomic particle yet ...
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3answers
528 views

Charge Analog of the Higgs Boson?

Since mass can be given to particles via the interaction with the Higgs Field could there be a "Charger Field" that supplies particles with charge? Possibly this would require two different "charger ...
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3answers
2k views

Parallel-plate capacitor

I'm trying to grasp parallel-plate capacitors in a class of electromagnetic field theory. My book leaves out a lot and I couldn't figure it out from what I found on Google. The book's procedure is to ...
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2answers
3k views

Why do we need Higgs field to re-explain mass, but not charge?

We already had definition of mass based on gravitational interactions since before Higgs. It's similar to charge which is defined based on electromagnetic interactions of particles. Why did Higgs ...
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2answers
469 views

Force due to combination of free space and dielectric

I will make a generalized form of my question. There are two point charges $q$, $x$ distance apart. And there is a dielectric slab of thickness $t$ and of dielectric constant $K$. Should the force ...
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1answer
3k views

Linear charge density, surface charge density and volume charge density

What is the difference among: linear charge density, surface charge density, and volume charge density?
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3answers
2k views

Dirac's quantization rule

I first recall Dirac's quantization rule, derived under the hypothesis that there would exit somewhere a magnetic charge: $\frac{gq}{4\pi} = \frac{n\hbar}{2} $ with $n$ a natural number. I am ...
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7answers
7k views

Does a charged particle accelerating in a gravitational field radiate?

A charged particle undergoing an acceleration radiates photons. Let's consider a charge in a freely falling frame of reference. In such a frame, the local gravitational field is necessarily zero, ...
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4answers
21k views

Why do electron and proton have the same but opposite electric charge?

What is the explanation between equality of proton and electron charges (up to a sign)? This is connected to the gauge invariance and renormalization of charge is connected to the renormalization of ...
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1answer
2k views

What is “charge discreteness”?

I assume it is some kind of quantity. Google only made things more confusing. I get that it has something to do with circuits. I also get what a discrete charge is. In fact, I thought charges were,...
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3answers
10k views

How much electric charge do electromagnetic waves carry?

Since electromagnetic waves have both electric and magnetic field components, which oscillate in phase perpendicular to each other and perpendicular to the direction of energy propagation. How much is ...
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2answers
140 views

Two charged black holes in equilibrium

Consider a pair of (possibly rotating) charged black holes with masses m1, m2 and like charges q1, q2. It seems that under certain conditions gravitational attraction should exactly cancel ...
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11answers
41k views

Why is the charge naming convention wrong?

I recently came to know about the Conventional Current vs. Electron Flow issue. Doing some search I found that the reason for this is that Benjamin Franklin made a mistake when naming positive and ...
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3answers
21k views

Do moving charged particles have both magnetic and electric fields?

Consider a charged particle (electron or proton) at rest. It is surrounded by its own electric field. Now consider an electron moving with certain velocity. Is there still an electric field around it?...
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3answers
659 views

Charging a black hole?

What would happen if we have a black hole and we start shooting at it a single electron at a time, and go on doing it forever? Would the electrons start to bounce off eventually?
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8answers
25k views

Why do we test electric fields with positive charges and not negative ones?

Is there any difference between using a positive versus a negative charge to test an electric field?
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2answers
3k views

What role does electrical charge play in black holes?

Not having studied General Relativity, I have sometimes been puzzled by references to the behaviour for "classic" black holes — as they are popularly portrayed — as being true for black ...