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

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2k 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 ...
0
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0answers
6 views

Does the charge of a black hole affect its space-time geometry?

Does a black-hole of a given mass and angular momentum have the same space-time geometry regardless of its charge? I'm pretty sure that an electric field can accelerate a charged particle but doesn't ...
1
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1answer
15 views

Charge of electron in AC/DC circuit

If electrons in a DC circuit going through a metal wire carry only negative charge from negative to positive, then in a AC circuit through a wire does a electron carry both a negative charge and ...
0
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1answer
34 views

Majorana fermion [on hold]

I know that in condensed matter physics Majorana fermion is neutral and one fermion can be split into two Majorana fermions and vise versa. My question is charge. Two neutral particles can merge into ...
18
votes
4answers
3k views

Why don't loop currents produce light?

If a charge travels in a circle it must accelerate, thereby producing EM. However, a wire in a circular loop is analogous to many charges moving in a circle. So, why don't circular currents produce ...
2
votes
2answers
23 views

Charge distribution on a conductor surface

I understand that if a conductor was charged with a charge of say 1 coulomb, the charge would spread uniformly over it's entire surface to neutralize any difference in potential. However, and though ...
3
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1answer
53 views

Removing an electron from a conductor

I'm trying to understand how to think of and visualize a conductor where charge is added. As I understand, conductor are defined as materials (where the nucleus is stationary) that permit electrons ...
62
votes
6answers
7k views

If like charges repel, why doesn't a charge break itself apart?

How can it be that, if like charges repel, they don't repel themselves? In other words, why don't charges break apart? About the possible duplicate: I want to know about charges in general, not ...
2
votes
2answers
249 views

What is the difference between emu and esu?

Ok...so this is the statement given in my book: a) In C.G.S System the unit of charge is electrostatic unit of charge (E.S.U). It is also called Stat Coulomb (StatC). b) In C.G.S system, the unit ...
12
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1answer
270 views

How can I find the position of an image charge when the boundary is parabolic or hyperbolic?

If the position of some charge $Q$ is known, the boundary condition is $u=0$ on some parabolic surface, and we know the image charge has its electric volume of $Q'$, then how can I determine the ...
8
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1answer
291 views

Why doesn't an electron's charge rip the electron apart? [duplicate]

Like charges repel. What keeps an electron's charge from repelling itself? This problem would come up if an electron was divisible and its parts had fractional charge. A related question is, ...
0
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1answer
175 views

How does a minority carrier diffuse?

I have gone through a lot of questions but none of them ask how do the minority carriers approach the depletion layer in the first place. When a p-n junction is formed, negative space charge ...
3
votes
2answers
177 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 ...
6
votes
1answer
70 views

Charge structure of the neutron

David Griffiths’ book on elementary particles says that the neutron is positive at the center and edges, negative in between. (Introduction to Elementary Particles, Wiley, 1987, p. 21). But Wikipedia ...
-2
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0answers
23 views

Charging Copper ball bearing

I want to conduct an experiment to observe the trajectory of charged particles in applied magnetic and electric field. Thus, I want to charge a copper bead/ball bearing. How can I electrically charge ...
3
votes
0answers
81 views

Question on the Derivation of Lorentz Invariance of Electric Charge

On Zwiebach's "A First Course in String Theory" textbook, there is a problem 8.2 that derives the invariance of electric charge given a few assumptions: 1. Conservation of Maxwell 4-current $j = (c\...
3
votes
1answer
97 views

Find magnetic field of parabaloid-spiral particle path

Given the components of the particle's path (tcos(at), tsin(at), R(x^2 + y^2)), where a and R are constants, how can I find the magnetic force causing this? I would like to understand if this can be ...
3
votes
3answers
13k views

Electric field of a negative charge

How was it discovered that the electric field of a negative charge points towards the charge itself? Is it true? (Courtesy of wikipedia)
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2answers
177 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 ...
14
votes
3answers
945 views

How did physicists know that only negative charges move?

I have phrased similarly another question about how physicists knew that two charges exist, positive and negative. The purpose of the question is not necessarily to educate me historically. It's just ...
0
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0answers
13 views

Current through a chargedwire

When current is passed through a conductor which is negatively charged ( has excess electrons), what will be the effect on the current due to this charge? In the case of a hot filament used for ...
0
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1answer
19 views

Connected and disconnected conductors spheres

I have an exercise in which I have the following situation: there are two conductors spheres (far apart) both of a given radius (R1, R2=2R1). The lesser sphere has a positive charge q and the other ...
0
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0answers
28 views

Effective mass vs. effective charge

In a semiconductor the effective mass multiplying the drift velocity is the result of the scattering of electrons off the ions in the crystal. I know that at least in the lowest order approximation ...
0
votes
1answer
47 views

Working out a specific charge of an atom?

I know how this formula work if the mass of the nucleus and the charge of the nucleus is given, however I do not understand how they get them as I have two books which do it differently. So the ...
0
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1answer
35 views

Kaufmann's experiment 1902

Kaufmann's experiments (1902): http://en.wikipedia.org/wiki/Kaufmann%E2%80%93Bucherer%E2%80%93Neumann_experiments#Historical_context About charge to electromagnetic-mass ratio. Fig 2 has a plot of ...
2
votes
1answer
121 views

Electric field in a hollow object

I am currently visiting a course about electrodynamics. In my last lecture it was said that if a hollow sphere is inside of a bigger sphere, but only in the bigger sphere there are spherically ...
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2answers
65 views

Why does there have to be an electric field if there is potential difference?

I read in a few books that there is always an electric field if there is an electric potential. I went through this but the question on this page only states that there is an electric field and it is ...
36
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5answers
5k views

How did physicists know that there are two kind of charges?

Problems The question I am about to make is either too stupid or hasn't bothered anyone because its obvious because I can't really find the answer anywhere. I am currently studying electricity and ...
0
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1answer
25 views

Measurement of electrostatic induction

How is it with the electrostatic induction measurement? Everywhere you can read about the effect of electrostatic induction but I still can't found any detailed explanations or quantitative ...
1
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2answers
166 views

Does charge of a metal charged by induction determine by which ends of the metal is grounded to?

Does charge of a metal charged by induction determine by which part of the metal is ground to? I draw a diagram to make it simple to understand: Right diagram: When ground is touched with the ...
2
votes
1answer
310 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 ...
-2
votes
1answer
28 views

Why does the metal ball have no appreciable charge?

here is the question: A hollow conductor is positively charged. A small uncharged metal ball is lowered by a silk thread through a small opening in the top of the conductor and allowed to touch its ...
11
votes
3answers
2k views

Will a giant ball of protons form a black hole?

Suppose you have enough energy and resources to put together (in a momentarily static configuration in which they are all at rest at the same time) as many protons as you want to form a "proton star". ...
4
votes
4answers
203 views

Electric field dependence on distance

How can it be proved that for a point charge, $E$ is proportional to $$1/r^2$$ using the concept of Electric field lines (or lines of force)? I tried to show that if field lines are close, then ...
1
vote
2answers
74 views

Discharging a capacitor

Suppose I have a charged capacitor, meaning there's a voltage (electric potential difference), say, $2V$, between its two plates. We don't know the electirc potential of the individual plates, right? ...
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votes
1answer
26 views

Electric field of a line charge, along itself

look at the pic : What is the electric field in along the line of charge with charge density $\lambda$ and length $L$. Is the electric field zero along the line without any difference in height?
21
votes
8answers
5k views

How can a battery charge up another battery to a higher percentage?

Say I have my phone on 5% and a large battery pack on 35% and I charge the phone. By the end the phone is on 100% and the pack is on 12%. How can the battery pack charge the phone up to a higher ...
1
vote
4answers
134 views

Electron losing its charge

If the electron is said to be a charge carrier, then could it lose its charge ? It wouldn't remain an electron ofcourse , because charge is one of its important properties . But am talking about the ...
1
vote
0answers
31 views

Regarding the zero internal electric field in a conductor (electrostatic case)

Let's say we have a homogenous electric field in the $z$-direction. For computational simplicity let's say we have a thin sheet of metal covering entire the $x$-$y$ plane. The answer here is straight ...
1
vote
2answers
339 views

Why do charge on an object remains unaffected by the motion of the object?

Unlike mass, the charge on an object is said to be unaffected by the motion of the object. This statement in my text book, is not yet understood by me. I don't know theory of relativity. On ...
0
votes
2answers
74 views

Why is the magnetic force not (never) in the opposite direction

In this question I'm talking about the left-handed orientation for the direction of the $x$, $y$ and $z$-axis. This is the coordinate system at the left of the picture below. I learnt that when you ...
0
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1answer
76 views

Point charge inside a electrically neutral cavity in conductor placed eccentrically, and effect of external electric field if switched on

bear with me, but i would like a definite answer, now, starting off the external charge density on the outer surface of sphere WILL be uniform by unique solution of Laplace equation and letting the ...
4
votes
1answer
80 views

Electric field due to a charged irregularly shaped balloon

There is a question in my textbook that says: A rubber balloon is given a charge $Q$ distributed uniformly over its surface. Is the field inside the balloon zero everywhere if the balloon does not ...
2
votes
2answers
472 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 ...
0
votes
0answers
61 views

Electron spinning speed and “matter” it is made from

I wonder how electron may have spin if its model has no space occupied solely by the electron. Is it possible to estimate this rotation speed knowing its mass, charge and magnetic field emerged? If ...
2
votes
1answer
213 views

Opacity/transparency of conductive meshes to charged particles (electrons/ions)

When using a conductive (metal) mesh, effectively a metallic woven fabric, in vacuum applications as a "grid" for charged particle optics, how does one calculate (or at least estimate) the opacity or ...
3
votes
1answer
125 views

How can black holes have electric charge and spin? [duplicate]

If the star's mass supposedly collapses into a single point, and it ends up having "said" zero volume, then how can people say that the hole has a specific spin or that it can have an angular momentum?...
4
votes
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 ...
5
votes
3answers
374 views

How close can two extremal black holes with the same charge can get?

Here's a puzzle I have been pondering over. If we have two extremal black holes with the same charge, the electrostatic repulsion between them ought to cancel the gravitational attraction between ...
8
votes
2answers
88 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 ...