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

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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 ...
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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". ...
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1answer
30 views

main cause of self charging of unshorted capacitors?

In the lab, we keep all of the high voltage capacitors shorted when not in use, and rightfully so. They tend to spontaneously charge when left for some time and become extremely dangerous. while the ...
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0answers
25 views

Three point charges are places on the x - axis [on hold]

Three point charges are placed on the x-axis. A charge of $+2\mu C$ is placed at the origin, $-2\mu C$ to the right at x = 50 cm, and $+4.0 \mu C$ at the 100 cm mark. What are the magnitude and ...
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1answer
12 views

How does the ion mobility influence the elctrical fiels?

So I have a system of three electrodes, anode, cathode and reference electrode. When I apply a negative current and then register somehow the activity of the sodium chloride solution. Then I apply a ...
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0answers
56 views

Do physicists find the fractional charge of quarks a problem? [closed]

Just seems to jar with the unitary values we have assigned arbitrarily of course when initial sub atomic particles were discovered. Seems that all the maths works but when you can have a 2/3 charge ...
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1answer
32 views

Does the charge leakage of capacitors lead to photon emission?

Capacitors will leak charge over time. This charge is basically electrical current leaking through insulating layer of the capacitor. I am wondering, if there is some emission of photons as there is ...
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3answers
1k views

How many kinds of “weak charges” exist?

For electricity, we have one charge, for the strong force three. How many are there connected to the weak force? Three, because of the W- and Z-particles?
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2answers
29 views

Surface charge outside conductor

If I have a hollow conductor of arbitrary shape, and have a charge placed inside is cavity, then is there anything I can say for sure about the charge distribution on the outer surface? I know that ...
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0answers
23 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 ...
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3answers
107 views

Energy of an accelerated charge?

Thought experiment: Let's take a positively charged particle and place it in a vacuum with no electric field. It just sits there. Now, we instantaneously introduce an electric field. The moment ...
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3answers
21 views

Difference in directions of charge and current.?

I just dont understand that why does charge flow in a different direction as that if current when current is the rate of flow of charge.
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1answer
49 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 ...
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1answer
50 views

Are pure Dirac fermions (electrons, quarks, …) allowed to have effective Majorana mass?

Charged particles such as electrons and quarks are not allowed to have a hard Majorana mass (see here). With 'hard' I mean an explicit mass term in the Lagrangian which would break the corresponding ...
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0answers
20 views

Can a Van de Graaff Generator be used to put plasma at high potential?

Lets say hypothetically, we use a sphere of plasma (ofcourse lab-plasma, stabilized somehow) instead of a sphere of metal in a van de graaff generator. Now can we use it to put a large amount of ...
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0answers
21 views

Can additional charge be put on plasma?

We all know that plasma is electrically conductive. My question is that is it possible to somehow place more charge on it (lets say like a capacitor) such that it produces its own electric field ...
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2answers
36 views

Determination of the electric field of charged object using Gauss's law

when we determine the electric field of a charged rod of infinite length,we consider a circular cylinder to be the gaussian surface for convenience.In the case of a charged sheet we choose the ...
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1answer
34 views

How to Explain the the following situation?

I have thought a simple thing: consider a system of a planet and its natural satellite revolving around it in a perfectly circular orbit(assumed) and this is happening in an isolated space in some ...
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1answer
71 views

Does changing a closed surface in the manner outlined contradict Gauss' Law?

As I understand it, Gauss' Law states that the electric flux on any arbitrary closed surface is equivalent to the sum of all charges enclosed within the surface times a constant. Mathematically, this ...
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1answer
18 views

Different charges of plates of parallel plate capacitor

Suppose the plates of a parallel plate capacitor have charges +2Q and -Q initially. Then if they are connected with a battery of emf V what will be the charge distribution on the plates of capacitor? ...
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0answers
16 views

How can I know the induced charge density in a dielectric?

There's an infinite conduciting plane lying over the XY plane, conected to a battery that keeps it at a constant potential $\phi_0$. At a distance $D$ from the plane there is a point charge $q$ that ...
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1answer
40 views

Is there a reason why every meson and baryon has an integer electric charge? [duplicate]

Is there a reason why every meson and baryon has an integer electric charge? For example, why is there no meson existing of two up quarks, giving a charge of $\frac43$?
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0answers
26 views

AP Physics 1/2- Electrostatics Capacitor [closed]

I recently took a physics exam over Electrostatics Capacitor and was unsure about a couple of questions. the test was free response and I had to explain. Please tell me if my answer and reasoning ...
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2answers
65 views

Two Black Holes held stationary by EM forces

If two black holes with large enough mass (so that the tidal forces are minimal and the intersection is large) that are held apart by like charges (saddle point stability). Imagine the black holes in ...
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1answer
24 views

Mechanism by which a capacitor is charged, using surface charges

I want to gain a deeper understanding as to how a capacitor actually gets charged. Consider a situation in which an uncharged parallel plate capacitor is connected to a battery using two wires. I ...
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2answers
45 views

Zero electric field in empty region of hollow conductor

A hollow conducting shell having a net charge of +Q has a point charge -Q placed at its centre. From the diagram, it looks like Suppose the radius of the inner shell from the origin is a and the ...
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0answers
54 views

Does charge injection from electrodes increases the total charge in a (semi)conductive channel?

When a (semi)conductor is connected to a voltage bias, a charge is injected by the electrodes. When steady state is reached (constant current flow), does the total charge of the (semi)conductor differ ...
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1answer
29 views

Is the $C$ rating of a battery a measure of Capicitance or Charge?

I have become confused as to the meaning of what a C rating of a battery means. My understanding is that because a C rating is measured in milli-ampere hours the units should cancel to be a unit of ...
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0answers
41 views

Feynman graph, proportional charge of a vertex

It is defined that the contribution of a vertex in a Feynman Graph towards the probability amplitude $ M_{fi} $ is proportional to a charge $Q_f$. Yet I seem to cannot find any precise explanation how ...
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3answers
83 views

How do particles get their charge?

How does an electron get its charge? And how can it maintain that charge for very long (infinite) periods of time? And how come a neutron has no charge since and a proton does? They are both made of ...
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1answer
53 views

When two like charges are placed at a large distance from each other, do they attract each other? [closed]

So my friend and I were arguing about this. He insists that if two like charges are placed at a large distance from each other, they attract each other. I find this nonsense. This clearly violates ...
3
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1answer
66 views

Why is it easier to remove stains with water?

And I don't mean stain removers, but literally tap water. See here's the thing, you can't remove a stain without some sort of friction, and water reduces friction. Yet if I say, spill some coffee and ...
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1answer
26 views

Magnitude of charge on each plate of a parallel capacitor? Why should I multiply by two?

Here's the full question: A parallel-plate capacitor has a plate area of $0.2\ \mathrm m^2$ and a plate separation of $0.1\ \mathrm{mm}$. To obtain an electric field of $2.0\ 10^6\ \mathrm{V/m}$ ...
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1answer
31 views

What does potential mean in capacitor?

Technically potential means work done to move a unit positive charge from one point to another against electrical field but What does potential mean in a capacitor?
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3answers
98 views

Relationship between electrons (leptons) and quarks

I assert the following is true: Either: electrons are made up of (two) quarks Or: Quarks are made up of some kind of smaller particles, which also make up electrons. I think this must be the case ...
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4answers
109 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 ...
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0answers
21 views

Reversibility of uniqueness theorem

If we use uniqueness theorem then we know that if the boundary conditions and the charge distribution is same in 2 setups in a certain region then the electric field and potential in that region in ...
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1answer
43 views

Flow of charge through metal wire [closed]

It is the flow of charge that matters -- electrical current is defined as the flow of charge. " -person W [...] if the flow of charge is all that matters; and electrons with their charge attached ...
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1answer
79 views

Why are there e.m. vacuüm fluctuations?

According to the rules of qft there are virtual photons in the vacuüm. But how can this be if for the production of photons you need an electric charge?
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0answers
34 views

Expressing charge density in terms of spherical multipoles

How to express the charge density in terms of the full set of the spherical multipole moments? That is, how to invert the relationship $$ Q_{lm}=\frac{4\pi}{2l+1}\int Y_{lm}^*(\theta,\varphi)r^l\rho(\...
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1answer
25 views

Is there a charge difference between ground and our head?

I commented on a question on Skeptics.SE that it would be an interesting question whether there is a charge difference between ground and our head. The question is not very relevant, but here it is ...
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3answers
40 views

Understanding Capacitors [duplicate]

I cannot understand how capacitors work. Electric field is supposedly uniform between the parallel plates of a capacitor. But how? Since $E=\frac{kq}{d^2}$, shouldn't the electric field approach ...
14
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8answers
2k views

Why is capacitance defined as charge divided by voltage?

I understand that capacitance is the ability of a body to store an electrical charge and the formula is $C=\frac{Q}{V}$. What I don't understand, however, is why it is defined as coulomb per volt. Of ...
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0answers
19 views

What is the potential difference between the plates? field around the plates? charge is on each plate? [closed]

What is the potential difference between the plates? field around the plates? charge is on each plate?
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1answer
35 views

How do I determent the radius and the viscosity of air on an oil drop falling? (Millikan's Oil Drop Experiment)

I bought this article with the intentions of learning how to do the calculations in Millikan's oil drop experiment. http://iopscience.iop.org/article/10.1088/0143-0807/33/5/1227/meta;jsessionid=...
1
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1answer
93 views

Electric Flux is zero

When is the Electric Flux zero through a closed surface? I know that if number of field lines entering is equal to leaving then it is true. Which I think is always true for a closed surface. So can ...
0
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0answers
34 views

What is the definition of electrical charge? [duplicate]

In one simple sentence what is the definition of charge as I don't understand what role it has in a circuit. Thank you
2
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1answer
54 views

What is maximum energy we can extract from electric field?

I was reading Does Electric field has mass Energy; it gives energy density k stored around an electric charge as $ k = \dfrac{q^2}{r^4}$ in skeleton form without any constants. So, a definite amount ...