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

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330 views

What proved Conventional sense wrong?

What fact proved for the first time that the conventional sense of current was wrong? And when it did happen? As a corollary of this question, why do we say that electrons have negative charge? Is it ...
2
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0answers
80 views

In string-net condensation, what does the quantized charge means? [closed]

The electrical charge is quantized strictly for elementary particles. What kind constraints does this fact applied to string-net theory? For the this question, I want to understand why electrical ...
0
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1answer
55 views

Semiconductor intrinsic carrier concentration is given by ni=BT^(3/2)*exp(-E/2kT), how is this derived?

The glorious book Sedra/Smith Microelectronic Circuits states that for a semiconductor the intrinsic charge concentration is is given by: $$ n_i = BT^{3/2}e^{-E_g/2kT} $$ Where $n_i$ is the ...
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0answers
77 views

How the experimental charge $e=1.60217657 × 10^{-19} C$ has precisely this value?

The coupling constant that we measured in "arbitrarily" low energy is $e=1.60217657 × 10^{-19} C$. How this is presented in Renormalization Group flow in charge coupling space? Why the action of the ...
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2answers
77 views

Electrostatics Basic Question

Why ,if we increase the charge on a conductor its potential also increases? That is, Q directly proportional to V. Why ,if an insulated conductor is given some charge it acquires a certain ...
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1answer
32 views

What does “touching” mean in the context of charge by conduction in electrostatics?

So in our physics class today, we had a demonstration involving a charged rod and a neutral ball attached to a string (a physical pendulum). At first, when the rod was placed near the ball, the ball ...
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1answer
27 views

charge density is a constant or a scalar-value function of position?

Since it is "density", I suppose that such values as charge density of a volume region $\rho_v$, charge density of a line $\rho_L$, and charge density of a surface $\rho_S$ is a constant but I ...
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2answers
158 views

Can one proton attract two electrons?

Suppose that in an empty space there is only one proton. This proton would have created a field of positive charge which should attract possible negative electrons, so now we add two electrons on ...
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1answer
58 views

Repulsive force between same charged plates?

I understand that the attraction force between parallel plates of capacitor is the derivative of stored energy with respect to distance of the plates. But how could we find the repulsive force between ...
0
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1answer
64 views

Why does Ampère's force only linearly depend on the distance between the two wires?

When we encountered Ampère's force law our professor stated: In the formula of the magnetic force you don't find $r^2$ as in the gravitational and the electric one because while those directly ...
0
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1answer
35 views

2D room with electron-point-charges (stability)

Is there a fast way to find out stable #"point charges" & constellation for this kind of Simulation. The 2D repeating itselve in each direction till infinity, so i've a kind of symetrie here. ...
2
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1answer
89 views

Charge operator for Dirac spinor

In QED, the gauge transformation which acts upon a fermionic field $\psi$ is $$\psi'(x)= e^{i \alpha(x) Q}\psi(x)$$ where $Q$ is the charge operator. Most of the time it's just written as $$\psi'(x)= ...
2
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1answer
35 views

Is it possible for the phase of electric charge to change over large general relativistic distances?

Jackson provides examples of how magnetic charge and electric charge form together to create complex charge, \begin{align} \rho = \rho_e+i\rho_m \end{align} which gives rise to the complex faraday ...
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0answers
64 views

How to theoretically determine electric charges of $W^{\pm}$ bosons?

I just realised that I don't remember how to conclude theoretically that $W^{\pm}$ bosons have electric charges of $\pm 1$. After some searching I'm quite surprise that I couldn't find a satisfying ...
2
votes
1answer
89 views

What does it signify that electrostatic mass cannot exist without inertial mass?

From Coulomb's law and Newton's second law we can state that if there is electrostatic mass (charge) at any point of space then there has to exist inertial mass also at that point of space. Otherwise, ...
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0answers
46 views

Li-ion Battery charging

Why are constant current mode and constant voltage mode needed when charging Li-ion batteries? Why do we apply saturation charge even after the cell voltage reaches 4.2V? What exactly is 'I-sense' in ...
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0answers
24 views

Why is there no charge in a capacitor connected to one battery pole? [duplicate]

Here is a very simple drawing of a battery pole and a capacitor plate connected by a wire (exaggerated in thickness). The question is, why is the capacitor not being charged? But as you will see ...
0
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0answers
35 views

Do charges attractions cause time dilation? [duplicate]

I was pondering whether charges will cause time dilatation? Let me explain more, well we know that gravity causes time-dilatation because of gravitational acceleration which is equal to: $$a = ...
2
votes
1answer
126 views

Virtual Photon transmission speed of a Static Electric Field?

In the case of a non-accelerating point charge "A" of stable velocity, its static field is treated as though it is instantaneously present at a distance, i.e. a second point charge "B" will react to ...
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0answers
23 views

Dispersion of electrons in conductive medium

Say you have a 1'x 1'x 1' cube of conductive metal. If you placed an electrode on the center of one of the sides, and quickly turned it on and off, how would the electrons disperse? Both initially ...
3
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4answers
268 views

The electric field in wires in a circuit

I have a hard time really understanding the electric field in a complete curcuit. How is the electric field maintained throughout the wiring / the conductors from component to component? The charges ...
0
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1answer
128 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 ...
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1answer
7k views

Does a positive or negative charge attract a neutral object?

Three objects are brought close to each other, two at a time. When objects A and B are brought together, they attract. When objects B and C are brought together, they repel. From this, we conclude ...
2
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1answer
54 views

Relativistic Induced Magnetic Field in particle's frame

Suppose there is a constant magnetic field: $\vec{\mathbf{B}} = B \hat{z}$. A charged particle orbits that magnetic field perpendicular to the magnetic field, and induces a magnetic field in the ...
0
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0answers
69 views

Zero net force on grass seeds - is this a uniform field?

Grass seeds mixed in an insulating liquid have a dipole moment (and thus behave like a dipole) when two charged electrodes are stuck in. A well-known experiment. Those grass seeds are polarized and ...
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0answers
27 views

What are some most advanced theories explaining why same charge repel, opposite charge attract? [duplicate]

It is the holidays with a lot to think about. One of the thing that I couldn't get out of my mind was something I read in Stephen Hawking's "Brief History of Time". In it, he described the repelling ...
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1answer
121 views

Gauss' Law - Parallel plates [closed]

A parallel plate capacitor with dielectric (as above), together with its dimensions. Its plates are square. The capacitance is given by the usual formula, $C = \frac{\epsilon _0 \epsilon _r ...
6
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2answers
755 views

How do electrons get a charge?

Electrons belong to a group of elementary particles called leptons. There are charged and neutral leptons. And electron is the charged one. But how come it got charged? The negative or positive ...
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0answers
40 views

Can Van Allen Radiation belts act as a capacitor?

There are two Van Allen Belts at rougly 5000Km and 17000Km from the surface of the Earth each of them containing majority of one of the charges electrons and protons). Can these belts like a ...
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0answers
13 views

how to completely remove the charge from the glass bubble particles?

Do you have any idea on how to completely remove the charge from the glass bubble particles (25-32 micrometer diameter)? Thanks
0
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1answer
131 views

Electric field of a charged object

1-The Lorentz Force Law states that $F=q(E+vB)$. Therefore, let's say that we have a point charge with charge $q$. If we want to calculate the force exerted by a charge $q_1$ on another charge $q_2$ ...
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0answers
125 views

Why is electric charge the conserved quantity corresponding to global $U(1)$ symmetry? [duplicate]

An example of a symmetry transformation for certain Lagrangians (notably the canonical complex scalar field Lagrangian) is multiplication of the fields by a complex phase. When we multiply the fields ...
0
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1answer
80 views

Is there a field for which neutral particle and antiparticle, can be considered as positive and negative charge?

I apologize, but QFT is not my domain. What I ask is connected with the question Do the fields exist without charges? . By analogy with the electron and proton, that carry the electric charges of the ...
3
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2answers
168 views

Do the fields exist without electric charges? [closed]

I read in an old book on electrodynamics by Pauli that theoretically there does not exist any need of charges to be there. Fields can even exist without the charges but still independent fields ...
1
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1answer
235 views

Density of charge induced on a hollow sphere due to eccentric charge inside

Suppose we have a lone hollow metal sphere with net charge equal to $0$. If we were to put a point charge $Q$ inside of the sphere and move it, let's say, away from the sphere center at some distance ...
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1answer
38 views

How to induce charge in glass bubble particles ?

I am trying to induce charge ( + or - ) in the glass bubble particles ( manufacturer 3M 25-32 micrometer) . Can anyone tell me how to effectively charge them. I have tried placing these particles in a ...
0
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0answers
149 views

The force acting on a plate of a parallel capacitor

How can you prove (using high-school-knowledge) that the force which acts on one plate of a parallel capacitor is equal $F = \frac{E \cdot Q}{2}$ Where $E = \frac{U}{d}$ is the magnitude of the ...
2
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1answer
27 views

Fully Ionic Grapefruit

Imagine I take a small grapefruit (about 100 grams), and a magic wand, and use the magic wand to : Remove all the electrons from my grapefruit. Prevent said grapefruit from exploding into a thin ...
0
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1answer
72 views

How does An Electric Field Create a Dipole Moment of a Rydberg Atom?

I know that an Rydberg Atom will not usually have a Dipole Moment - as the positive nucleus are surrounded by a negative electron cloud, so there is no uneven charge distribution. However, I also ...
3
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1answer
77 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 ...
2
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0answers
36 views

Why does electrolysis require a base electrolyte instead of an acid electrolyte?

I am in the process of using electrolysis to remove rust from some old tools. This is the process where you submerge the rusted item in a bath along with a sacrificial piece of metal. You connect a ...
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2answers
82 views

How is charge expressed?

I am happy with the concept of electrons interacting with each other through the emission and absorption of photons, but what I don't understand is how the negative charge on an electron is expressed ...
2
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1answer
43 views

Disturbing a line of infinite alternating charges

Consider a line of infinite number of alternating charges. All are point charges having charge of same magnitude and are placed in a line. Neglect the effect of gravity here. Consider one of the ...
0
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0answers
22 views

Why do we assign an electric field vector to an EM wave when photons have zero charge? [duplicate]

In the standard model photons have no charge. So how can en EM wave be given a quantity of electric field to do work on electrons in say a RF antenna. What excites the electrons? I may have parts of ...
2
votes
3answers
367 views

How do two electrical charged particles know to repel or attract each other?

Now per QED, electrical charges interactions are effected by photons. Suppose you are one of the two charges. How do you know to attract or repel the other charge? In other words, how do you know if ...
0
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1answer
115 views

Is charge transfer from A to B positive or negative?

I see this term pop up a lot -- for instance "charge is transferred from atom A to atom B", but it's never specified whether they're talking about positive or negative charge. I know electrical ...
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0answers
126 views

Simplify QCD Lagrangian

How we can derive the electric charge of the field theory for each field? For example lets say that we have the u-quarks (3-colors) and electron that we know that has charge -e) free Lagrangian ...
2
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1answer
46 views

Charge density and space inversion

J. D. Jackson in his book Classical Electrodynamics on page 249 ff. discusses the behaviour of electromagnetic quantities under space inversion (parity operation) and time reversal. He remarks: ...
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2answers
86 views

Relation between electric field and dipole moment

I want to show the following equality $$\int_{\left|\vec{r}\right|<R}d^3r\vec{E}\left(\vec{r}\right)=-\frac{\vec{p}}{3\epsilon_0}$$ where $\vec{p}$ is the dipole moment of a charge distribution ...
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1answer
154 views

Charge distribution on a doughnut shaped conductor

In a spherical solid conductor the charge is always on the outer surface. Even if the sphere has a cavity, the surface of the inner cavity can not carry a charge due to Gauss's Law. What would be ...