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

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14 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
50 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
39 views

Can a lightning strike cause your car to not run? [migrated]

If lightning strikes a tree in your yard and your car is close by, can this cause your car to not work properly? I had an employee call in stating that lightning struck a tree beside their mobile ...
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1answer
24 views

Flow of charge through metal wire [on hold]

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 ...
0
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0answers
25 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 ...
3
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1answer
1k views

What is the electric charge of the Sun and its corona?

What is the net electric charge (in magnitude and sign) of the Sun and its corona?
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1answer
22 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
35 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 ...
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1answer
45 views
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3answers
4k views

How is bound charge and free charge possible?

I am studying Introduction to Electrodynamics by Griffiths and I came along a concept I cannot seem to understand properly. The concept of free charge AND bound charge. I do not understand how we can ...
2
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1answer
306 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 ...
-4
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0answers
26 views

Where is the net electric field 0? [on hold]

A positive charge +3Q is separated by a distance, d, from a negative charge -Q. What is the closest distance in which the net electric field is zero.
6
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1answer
524 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 ...
14
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7answers
1k 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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2answers
155 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 ...
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4answers
191 views

Voltage - Energy drop

I'm having a hard time understanding the nature of voltage and am hoping you guys can help. The main issue is the concept of the voltage drop. Take the following circuits : In regard to the first, ...
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0answers
17 views
1
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1answer
30 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. ...
0
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1answer
24 views

Motion of an electric charge within an electric field with two electric charges

Assume that air resistance and gravity are negligible and the only significant force acting in the scenario is the electric force. There are two electric charges, both with an equal and positive ...
0
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0answers
28 views

Electric potential inside a conductor inside another conductor [closed]

Suppose there is a neutral hollow conductor body $B_2$ and there is another hollow conductor $B_1$ inside $B_2$ . Let there be a charge $q$ on $B_1$ . Let the potential inside $B_2$ but outside $B_1$ ...
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1answer
266 views

Force and Energy of interaction of conducting sphere and point charge

A completely isolated neutral conducting sphere of radius $R$ is kept such that its center is at a distance of $r\left(>R\right)$ from a point charge $+Q$. How can I find the force of ...
1
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1answer
70 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 ...
2
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1answer
32 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 ...
4
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3answers
60 views

Spherical Shell with Electric Field Zero Everywhere Inside It

If an isolated, charged spherical shell has a uniform charge distribution, the electric field everywhere inside it is 0, by Gauss' Law. Is the converse true? That is, given an isolated, charged ...
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
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0answers
23 views

How is corona discharge different from regular electricity ? [closed]

Since corona discharge is a electrical discharge is it any different from regular electrcity in terms of its ability to travel through wires, create magnetic fields , etc.
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2answers
42 views

Do Weyl fermions carry electric charge?

Do Weyl fermions carry ordinary electric charge? That is, do they interact with, for instance, electrons or photons?
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1answer
36 views

Surface density charge, divergence of the electric field and gauss law

It´s known that the divergence of the electric field at a certain point is given by this formula: $$\nabla \cdot E=\dfrac{\rho (r)}{\epsilon_{0}}$$ Being $\rho (r)$ the volume charge density at that ...
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1answer
52 views

Why are electrons negetively charged? [duplicate]

Why have we assigned a negative charge to electrons (and positive for protons)? I feel it would be easier if electrons were positive (thereby, protons negative)- electrons would flow in the direction ...
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0answers
13 views

Laws of electrolysis and quantisation of charge relation [migrated]

The quantisation of charge was first suggested by the experimental laws of electrolysis discovered by Faraday I think about it a lot but could not find any relation, as the number of electrons ...
4
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1answer
80 views

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

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, what ...
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0answers
25 views

What exactly is Breakdown Voltage of Air?

Most of the online sources say that the breakdown voltage of air is 30kV/cm. I've made a Cockcroft Walton multiplier and I can see the air breaking in between 17-18kV/cm. Only in a discussion at one ...
0
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0answers
60 views

Why is there no negative mass? [duplicate]

We know that the entire matter has a property called mass. Charge is also a property of matter. If negative charge can exist, why don't negative mass exist? Also, like charges repel each other. Then ...
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1answer
40 views

What are all charge-like quantum numbers?

What are all charge-like quantum numbers? In particle physics there are often things (like charge conjugation) that apply to all charge like quantum numbers. Everytime I read something about ...
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2answers
609 views

How to find the distribution of charge on two spheres connected by a conducting wire?

A solid metal sphere of radius $R$ has charge $+2Q$. A hollow spherical shell of radius $3R$, concentric with the first sphere, has net charge $-Q$. What would be the final distribution of the charge ...
9
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1answer
243 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 ...
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1answer
202 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
36 views

Why is it said that electric current always flow from higher potential to lower potential?

Why is it said that electric current always flow from higher potential to lower potential? It is said that current flows from positive terminal to negative terminal, but it is actually the negative ...
0
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0answers
11 views

Potential energy of a shell & point system

Consider the system of a point particle with charge $q$ and a spherical shell with uniform charge $Q$ and radius $R$ whose center is a distance $r > R$ away from the point particle. I'm trying to ...
3
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2answers
12k 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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0answers
9 views

Charge distribution parametres

I'm reading an article regarding charge distribution parametres in muonic atoms ad I'm stuck in the very first pages. In particular, I don't understand, given a 2-parametre Fermi charge distribution ...
3
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2answers
137 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 ...
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2answers
248 views

Close or open circuit?

A electric source provides a non electrostatic influence on the charges inside the source which pushes the positive charges from the negative terminal to the positive one. Does this happen when the ...
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1answer
43 views

Gauss's law, electrical flux density [closed]

Q. Given a 60-μC point charge located at origin, find the total electrical flux passing through the plane z = 26 cm. I can understand what the question means, but I can't do anything. Is it using ...
0
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0answers
20 views

Choosing between a parallel-plate and spherical capacitor model

This problem is solved in the solutions manual by making reference to equations for the parallel-plate capacitor. I have some basic understanding of why this is the case (the local curvature is small ...
1
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1answer
39 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 ...
2
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3answers
439 views

If we connect a block of p-type semiconductor only to a positive terminal, will it become positively charged?

Connect the positive terminal of a battery to a piece of p-doped semiconductor, say, silicon doped with boron. Will the terminal pull electrons out of the doped silicon, or equivalently, inject holes ...
3
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1answer
8k views

Charge inside conductor

I know that the $E$ field inside a conductor is zero. What happens if I put a source of charge inside the conductor? Say the conductor was spherical centered on the origin and there exists a charge ...
0
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2answers
14 views

Electric potential energy of a charge

Potential energy is the work done by the particle against a conservative force. Isn't it? when a charge is fixed on a free space and then when we bring another charge from infinity to a distance r ...
0
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0answers
42 views

Charged conducting wire ring and Greens function

ρ(r) = q 2πa2 δ(r − a)δ(cos θ). If this is my charge distribution on a conducting wire ring. radius=a. I am attempting to show my electrostatic potential as an integral along the z-axis I started by ...