Electrostatics is concerned with the electrical fields and scalar potentials of stationary electrical charges and charge distributions. Use this for questions about electromagnetic situations in which currents and magnetic fields are absent, otherwise use [tag:electromagnetism] and/or ...

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Nucleus validation

Inside the nucleus of an atom is the Coulomb's law valid? I mean that between proton, neutron and other elementary particles, i.e., meson etc. What will be the limit or validity of charges between ...
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20 views

Electric Fields in a Neutral Object

A neutral object has no net charge since its positive and negative charges cancel each other. However, I’m wondering how, in terms of fields, they do cancel each other. Since fields are vectors, won’t ...
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Do Anodes Emit Virtual Photons Representing Their Positive Electrostatic Potential

I understand the electrons in circuit travel down the path of least resistance, however are electrons attracted by the emission of virtual photons emitted by a source with relatively low electron ...
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The Electrostatic-Potential Variable of the Work Function Without the Presence of a Vacuum

In the Work Function Equation, the variable of the Electrostatic-Potential is described as the Electrostatic-Potential of a vacuum nearby the surface. However, how would this variable change if there ...
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When is work done on or by something?

An example, here what my textbook says: When charges are released In electric fields charges experience the force causing them to accelerate along electric field vectors. Positive charges ...
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1answer
39 views

Electric field between capacitors [on hold]

A parallel-plate capacitor consists of two parallel, conducting plates of area $A$, separated by a distance $d$. Each carries a charge of magnitude $Q$; positive on one, negative on the other. ...
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2answers
36 views

Is this diagram in my textbook not constructed to scale?

Or am I having an illusion. Clearly, the distance from 6v to 4v is not the same as 4v to 2v. I know it should be based on: $V = k\frac{q}{r}$.
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14 views

Why the magnitude, $E$, of the field vector is different for every sets of (parallel) plates?

This is quoted my textbook. I wonder why we can't reproduce the same magnitude on a different set of plates, if we make them the same size, same charge, and having the same electric potential, and ...
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1answer
45 views

Is the sea of electrons in a metal at rest when the metal is in electrostatic equilibrium?

It is said that charges inside a metal in electrostatic equilibrium are at rest, and are stationary. However, don’t the electrons have their own thermal vibrations and whatnot? Aren’t they always ...
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33 views

Earnshaw's theorm and Effective potential

Earnshaw's theorm says "no stable equilibrium for any $\frac{1}{r}$ potential field in charge-free space". Now I am confused in some aspects, and I would like some helping hands. 1.)General physics ...
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1answer
49 views

Why isn't the electric field zero in the empty space?

A spherical portion has been removed from solid sphere having a charge distributed uniformly in its volume the electric field inside the emptied space is? Isn't the electric field suppose to be zero ...
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1answer
19 views

Why does power loss in pure metal caused by temperature is calculated base on $P=I^2R$ but not $\frac{U^2}{R}$

$$P=I^2R=\frac{U^2}{R}$$ The metal's resistivity is temperature dependent, neglect the change in size by temperature. The power loss of a pure metal when it drop form temperature $T_1$ to $T_2$ is ...
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Is Gauss' law valid for time-dependent electric fields?

The Maxwell's equation $\boldsymbol{\nabla}\cdot \textbf{E}(\textbf{r})=\frac{\rho(\textbf{r})}{\epsilon_0}$ is derived from the Gauss law in electrostatics (which is in turn derived from Coulomb's ...
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1answer
41 views

Potentials of electrical multipoles vs strong interaction

Are there any reasons of the similarity? As I remember both potentials have the form $$\sim e^{-\alpha r}/r$$ where $r$ is the distance. The comment of Bort below led me to Wikipedia ...
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2answers
34 views

Electric Potential Between Two Like Charges

At the point horizontally across and equidistant from the centers of the two charges (also oriented horizontally), what is the electric potential? At that point, the electric field of the first charge ...
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0answers
8 views

Measuring Charge Density

I am running tests with metal electrodes and I am trying to find a value for charge density which I can use in calculations. If I have two vertical electrodes across which I am applying a voltage, how ...
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1answer
16 views

Zero of Electric Potential Energy

When you have a positive charge and a negative charge, the line that cuts perpendicularly between their separation distance is an equipotential line of 0 volts. The math indicates that at that point, ...
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2answers
40 views

Do permanent magnets have an electric current surrounding them?

Permanent magnets seems to have different properties to electromagnets, such that electromagnets can be used for induction and energy transfer if a conductor is placed within their changing magnetic ...
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0answers
20 views

Electic potential due to finite rectangular plate

I am trying to find the potential at any point (x,y,z) due to a rectangular plate with a constant surface charge density. Let's assume the plate is centered on the X-Y plane and extends from -n to n ...
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1answer
27 views

How do I get the angle for the $x$ and $y$ component of the electric field for four equidistant particles?

Four particles form a square of edge length $a= 5.00\ cm$ and have charges $q_1= +10\ nC$, $q_2=-20\ nC$, $q_3=20\ nC$, and $q_4=-10\ nC$. In unit vector notation, what is the net electric field the ...
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1answer
49 views

Interpretation of a term in the Maxwell stress tensor

With no magnetism, the $xx$ component of the Maxwell stress tensor $T$ is $$T_{xx} = \frac{1}{2}(E_x^2 - E_y^2 - E_z^2)$$ I can see why there should be a $+E_x^2$ term, but intuitively I don't see why ...
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1answer
54 views

Coulomb's law with an $r^3$, not $r^2$, in the denominator [duplicate]

I am reading an older physics book that my professor gave me. It is going over Coulomb's law and Gauss' theorem. However, the book gives both equations with an $r^3$, not $r^2$, in the denominator. ...
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1answer
35 views

Relation between permittivity of material and resistance [closed]

I am a class 12 student and trying to get some intuitive understanding on various quantities in electricity such a field, voltage, electro-static force etc. My text book has two formulas as follows: ...
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2answers
102 views

How does the conductor knows which side is outside?

For a electrostatic equilibrium state, we know charges only stay on the outer surface of the conductor. But, how does the conductor know which side is outside? If it's about the curvature, then ...
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Is the Coulomb's law the earliest formal equation of electricity? [migrated]

Is the Coulomb's law the earliest formal equation of electricity? Before Coulomb, many scientists and engineers conducted experiments of electricity.
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80 views

Principle of superposition and QED

For finding a net force on a charge when it is in influence of many charges we simply do vectorical addition of all individual interaction of that charge with others. That's what is principle of ...
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1answer
39 views

What is the strength of the magnetic field required to penetrate an average human body?

Introduction Suppose you are an experimental nanobot researcher trial-ling a new form of medication that involves activation and control of nanobots within the cells of the interior of the human body ...
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4answers
47 views

Why are excess charges in a conductor at the surface?

I’ve been told that coulomb repulsion pushes excess electrons to the surface of a conductor (i.e. sphere) electrostatic equilibrium, and this symmetry causes the net electric field inside to be zero. ...
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3answers
88 views

Gauss's law in a uniform charge distribution extending infinitely in all directions

Let us assume the universe filled with positive charge. About a particular point, all the positive charged particles will be symmetrical. Now consider a sphere of radius $r < \infty$ and apply ...
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2answers
53 views

Resistance of hollow metal sphere

A hollow metallic sphere has inner and outer radii $a$ and $b$ respectively. How to calculate its resistance between two a points $A$ (on the inner surface) and a point $B$ (on the outer surface)? ...
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1answer
40 views

How to calculate the potential energy of an $H_2$ molecule

From left to right, electron $e_1$, $e_2$ and proton $p_1$, $p_2$. $r_0=0.529nm$ The total energy is sum of energy require to bring each particle to its place. Take the place of $e_1$ is zero ...
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3answers
56 views

Is the electric field at a single point inside a charged sphere zero?

Many physics textbooks say, Gauss' law shows that the electric field inside a sphere with uniform charge distribution on the surface equals zero. What I want to know is, do they mean total, ...
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1answer
51 views

Work done by battery and potential energy of a capacitor

I have a doubt about the work done by a battery and the potential energy of a capacitor? 1- Consider a circuit where the capacitors are connected to the terminals of a battery. Through calculations ...
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3answers
97 views

Does a point charge exert force on itself?

Can a point charge feel the force of its own electric field? In various texts it is always mentioned about the force on a point charge in an external electric field. I think the particle does feel ...
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16 views

is there any element or material that ionized when pressure is applied to it?

I want to know if there is any material, that produce free electrons and ions when it undergoes to high pressure.
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1answer
36 views

Grounding a capacitor

When one of the plates of an isolated capacitor is grounded, does the charge become zero on that plate or just the charge on the outer surface become zero?
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1answer
18 views

From where do charges come to equify the potential of the sphere having less potential- through the wire or the sphere having higher potential?

Say, you have two different charged spheres having different potentials on their surface. Now you connect two of them by a wire. So, after sometimes, both of them will have the same potential on their ...
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1answer
38 views

A point charge near a conducting sphere

I was reading about method of images for a point charge near a conducting sphere. There(Feynman Lectures) I found this: What happens if we are interested in a sphere that is not at zero ...
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1answer
51 views

Force Acting on a Charge Between Parallel Plates

When a charge (say positive) is placed between an upper positively charged plate and a negatively charged plate, it should experience a repulsive force from the top plate and an attractive force to ...
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1answer
32 views

Why does the charge on the outer surface cancel the external field inside a conductor having a cavity filled with certain charge?

Let us take an arbitrary conductor having a weird-shaped cavity inside it. Let $+q$ charge be inserted inside the cavity. The field of $+q$ attracts negative charge & repels positive charge; ...
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0answers
22 views

Finding Magnitude and Direction of Dipole's Electric Field at a Point

This question pertains to finding the magnitude and direction of a dipole's electric field. Specifically, I am trying to figure out why we are using both the hypotenuse and $\sin\theta$, and not the ...
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4answers
62 views

Why, when and where is Gauss's law applicable?

Why is it said that Gauss's Law is mainly applicable for symmetric surfaces/bodies? Why not for asymmetric surfaces? I want a logical explanation! BTW my teacher said that Gauss's law is ...
3
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0answers
33 views

Why charge density is higher in the sharp edges of conductor? [duplicate]

If we have a conductor which is in electrostatic equilibrium, then the charge distribution over this surface $\sigma$ is greatest at the sharp edges of that surface. Why is this the case? It is ...
0
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1answer
51 views

Electric field of a plate with homogenous charge density

As an example for Gauß Law's application, one can find the calculation of an electric field of a plate with homogenous charge density in nearly every textbook: $$E = \frac{\sigma}{2\epsilon_0}$$ I do ...
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4answers
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Do electrostatic fields really obey “action at a distance”?

In an electromagnetic theory class, my professor introduced the concept of "action at a distance in physics". He said that: If two charges are at some very large distance, and if any one of the ...
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2answers
47 views

Charge enclosed by a Gaussian surface inside an uniformly charged thin sphere [duplicate]

Why is the electric field due to a charge enclosed by a Gaussian surface inside an uniformly charged thin spherical shell, zero?
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1answer
28 views

How are charges formed in clouds during lightning?

How are charges formed in clouds that are responsible for lightning?
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33 views

electric field inside hollow conducting bodies

Let's say that there's a hollow conducting sphere placed in the presence of an external electric field and there's a + ve charge placed inside the sphere at a point other than the centre of the ...
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1answer
35 views

Force acting on a dipole placed in a non-uniform electric field

Why does the net force acts in the direction of increasing electric field when an electric dipole is placed in a non-uniform electric field?
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1answer
70 views

Electric field due to an electric dipole at a point on the equatorial line

According to [tamilnadu][1] textbook Electric field due to an electric dipole at a point on the equatorial line is given as The direction of E is along ...