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Why doesn't when an electron gets knocked out of an atom, the electron get attracted back to the atom and reunite?

The electron is initially/always attracted to the nucleus but certainly can not combine with the nucleus (QM reasons and many answers on this site), also the electron has energy! When the electron is ...
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Doubt regarding an approach to derive the potential energy of two parallel dipoles

The potential energy is the energy needed to construct the system "from scratch", with the particles starting from infinitely far away. By assuming the field of the other dipole is fixed and ...
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Relation between Electrostatic Field and Electrostatic Potential at infinite

we observe that $E$ vs $r$ curve approaches $0$ faster than the later one, hence we can say that at some point when E becomes $0$, V will not be $0$ is a false statement. Try with numbers and report ...
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1 vote

Electric field at a point $P$ given a uniformly charged rod

It is not exactly true that the electric field lines point along the radial direction around the rod. It is true for the region of space that is located underneath or above the rod (i.e. from $x$ to $...
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Why doesn't when an electron gets knocked out of an atom, the electron get attracted back to the atom and reunite?

Most of these processes are governed by quantum mechanics, and in case of photovoltaic cells require some background in solid state physics and theory of electronic devices. Since the OP suggests no ...
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0 votes

Why doesn't when an electron gets knocked out of an atom, the electron get attracted back to the atom and reunite?

Why doesn't when an electron gets knocked out of an atom, the electron get attracted back to the atom and reunite? Electrons and atoms are in the quantum mechanical range, described by wavefunctions ...
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1 vote

Reasoning why the lightning shocks doesnt cause any shocks to a person inside car if the conditon is not fully electrostatic

The situation is nearly electrostatic/magnetostatic because the car is small compared to the lightning bolt. A pulse of lightning gathers its energy from a field that is kilometers in extent. At the ...
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0 votes

Understanding the effect of gravity in the electric field inside the conductor

of course, gravity technically has effects on anything with momentum. the way gravity works is by bending the space. in such a small scale, like an electron, the curvature of space around earth is ...
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-1 votes

Reasoning why the lightning shocks doesnt cause any shocks to a person inside car if the conditon is not fully electrostatic

lightning is an electrical current. this means it consists of an electrical carrier, carrying the electrical charge through a path. this path, starts from a highly charged cloud, and ends in the ...
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Can change in mass of charge, change value of charge (according to theory of relativity)?

We all know that for presence of charge it is necessary of presence of mass The word "mass" in this statement refers to the invariant mass. That is the usual meaning of "mass" as ...
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1 vote
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Problem 4.37 from Griffiths electrodynamics

I think none of the two captures the key to solving the problem. If you want to add potential of dipole and that of the rest dielectric part, how are you going to calculate the later? You will ...
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1 vote

Why, in this solution, acceleration is constant even when it depends on distance between two charges? I used integration of $a=dv/dt$ to solve this

The method used in the given solution is completely incorrect. Its only redeeming virtue is that it happens to give the correct answer through a numerical coincidence. The simplest way to solve the ...
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0 votes

Why, in this solution, acceleration is constant even when it depends on distance between two charges? I used integration of $a=dv/dt$ to solve this

The total change in field energy equals the negative of the total amount of work done on all charges. For 2 point charges, the total change in field energy is just the change in potential energy ...
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4 votes

Why, in this solution, acceleration is constant even when it depends on distance between two charges? I used integration of $a=dv/dt$ to solve this

Actually, acceleration is not constant in this case because in time $dt$ the force would change. So, the acceleration also changes even in time $dt$. I think the solution is wrong but the answer is ...
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0 votes

Can we calculate dipole moment about infinity?

Yes, if the total charge $Q$ is zero, the dipole moment $\mathbf{P}$ is independent of the point around which you're calculating it. This is because, for any two points $\mathbf{x}_1$ and $\mathbf{x}...
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Why are fields described as force divided by mass or charge?

Let me start by eliminating a possible misunderstanding. You wrote ...application of force on a body from a distance, like gravitational or electrostatic force is a two-step process, first, the field ...
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How did the expression for electric field?

Hi and welcome to physics stackexchange. Imagine you want to quantify how much force will a (test) charge feel if you place it somewhere near another charge, without considering the first (test) ...
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3 votes

Why are fields described as force divided by mass or charge?

Why are fields described as force divided by mass or charge? Because they follow from the classical universal law of gravitation and Coulomb's law. The force that each of two masses or charges ...
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1 vote

Why are fields described as force divided by mass or charge?

The definition of field, is there to tell us about the effects of the field on an object of unity value. most force fields have the parameter of the object they effect as a multiplier, hence when you ...
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Potential due to a spherical surface charge

First consider the triple angle identity: $$ cos3\theta=4{cos}^3\theta-3cos\theta$$ $$V_0(R,\theta)=kcos(3\theta)=k[4{cos}^3\theta-3cos\theta]=\frac{k}{5}(8P_3-3P_1)$$ For the potential inside up to ...
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Why is effect of charge redistribution not considered while calculating electrostatic forces between two charged bodies

There will indeed be some charge distribution when we consider two charged conductors and it will definitely affect the electrostatic force between the objects if they are close to each other. if both ...
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Charge density of Conductor

there are two sides to this question. the transient state and the steady state. in the steady state, as we know, in a conductor, the electrical field is always zero. the reason is the charges are free ...
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1 vote

Why the charge in each capacitors plate are equal in magnitude in series combination?

Suppose you have two capacitors in series like so: ————————||——————||———————— C1 C2 Consider only the central piece: ...
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1 vote
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The second uniqueness theorem in electrostatics

Thanks for posting this! I myself had a doubt that I couldn't resolve until I saw the theorem put this way. Still, what you said needs some important corrections/additions.. It actually proves (not '...
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0 votes

How does an electrical circuit works?

Very brief answer for you to do your own research: PD: is the amount of work that would be needed to move a unit charge from the negative terminal to the positive terminal, against the electric field. ...
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0 votes

How does an electrical circuit works?

The potential difference is a measure of how much is the difference between 2 points as voltage quantity. It can be measured for any element holding a resistance. Going back to the battery , the ...
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1 vote

How to solve the Gauss' law?

I don't quite understand this because there is not charge density, hence, no electric field. This is wrong. There can be a non-zero electric field $\vec E(\vec r)$ at a point $\vec r$ even when the ...
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What is the correct derivation of energy stored in parallel plates capacitor?

I'm not sure what you are saying, but the two derivations are equivalent with respect to the the total work required (total potential energy). In the first derivation the work per unit charge must be ...
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2 votes

How to solve the Gauss' law?

Ive been unfortunately trying to apply simple boundary conditions on your equation with no luck, because it's wrong. so First of all, let me correct you: Laplaces equation for $r-$dependance is: $$\...
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6 votes
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How to solve the Gauss' law?

You can have a non-zero potential -- as long as it is constant in space. This will always generate a zero electric field, since in this case $\mathbf{E} = -\nabla\phi = 0$, which is indeed expected ...
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0 votes

What is the correct derivation of energy stored in parallel plates capacitor?

You know that the electric field is conservative, so moving charges from infinity into two parallel plates separated by a given distance should require the same energy regardless of how you move the ...
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1 vote

Will the potential energy is same in both the cases?

Short answer: Not really. The answer is slightly different when talking about point charges vs distributons. Given I have some charge distribution $\rho_{1}$ and some other charge distribution $\rho_{...
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0 votes

Will the potential energy is same in both the cases?

I would think no, it wouldn't be the same. Having two charges already in position would alter the magnitude of the potential field for all the incoming charges- so it would require more or less work ...
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1 vote

Will the potential energy is same in both the cases?

It will be the same only if you ignore the electric field of the dQ's that you moved there first, that is, you only consider the electric field of the original charge Q at the origin. Otherwise you ...
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2 votes
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Electric field along axis of polarized cylinder

Your first argument makes sense to me, except one point: the surface bound charge density is $P(r)$ on the top and $-P(r)$ at the bottom. Regarding whether the displacement field $\vec{D}$ should be ...
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What is the meaning of potential of the capacitor?

What does this potential of the plates mean? Potential of a particular plate means the amount of work done in bringing a unit positive charge from infinity ($V=0$) to that particular plate. In your ...
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What is the meaning of potential of the capacitor?

Yes. $V_{1}$ and $V_{2}$ represent the potential due to the entire charge distribution. This is exactly the same as standard potential at a point in space. The difference in this potential $[V_{2}-V_{...
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0 votes

I can't seem to figure out a way to compute a gradient without reference coordinates

Use $\nabla\left[\frac{{\vec p}\cdot{\vec r}}{r^3}\right]$=$\frac{\nabla({\vec p}\cdot{\vec r})}{r^3}$+$({\vec p}\cdot{\vec r})\nabla\left(\frac{1}{r^3}\right)$. $\nabla({\vec p}\cdot {\vec r})={\vec ...
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1 vote
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I can't seem to figure out a way to compute a gradient without reference coordinates

We can use the identity $$\nabla(A\cdot B) = A \times (\nabla \times B) + B \times (\nabla \times A) + (A\cdot \nabla)B + (B\cdot \nabla) A$$ So, $$\nabla(-p_1 \cdot E_2) = \nabla[p_1 \cdot (\nabla V)]...
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0 votes

Why do I have to divide the total work in the method of images?

The purpose of the image charges is to help you calculate the electric potential and electric field in the region of interest. Introducing an image charge in (say) a region occupied by a conductor ...
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1 vote

How to identify electrostatic field function out of some given functions?

Calculate the curl of the vector functions ($\nabla \times \vec{v}$). The electrostatic field will have a zero curl.
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Mathematical rigorous definition for an electrical dipole

I think it can be intuitively understood as follows. The Dirac delta (for the Riemann-Stieltjes integral) is the point mass (for Lebesgue integration) and there is a Schwartz distribution version of ...
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Infinite conducting plane

Without knowing what happens at any other point, the solution is indeed non-unique. The potential has to obey Laplace's equation below and above the plane, so $$\phi''(z) = 0,$$ meaning that $$\phi(z) ...
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Relation between Electric Potential and Electric Field Intensity

The equation you're looking for is: $$\vec{E}=-\vec{\nabla}V$$ If $V$ depends on $x$ only, the gradient becomes: $$\vec{E}=-V'(x)\vec{e}_x$$ so $\vec{E}$ is indeed zero in that interval.
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Relation between Electric Potential and Electric Field Intensity

The best you can do is to say that the component of the electric field in the $x$-direction is zero but there may be an electric field perpendicular to the $x$-direction ($y$ and $z$ directions). ...
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2 votes

Relation between Electric Potential and Electric Field Intensity

Well, you called $y$ the function $V(x)$ which makes my answer awkward. We live in a three dimensional world, with coordinates, say $x,z,w$ since I cannot use $y$... As you wrote $dV = \vec{E}\cdot \...
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1 vote

Voltage propagation in neurons

Biological processes can actively maintain electric fields, especially across cell membranes. The biggest fields are across the mitochondrial membrane within the cell, which plays a role in ...
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1 vote
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Reduced electric field strength in a homogenous isotropic linear dielectric

The electric displacement or electric flux density $\mathbf{D}$ is related to the electric field $\mathbf{E}$ by the constitutive relation $$\mathbf{D} = \bar{\mathbf{\varepsilon}}\mathbf{E}$$ Where ...
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1 vote
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Energy of a Continuous Charge Distribution

You will soon see that the splitting of charge density and potential into 2 distinct elements, is the same as splitting E into 2 elements. $$\vec{E}_{total} = \vec{E}_{1} + \vec{E}_{2}$$ $$W = \frac{1}...
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4 votes
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How to find expansion of slightly modified Coulomb's potential?

The usual multipole expansion follows from the Legendre identity $$ {\displaystyle {\frac {1}{\sqrt {1-2xt+t^{2}}}}=\sum _{n=0}^{\infty }P_{n}(x)t^{n}} $$ The generalization to arbitrary powers ...
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