# Tag Info

### 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 ...

### 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 ...
Accepted

### 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 ...
1 vote

### 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 ...

### 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) ...

### 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 ...
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 ...

### 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 ...

### 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 ...

### 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 ...
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: ...
1 vote
Accepted

### 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 '...

### 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. ...

### 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 ...
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 ...

### 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 ...

### 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 ...
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.

### 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 ...
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 $$\phi(z) ... 0 votes Accepted ### Relation between Electric Potential and Electric Field Intensity The equation you're looking for is:$$\vec{E}=-\vec{\nabla}V$$If V depends on x only, the gradient becomes:$$\vec{E}=-V'(x)\vec{e}_x$$so \vec{E} is indeed zero in that interval. 0 votes ### Relation between Electric Potential and Electric Field Intensity The best you can do is to say that the component of the electric field in the x-direction is zero but there may be an electric field perpendicular to the x-direction (y and z directions). ... 2 votes ### Relation between Electric Potential and Electric Field Intensity Well, you called y the function V(x) which makes my answer awkward. We live in a three dimensional world, with coordinates, say x,z,w since I cannot use y... As you wrote dV = \vec{E}\cdot \... 1 vote ### Voltage propagation in neurons Biological processes can actively maintain electric fields, especially across cell membranes. The biggest fields are across the mitochondrial membrane within the cell, which plays a role in ... 1 vote Accepted ### Reduced electric field strength in a homogenous isotropic linear dielectric The electric displacement or electric flux density \mathbf{D} is related to the electric field \mathbf{E} by the constitutive relation$$\mathbf{D} = \bar{\mathbf{\varepsilon}}\mathbf{E}$$Where ... 1 vote Accepted ### Energy of a Continuous Charge Distribution You will soon see that the splitting of charge density and potential into 2 distinct elements, is the same as splitting E into 2 elements.$$\vec{E}_{total} = \vec{E}_{1} + \vec{E}_{2}W = \frac{1}...
The usual multipole expansion follows from the Legendre identity $${\frac {1}{\sqrt {1-2xt+t^{2}}}}=\sum _{n=0}^{\infty }P_{n}(x)t^{n}}$$ The generalization to arbitrary powers ...