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 [tag:magnetic-...

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1answer
111 views

Can I create a static electricity water magnet?

I came to watch a video that water dipole get attracted by static electricity. I wanted to know if I could make a static electricity device that could pull out all the water from a wet cloth.
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2answers
56 views

Electric Potential produced by Hollow Sphere

Let there be a hollow sphere (Throughout the question we will ignore the thickness of the sphere) which is positively uniformly charged,q of radius, R. Suppose there to be a test positive charge, q' ...
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0answers
7 views

Rusting of induction hardened portion when the non hardened portion is chrome plated [closed]

When a ferritic steel component that has a portion of it induction hardened and quenched in oil is chrome plated over the non hardened portion, I see rust formation after some time on the induction ...
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0answers
31 views

Regarding the zero internal electric field in a conductor (electrostatic case)

Let's say we have a homogenous electric field in the $z$-direction. For computational simplicity let's say we have a thin sheet of metal covering entire the $x$-$y$ plane. The answer here is straight ...
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1answer
71 views

Why does the divergence of the Poynting vector have energy flux density?

The poynting vector is defined as $\vec{S}=\mu_{0}^{-1}\vec{E}\times \vec{B}$ Taking the divergence of the poynting vector, one arrives at $\vec{\nabla} \cdot \vec{S}=-\frac{\partial u}{\...
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1answer
109 views

Gauss' Law and enclosed charge

In Halliday and Resnick, I am asked to find the charge on a drum (a cylinder) given the electric field very close to the drum. In the solutions manual, the author appears to enclose the drum with a ...
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2answers
149 views

dipole-dipole interaction

U= -p(vector of one dipole)*electrict field due to the second dipole does this equation give the energy of one dipole due to the electric field due to the second one, if so is the total ...
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1answer
188 views

Electric Potential Field of Parallel Electrodes within Grounded Shell

Any help would be greatly appreciated I think I need to solve this using boundary potential conditions and Laplace equations. Here is the system I'm attempting to model: The red rods are metal ...
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2answers
32 views

Radius of sphere formed by equipotential surface of point dipole [closed]

One of the Equipotential surface formed by point electric dipole placed in parallel electric field forms a sphere enclosing the dipole.how to find the radius of the sphere?
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2answers
1k views

Why is there lightning where there are no clouds? [closed]

Recently my family and I went onto the balcony to observed the stars in the night sky. We started to see flashes in the sky and we realized that it was lightning (non-fork lightning). I looked around ...
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3answers
47 views

Charged Particles: How is energy conserved?

I can seem to understand where the energy comes from when two particles accelerate. I tried searching through the forums and it seems like the answer is always potential energy was the source of ...
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4answers
189 views

Why is the total potential difference in a circuit the sum of the individual potential differences?

I am having difficulty in applying my understanding of electrical potential to circuits. Why is the total potential difference in a circuit the sum of the individual potential differences among ...
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1answer
140 views

Induced charge due to charge distribution between two plates

I am trying to work through this problem: given two parallel square conducting plates (side w), one grounded(at x=0) and the other held at +V (at x=L where L < < w), and there is a charge ...
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1answer
197 views

Two concentric conducting shells connected by wire with modified Coulomb law?

This question is related to this one, but is a bit different. Consider two concentric and conducting spherical shells connected by a wire. Inner shell has radius $b$ and (unknown) charge $q_b$ while ...
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2answers
93 views

Torque on electric dipole placed in non uniform electric field

When electric dipole placed in non uniform electric field, what is the approach to calculate torque acting on it? Can it be zero?
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1answer
126 views

What is the significance of the Inverse-square law? [duplicate]

Considering its occurrences in various fields like Electrostatics, Gravitation, Acoustics etc. how does the law bind these topics together?
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2answers
156 views

electrostatics and magnetism

Let a square loop be placed in a uniform electric field in a position of stable equilibrium. Then, because of the electric field, if the electric field is in the rightward direction then a positive ...
0
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1answer
30 views

Electric Field of Bar [closed]

Problem: Positive charge $+Q$ is distributed uniformly along the positive $x$ axis from $x = 0$ to $x = a$. Negative charge $-Q$ is distributed along the $-x$ axis from $x = 0$ to $x = -a$. A point ...
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1answer
63 views

Can we derive Biot Savart law from Coulomb's law?

Can we derive Biot Savart law from Coulomb's law by setting a current source at an instant in place of one of the charges? Let's say $dl$ is the length of the conductor having $dQ$ charge which ...
4
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1answer
80 views

Electric field due to a charged irregularly shaped balloon

There is a question in my textbook that says: A rubber balloon is given a charge $Q$ distributed uniformly over its surface. Is the field inside the balloon zero everywhere if the balloon does not ...
0
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1answer
201 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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2answers
54 views

Electric Field of a Disk an Infinite Distance Away

The electric field of radius $R$ and a uniform positive surface charge density $\sigma$ at a distance $x$ from its center is given as $$E = \frac{\sigma}{2 \epsilon_0}\left( 1 - \frac{1}{\left(\frac{...
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2answers
473 views

What is Gauss's Law in two dimensions?

I am trying to figure out how the equation for the field if a Gaussian surface was applied to a 2D plane. I did see another question already asked on the subject, but I didn't get a particular ...
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3answers
5k views

Electric field and electric potential of a point charge in 2D and 1D

in 3D, electric field of a piont charge is inversely proportional to the square of distance while the potential is inversely proportional to distance. We can derive it from Coulomb's law. however, I ...
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1answer
37 views

Weight of sphere in kerosene [closed]

Two identically charged spheres are suspended by strings of equal length. When they immersed in kerosene, the angle between their string remains the same as it was in the air. Find the density of the ...
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2answers
187 views

Charging by induction

When we charge an conductor by induction and grounding, we first bring a negative charge to the conductor. As a result the mobile electrons of the conductor get repelled and stay far from the negative ...
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1answer
1k views

Electric field from conductive to dielectric media

I am interested in the main difference between transitions from electric fields from Conductive to Conductive/ Dielectric to Dielectric and Dielectric/Conductive media. What are the boundary ...
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0answers
45 views

What one would observe on extremely high voltages?

I am interested which physical processes generate the highest electrical voltage and what the highest measured voltage is. In everyday life, electrostatic charges e.g. while walking with socks on a ...
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1answer
38 views

Derivation of dipole moment of array of point charges

This question is about the equation describing the net dipole moment for an arbitrary number of point charges. Here's what I understand: For two point charges $q$ and $-q$ with positions $\mathbf{...
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1answer
53 views

Total chemical potential of electrons in pn junction

I am reading this page about electron energy concept terminology. I am trying to apply that for the pn junction in equilibrium below. Could anyone help me to see if I get it correctly? C = ...
0
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1answer
39 views

Poisson's equation with point source

PDE's are not my thing, but I'm trying to calculate the voltage in a finite conducting sphere, based on a point current source. With Poisson's equation of $\nabla^2\Phi = -\frac{J}{\sigma}$, where $J$...
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1answer
43 views

What are dimensions of co-ordinates which are used to define an electric field?

A possible electrostatic field is: $ E_x = 6xy$ $ E_y = 3x^2-3y^2$ $ E_z = 0$ Suppose we are using SI system. So unit for components of field is volts/meter. Then what are dimensions of $x$ and $...
3
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0answers
47 views

Is it true that it is a misconception that the Van de Graaf generator works with the Faraday's ice pail principle

I found some interesting papers which claim that it is a misconception that the charge accumulation on the top is due to the Faraday's ice pail principle but rather just as in Volta's condensing ...
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0answers
27 views

Simple Van de Graaff generator with friction only

I have found an interesting picture about different versions of the Van de Graaff generator: (Source: http://www.coe.ufrj.br/~acmq/vdgself.jpg) I know the Wimshurst system on the right but I have ...
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1answer
37 views

main cause of self charging of unshorted capacitors?

In the lab, we keep all of the high voltage capacitors shorted when not in use, and rightfully so. They tend to spontaneously charge when left for some time and become extremely dangerous. while the ...
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1answer
12 views

How do ink droplets passing through two charged metal plates become charged as well?

In the working mechanism of an inkjet printer, I came to know that ink droplets in the form of a stream pass through two charged parallel metal plates ( like a parallel plate capacitor) and while ...
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2answers
35 views

Electric field of uniformly charged plane

Which are the null components (in a Cartesian coordinate system) of the Electric field of uniformly charged plane in $x=0$? I consider the coordinates : $(x,y,z)$ I think that $E_x = 0$, $E_y \ne 0$, ...
2
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2answers
3k views

The electric field of a conductive sphere containing a charge - grounded vs not grounded

Let's suppose we have a sphere but unlike theoretical ones it'll have some thickness say $\Delta r$ and inner radius $R$. What I was wondering about is how will it behave if we place some charge $q$ ...
2
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3answers
916 views

Dielectric slab counter-intuitive formula?

For the calculation of force on one of the two equal(in magnitude, opposite in sign) point charges separated by $r$ with a dielectric slab of dielectric constant $K$ and width $d$ in between, the ...
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2answers
62 views

Energy of electric field and magnetic field

I am studying about inductors and capacitors. They store their energy in the form of electric field and magnetic field.Energy is required to create fields.But if we take an isolated charge and nothing ...
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3answers
43 views

Dipole Moment and separation

My understanding of a dipole moment is it defines the strength of various dipole interactions, eg the common example of torque in an electric field. My confusion stems from the fact that the magnitude ...
4
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1answer
598 views

Finding Green function using eigenfunction expansion method

Given the Dirichlet boundary condition, I am to show that the functions that satisfy $$(\nabla ^2 + k_{lmn}^2) \psi_{lmn} (x,y,z) = 0$$ are given by $$\psi_{lmn} = (\frac{\pi}{2x})^{1/2} J_{l+...
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1answer
170 views

Is putting a charged balloon up to a neutral wall polarization AND temporary induction, or just polarization?

Is putting a balloon that is charged up against a wall and having it stick polarization AND charging by temporary induction, or just polarization?
0
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1answer
25 views

What does negative potential at a point signifies?

I am am bit confused in the concept of electric potential. Does this means there is a decrease in the potential energy. Suppose a point has( - 40V) potential, does this means that the place from ...
0
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1answer
170 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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0answers
55 views

Electric potential due to surface charge distribution on a conducting sphere

Let's consider a conducting sphere. If we charge the sphere, it is understood that there will form a surface charge distribution such that the surface of the sphere is an equipotential surface $ 0=\...
1
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3answers
86 views

Why doesn't $E$ depend on $x$?

Suppose that in $\mathbb{R}^3$ the infinite yz-plane is charged with a superficial charge density of $\sigma$. Then I have calculated that the electric field is equal to $E=sgn(x)\frac{\sigma}{2\...
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1answer
116 views

In the case of two equally charged particles, is the electric field between them incompressible? [closed]

When approach two electrons (or two protons or ...), the electric fields do not merge and stay isolated from each other. Which I borrowed from here. Is it right to conclude that in the case of ...
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1answer
29 views

Force between plates of a capacitor with dielectric a battery

My teacher told me that the force will increase $k^2$ times, where $k$ is the dielectric constant, but I don't see how. To start with, with no dielectric, the force between the plates is given by $\...
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2answers
130 views