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
101 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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1answer
14 views

Discharging a capacitor

Suppose I have a charged capacitor, meaning there's a voltage (electric potential difference), say, $2V$, between its two plates. We don't know the electirc potential of the individual plates, right? ...
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0answers
6 views

Electric field of a line charge, along itself

look at the pic : What is the electric field in along the line of charge with charge density $\lambda$ and length $L$. Is the electric field zero along the line without any difference in height?
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0answers
10 views

Quadrupole moment of point charges?

We know that due to expansion, the Quadrupole potential equals $$1/4\pi \epsilon r^3 . \int (r^\prime)^2(\frac32. \cos^2\theta^\prime-\frac12)\rho(r^\prime)d\tau$$ but what is the equation for point ...
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0answers
5 views

Quantitative measurement of electrostatic induction

How is it with the electrostatic induction measurement? Everywhere you can read about the effect of electrostatic induction but I still can't found any detailed explanations or quantitative ...
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2answers
37 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 [on hold]

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
15 views

Charge distribution in a conductor [on hold]

If some charge is given to a hollow conducting hemisphere of some thickness,where will be the charge present in that hollow conducting hemisphere?
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0answers
25 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 ...
2
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1answer
69 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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0answers
20 views

Doubts related to vertical circular motion in vertically upward electric field [on hold]

Suppose a simple pendulum bob has a charge and a vertically upward electric field is switched on.What must be the minimum velocity at top of circle to complete the circular motion? If electric field ...
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0answers
47 views

Gauss law problem [on hold]

Consider a cube in an variable electric field such that there is no charge enclosed by the cube.Say E = ax^(1/2) (where a is constant) (Base of cube is in the xz plane) and its direction is parallel ...
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0answers
27 views

Human Magnetic fields [on hold]

What exactly causes a person to be extremely sensitive to static electricity? Is it caused from windy days or certain fabrics your body injesting various precious metals, and slowly discharged from ...
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1answer
107 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
145 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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0answers
29 views

Electrodynamics [on hold]

I am having some trouble with this question. Why is there such a discrepancy? Is my reasoning correct? (this is my first time on such forums.. So kindly inform me if I am posting it at the wrong ...
4
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1answer
176 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
30 views

Radius of sphere formed by equipotential surface of point dipole [on hold]

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
901 views

Why is there lightning where there are no clouds? [on hold]

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
39 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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0answers
26 views

Energy stored in a charged capacitor [on hold]

There is a circuit with a 12.0 V cell and two capacitors with a switch, the switch in its initial position connects the cell and the first capacitor(4.7uF) (P) the switch in its second position ...
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4answers
174 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 ...
0
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1answer
132 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 ...
0
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1answer
185 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
57 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?
2
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1answer
104 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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0answers
20 views

Deriving coulomb's law [on hold]

Suppose you had two charges Q1 and Q2 a distance x away from eachother. I've been asked, given the equation for the potential energy between the two, to derive for force law for this (I'm not 100% ...
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2answers
154 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 ...
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1answer
19 views

Charge density on two hemispheres, enclosing a conducting sphere [closed]

Two uniformly charged non conducting hemispherical shells each having uniform charge density $\sigma$ and radius $R$ form a complete sphere (not stuck together) and surround a concentric spherical ...
0
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1answer
28 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 ...
1
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1answer
56 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
votes
2answers
73 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
194 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
53 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{...
2
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2answers
458 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 ...
4
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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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0answers
15 views

triboelectric effect at a liquid-liquid boundary?

In reading up on the triboelectric effect, most experiments deal with solid-solid interfaces. I've found some studies regarding solid-liquid boundaries, and even some engineering manuals outlining the ...
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0answers
46 views

Why do we integrate in the following derivation? [closed]

Electric potential due to a point charge. Let a point O have charge $q$ at a distance $x$ from point A and at a distance $r$ from point P ($r<x$). Suppose a test charge $q_1$ is placed at A force ...
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2answers
757 views

How does the magnetic field get induced in car's tire?

I was amazed to see how my car's tire started attracting the nuts and bolts, how in the world did it induce the magnetic field? Never heard of such phenomena!!!
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0answers
36 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 ...
3
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2answers
175 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 ...
1
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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
42 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 ...
0
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1answer
34 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{...
0
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1answer
42 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
38 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
36 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 $...
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0answers
30 views

Potential difference between a solid sphere and a shell [closed]

A solid conducting sphere having a charge $Q$ is surrounded by an uncharged concentric conducting spherical shell. The potential difference between the surface of solid sphere and the shell is $V$. ...
3
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0answers
44 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
25 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 ...