For questions that utilize the concept of electric fields (commonly denoted by the letter E), or for questions whose answers likely involve electric fields. More specific than the [tag:electricity], as questions about the phenomenon & theory of electricity do not necessarily involve the discussion ...

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1answer
52 views

Doubt in derivation of electric field at axial snd equatorial point

Firstly, in derivation of electric field at an axial point due to a dipole we have to determine the Electric field at a point P on the axial. So there are two electric fields acting on this Point P, E(...
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0answers
83 views

Electric field at centre of two different hemispheres

I have a sphere separated into two hemispheres which are insulated from each other the bottom half is earthed and the top half has potential $V$. Radius=$a$. I am trying to find the Electric ...
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1answer
22 views

Work in electric field - formula

Suppose there's a electric field generated by a charge $Q$. If I moved a charge $q$ placed at distance $r_1$ away from $Q$ to distance $r_2$, supposedly the average force acting on $q$ will be: $F=\...
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1answer
53 views

How to determine the cylindrical gaussian surfaces position while finding the electric field?

Today I encountered a question that had the solution: electric field outside of a charged nonconductor is $$ E=\frac{\sigma}{2\epsilon_0} $$ which had the diagram below: Fig. 1 and for the ...
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0answers
19 views

Voltage drop along electron beam

A focused electron beam represents a current and unless the charges (electrons) meet no resistance to their movement there should be a voltage drop along the length of the beam. So, assuming the beam ...
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1answer
64 views

Electric field integration? [closed]

If we have a rod uniformly charged with $Q$ stretching from $-a$ to $a$ on the $x$-axis as shown in the picture And we want to calculate electric field in point $2a$ on the $x$-axis, we know that ...
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1answer
90 views

How does an Atoms electric field overcome an electrons inertia?

An electron has mass, and therefore has inertia. How does an atoms electric field perpetually overcome an electrons inertia, necessary to hold it in its shell? Does this require continual work to be ...
-1
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1answer
106 views

Capacitors and external electric fields

I am grading questions from the lab manual provided by the professor to review with the students. I am trying to wrap my head around one of the questions about what an external electric field would ...
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0answers
23 views

Separating Interaction of Heat from Electricity?

I have a rod where electricity of frequencies 1-360 Hz is passed through. It is affected by heat. I am evaluating the energy involved in such a process, contributed by electricity and heat. The ...
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2answers
190 views

Velocity selector and charge to mass ratio of an electron

I recently read that J.J. Thompson used a velocity selector to find the charge to mass ratio of an electron. Having learnt the principle behind the velocity selector, I see no relation between these ...
3
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1answer
76 views

How does parallel plate lose energy when deflecting charged particles

Say you have a parallel plate setup, each plate is charged with ±Q of charge, and is then disconnected from the power source and is insulated from the environment. There is no way the plates can be ...
2
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0answers
56 views

Gauss' Law and Electric Field Close to a Ball

So I've learned about Gauss' law and I have something in my head. Why does electric field that is very close to a ball is not close to infinity. Take a look at this image: As we can see, if we make ...
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0answers
36 views

Linear Charge distribution in thin (conduction) beam due to electric field

I'm trying to figure out the linear charge density in a very, very thin conductive beam of 0 net charge due to an electric field generated by a source very, very far away. Since the beam is ...
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1answer
60 views

Eddy current induce emf

Q1Suppose there is a wire having AC current so as ac current is alternating it creates back emf wether that back emf produces current ?? If yes then that current is same as eddy current or not?? ...
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2answers
38 views

Electric fields with different frequencies, total intensity?

What happens when electric fields with different frequencies are combined? Is it possible to calculate the intensity of the total electric field? For a project, I need to simulate a brain treated ...
2
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0answers
25 views

Symmetry arguments and plane sheet of charge [duplicate]

The electric field due to a infinite plane sheet of charge is given by $\sigma/\epsilon_o$. Now could we have deduced by symmetry that the electric field's magnitude won't depend on distance?
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1answer
41 views

Charge outside a Sphere given charge density

If a sphere has a charge density of $\rho =\alpha r^2$, I want to calculate the Electric field outside of the sphere. Starting with Maxwell's equation $\bigtriangledown\cdot E=\frac{\rho }{\epsilon ...
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3answers
61 views

relation between amplitude and frequency of a rotating electric field [closed]

I generated a rotating electric field produced by Ex=cos(wt) Ey=cos(wt-pi/2) in x and y directions. I ran a simulation and seems only in certain amplitudes and frequencies it makes a rotating field. ...
3
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2answers
84 views

Some confusions regarding electrostatic shielding

A spherical conductor A contains two spherical cavities as shown. The total charge on conductor itself is zero. However, there is a point charge q1 at the centre of one cavity and q2 at the centre of ...
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0answers
23 views

strength of each dipole charge

If I have a two dimensional dipole whose line charges are located on the y axis, I know that the electric flux through a gaussian pill box containing both the charges will be zero, that is \begin{...
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1answer
76 views

A question when using $E= - \nabla V$

This problem is from Problems and Solutions on Electromagnetism. A thin but very massive disc of insulator has surface charge density $\sigma$ and radius $R$. A point charge $+Q$ is on the axis of ...
8
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4answers
263 views

Maxwell Equations don't give unique Electric Field?

Consider the class of electric fields given by $$\mathbf{E}=\begin{cases} \ln (Cr)\hat{z} & 0\leq r < R\\ 0 & r> R \end{cases}$$ where $C$ is a constant and $r$ is the polar-distance ...
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0answers
59 views

Force Exerting on a magnetic train

A question is already asked ( How does this “simple” electric train work? ). But I've got a question about it. In order to calculate the force which is being exerted on the system including magnets ...
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2answers
46 views

How can the position of charge be determined without EM waves?

The EM waves produced by accelerating charges can perhaps be used to locate the position of the charge, as usually done with the de Broglie waves. The stronger the oscillations of the electric and ...
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1answer
104 views

if there is no electric field then any charge exists or not? [closed]

If we assume a region of space in which there is no electric field, can we say that no electric charge exists? I think that there is no electric charge particles to create electric field for this ...
2
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0answers
64 views

Van der pauw method for an isolated hole

Van der pauw method is a way to measure the resistivity of a material with arbitrary shape while it meets some specifications ( being homogeneous and ...). One of the conditions is that the sample ...
2
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2answers
133 views

How virtual photons give rise to electric and/or magnetic field? [duplicate]

Say a neutron which have magnetic moment despite carrying no charge. Isn't both the electric field and magnetic field consist of virtual photons? So how can the same virtual photons give rise to 2 ...
1
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1answer
41 views

Why don't simple circuits cause the electrical breakdown of air surrounding them?

Electrical breakdown of air occurs when the electric field exerted by a charged object exceeds the electrical breakdown limit of air which is $3.10^6 V/m$. Since even 1 Coulomb of charge can exert an ...
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1answer
59 views

How and why do electric fields occur when we put a voltage difference between two point?

When we put a voltage differences between two points on a certain sample, I would like to know how and why the electric field occurs. In addition, I would like to know in what shape does the electric ...
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0answers
93 views

Which scientist is this?

Okay so I was watching discovery channel, in that i saw a man cleaning live electric wires of 10k volts in the air, he was not touching the ground. They said he was able to do this because of the "law"...
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0answers
29 views

Theoretical model of MRI scanner

Recently I have gained strong interest in studying the Physics of an MRI scanner. Most of the physics resources I have found are strongly practically orientated and do not so much approach the ...
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2answers
57 views

electric field inside a conducting body [closed]

From Gauss' Law, we know that the electric field inside a solid conducting sphere varies linearly with the distance from the centre. But we also know that electric field inside a conductor is zero. ...
0
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1answer
61 views

What does the tangent line to a general curved electric field line denote?

Just want to see the tangent line which indicates the line of electric force. What is tangent line?
0
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1answer
57 views

Electric field's area [closed]

How much area an electric field surrounds? since we're just able to draw the electric lines of force we sometimes think that the field is though 3d but surrounds a finite area. But is it measurable or ...
0
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2answers
121 views

Electric flux density between the 2 plates of a capacitor

I am reading a solved exercise about a parallel plate capacitor in which states that the electric flux density between the 2 plates is: $$D=p_{s}$$ where $p_{s}$ is the surface current density of ...
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0answers
30 views

Potential difference across a resistor

I would like to know if the potential difference between the two ends of the resistance is same as the potential difference between any tow points in the resistance whose length is smaller than the ...
4
votes
2answers
103 views

Kirchoff's rules and inductance

Can Kirchoff's loop rule be applied in a scenario involving an inductor? Kirchoff's loop rule states that the closed loop integral of E dot dl is equal to zero. But, in a situation with an inductor, a ...
3
votes
1answer
41 views

Is there an electric field within a superconducting inductor?

I have learned that the magnitude of the EMF (potential difference) between the terminals of an inductor is equal to L*di/dt. Does this imply that an electric field does indeed exist in an ideal ...
0
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1answer
51 views

Electric field along a wire and load

I have referred to many books and all of them apply loss in potential across a resistor only in case of circuits. However, the electric field is present in the whole conductor. Hence the electrons ...
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1answer
42 views

Electron gun; potentials around charged plates

I know that an electron gun releases electrons by thermionic emission and accelerate the electron through charged plates, and that the electrons are not gaining any energy after they leave the gap ...
1
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1answer
39 views

Uniform Electric field cannot propagate a wave of finite wavelength? [closed]

While going through the proof of the transverse nature of electromagnetic waves using gauss' law for electricity, I encountered a statement that I couldn't comprehend. They used an argument that ...
4
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0answers
55 views

Lightning sprites

Lightning usually occurs due to an electrostatic discharge between an electrically-charged cloud and the Earth's surface, or between clouds. There are also sprites, electrical discharges that occur ...
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0answers
26 views

Is the electric field inside a conductor always zero? [duplicate]

We just learned in physics that a field inside a conductor is zero. My question is, is this always true? For example, what about if you were inside a hollow iron sphere 10 feet from a hugely ...
1
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1answer
93 views

Electric field of a moving charge with Lorentz transormation

I was going through this link http://physics.weber.edu/schroeder/mrr/MRRtalk.html There it says Now consider the electrostatic field of a point charge at rest, shown at left below. At every ...
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0answers
11 views

Electrode configuration when radially poling piezoelectric material?

All the information on the web I have come across WRT poling piezoelectric material usually assumes a uniform field (such as between two plates). I would like to pole a cylinder so that the reverse ...
2
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0answers
34 views

Spherical charge distribution [closed]

I have a pretty simple exercise but i can't get it right using both integration and divergence of potential. I first did the field inside the sphere: $$\vec{E} = \frac{Q\vec{a_R}}{4\pi^2\...
1
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1answer
98 views

Number of electric field lines and intensity of electric field

I´m currently studying electrostatics and I´m having a hard time understanding why do the number of electric field lines is proportional to the intensity of electric field? I just don´t see it. Can ...
6
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4answers
1k views

Why is there an electric field in a wire even though it is a conductor?

If you take a perfect conductor, there cannot be a field across it since if there were, the particles would arrange themselves in a way to cancel out the field right? Yet, why does the same not hold ...
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0answers
31 views

Corona discharge leading to hexagonal structure

Hexagons appear many times in nature, and I'd like to know why they appear in this situation too. Somebody has already been kind enough to help me figure out why this phenomenon occurs - it is due to ...
1
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1answer
110 views

Electric flux density for a hollow cylinder using Gauss's law [closed]

In the textbook of "Engineering Electromagnetics": I understood it except the part highlighted with yellow(i.e. how did he find the charge distribution of the outer cylinder? What are the ...