The Stack Overflow podcast is back! Listen to an interview with our new CEO.

Questions tagged [electric-fields]

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 of fields.

Filter by
Sorted by
Tagged with
0
votes
2answers
25 views

Direction of Uniform Electrical Field [on hold]

An electron is travelling in a straight line through a vacuum with a constant speed of $1.5 × 10^7\text{ ms}^{–1}$. The electron enters a uniform electric field at point A. The electron continues to ...
1
vote
1answer
35 views

Symmetry Argument of a Line Charge

I am been trying to make sense of my professor's lecture notes on where he talks about line charges; in general, I am lost when it comes to the symmetry argument in the case that $E_\phi=0$ on an ...
0
votes
1answer
32 views

Magnetic fields and electric fields relation [duplicate]

Why do we treat magnetic fields to be different from electric fields?.I thought special relativity had solved this thing.
7
votes
1answer
751 views

Electric field due to a hydrogen atom

Electric field due to two opposite charges According to the answers in the previous questions, if you separate the two charges from each other, they will produce a non-zero electric field ...
-1
votes
2answers
44 views

Electric field due to two opposite charges

We know that The net electric field due to two equal and oppsite charges is 0. But let us consider a charge +Q in an isolated system. An electric field E will be emitted by it. Similarly, a -Q ...
1
vote
1answer
32 views

Electric potential and its signs

When we are calculating the potential due to the sphere, why do we integrate from $r$ to $\infty$ instead of from $\infty$ to $r$? Or do we integrate from $r$ to $\infty$? Regardless of who does the ...
0
votes
0answers
24 views

Why are induced field lines circular?

Whenever we have a changing magnetic flux through a conductor an induced electric field is generated. It is often said that these induced electric field lines are circular in shape.But why is this so?...
0
votes
1answer
31 views

Gauss' Law not including all of the system

Suppose we have a system of two parallel conducting plates charges $Q$ and $-Q$ and charge densities $\sigma$ and $-\sigma$. In this case, to find the electric field, Gauss' Law is used with a ...
0
votes
2answers
56 views

In which situation does the electric field vary sinusoidally with position?

If I have a point charge q at the origin then the electric field will be $$ \mathbf{E} = \frac{1}{4\pi\epsilon_0} \frac{q}{r^2} \hat r $$ that is to say that electric field will diminish by the square ...
0
votes
1answer
41 views

Why do the sides of the Gaussian pillbox contribute nothing to the electric field? [on hold]

It says that the top and bottom of the pillbox contribute to the $E$ field but the sides don’t. I couldn’t quite understand this, please Help.
-1
votes
1answer
29 views

Why is electric field constant over the charged solid Gaussian sphere?

I saw this example at griffiths. It’s a basic question about gauss’s law but I saw the electric field being treated as a constant and thus, it got outside of the integral. I couldn’t quite understand ...
1
vote
0answers
31 views

What is the function $q$ in the definition of charge density?

Supposed we define $\lambda = \frac{dq}{dl}$. If I think of this intuitively, this makes sense; the linear charge density at a point is tiny amount of charge at that point divided by the tiny length ...
2
votes
1answer
21 views

Point with 0 electric field and non-zero potential

I'm quite new to physics and I don't totally understand the concepts of potential energy and work. I've been watching MIT courses and I got pretty confused, considering the following situation: We ...
0
votes
0answers
20 views

Leaked electric field in Transmission Line theory

In the previous image I can't understand why the leaked electric field in plate conductors is axial (On the same axis of propagation), And if it becomes axial then the wave in the conductor is not <...
-1
votes
0answers
51 views

Why is this equation correct?

This problem seems to be solved the exact same way in multiple solution books, so I'm certain that the way it is done is correct and that I'm just rusty when it comes to calculus due to multiple years ...
-1
votes
0answers
23 views

Is it (practically) possible to create non-uniform electrostatic in the form of a Fourier series?

Is it (practically) possible to create a non-uniform electrostatic field of the form $$E_x = \sum_{k=0}^N C_k e^{ikx}.$$ (keeping it in one dimension for simplicity) If yes, how?
0
votes
3answers
56 views

Why the magnetic field is perpendicular to the electric field?

I am a high school student. Recently I have read about magnetism. Each time I found magnetic field has to be perpendicular with electric field. Is there any explanation why is it?
-1
votes
0answers
48 views

Directly integrate $\mathbf{E}$ inside a spherical cavity in dielectric [closed]

P3-23 in Cheng E&M, 2nd edition: Determine the electric field intensity at the center of a small spherical cavity cur out of a large block of dielectric in which a polarization $\mathbf{P}$ ...
1
vote
2answers
63 views

Can a moving current carrying wire produce electric field?

As we know, a current carrying wire can create a magnetic field which is perpendicular to the direction of current (From relativity, we can understand why magnetic fields are produced ) and the net ...
-1
votes
1answer
25 views

Two point charges $Q_1$ and $Q_2$, are a distance a away from each other. Where is electric field zero? [closed]

Problem: Two different point charges $Q_1$ and $Q_2$ are a distance $a$ away from each other. The point charges are both positive. Where is the electric field zero? So far, I've found the total ...
0
votes
0answers
24 views

Gauss law in electrostatics

Consider a solid conductor,if the conductor makes a free electron inside that due to thermal energy ,so that causes one positive ion inside the conductor, my question is according to gauss law inside ...
2
votes
2answers
97 views

In electrostatics, $\nabla\times\mathbf E=0$. Why is this?

I can understand why this is mathematically but I do not understand the actual why, like in words why this is.
1
vote
3answers
49 views

$E$ outside a Metal Spherric Shell with a off-center Point Charge inside Shell

If a charge +Q is placed inside a metal shell (NOT at the center), as shown below. I can understand that E will be 0 between inner surface and outer surface due to this is a conductor. Then according ...
0
votes
1answer
32 views

What's the electric field in a sphere with charge $Q$ and an inverse linear/square law density of charge?

In Classical Electrodynamics by Jackson problem 1.4 asks to find the electric field as a function of the radius of a sphere charged with a charge Q and with a spherically symmetric density that goes ...
0
votes
3answers
47 views

How do we arrive on the same expression for Gauss's law when deriving it for a sphere or any other figure (say a cylinder)?

For a circular surface, the surface area of the circle is cancelled by factors in the denominator of $E$, leaving behind only $Q/\epsilon_0$. But what about when we conside a cylinder? How so we ...
0
votes
0answers
15 views

Is this calculator for the electric field inside of a square correct?

I made a desmos tool calculating the components of the electric field [u,v], at a point (a,b) inside of a square of continuously and uniformly distributed charge with linear charge density $c$. https:...
0
votes
0answers
16 views

Electric force on the interface between two dielectrics

Suppose two electrodes maintained at a voltage difference of $V_0$ are separated by a distance of $d=d_1+d_2$. Between the electrodes are two different dielectric medium of $\epsilon_1$ and $\...
0
votes
0answers
29 views

How to perform integration for all of space?

Two conducting spheres of radii $a$ and $b$ have charges $Q_1$ and $Q_2$. Distance between their centres is $R$. If ${\vec E_1}$ and ${\vec E_2}$ are electric field vectors due to the two spheres at ...
0
votes
4answers
100 views

Confusion about this simple electrostatics line integral

Suppose we want to find the electrostatic potential $\phi_{0}$, with reference to infinity, at $r_{0}$ resulting from a positive charge $q$ located at the origin. For simplicity, let us assume we are ...
2
votes
3answers
69 views

Do electric charges in an electric field move at a constant speed?

The electric field is given by: $$\vec{E} = \frac{1}{q}\vec{F}$$ Electric charges create an electric field which, in turn, creates a force that accelerates charges. The Ohm's law, however, tells us ...
0
votes
0answers
15 views

How should I express the force field acting on a ring in Thomson's jumping ring experiment?

I did Thomson's Jumping Ring Experiment with some additional factors added. I used aluminium rings of the same inner diameter, same thickness (at 2 mm), but varying outer diameter (starting from 65 mm ...
1
vote
1answer
42 views

Poisson's equation and electric field interpretation

My question is this: Are all solutions to Poisson's equation for a certain charge density such that the negative gradient of them will give me the electric field? In deriving the equation, we say ...
0
votes
2answers
64 views

Confusion about which electric flux is correct

Okay so electric flux density $\mathbf D$ is equal to the electric field multiplied by the permittivity of free space ($\mathbf D=\epsilon_0 \mathbf E \epsilon_r$). Therefore, $\mathbf D$ integrated ...
1
vote
2answers
48 views

Electric field inside the empty cavity of a thick spherical metallic shell subjected to a horizontal external electric field

Consider a thick metallic spherical shell of an inner radius $r=a$ and an outer radius $r=b$. Let an external electric field is applied horizontally ($\theta=\frac{\pi}{2}$ direction) from left to ...
0
votes
1answer
26 views

Electric Flux Through a cube

Let us consider a positive charge placed at a distance $x$ on left outside the cube of side $a$. The electric fields are entering the cube from left and exiting from the right. Will the flux in the ...
0
votes
2answers
41 views

What really is an electric/magnetic field?

Have you ever wondered how we can see this field or how it's formed its shape in space? I know we can feel that there's one by its effect which is the force. But what does it look like? We all know ...
0
votes
2answers
39 views

Electric Field Lines between two equal charges end at the midpoint, violate rule that lines only start/end at charge/infinity

At the midpoint of the line joining two equal point charges, the field is zero, and the electric field lines on this line joining the charges each begin at a charge and kind of end at the midpoint. ...
0
votes
2answers
46 views

How can a spring contract when magnetic field cannot do work?

When a spring is kept in a magnetic field and current is passed through it, its edges act as parallel conductors and due to the action of Lorentz force, they pull themselves together. A spring ...
0
votes
1answer
35 views

Electric Field inside an ideal conductor

I have some doubts about the electric field inside an ideal conductor (let's call it E). Precisely, I have read two different descriptions 1) On physics books I read that the electric field inside in ...
0
votes
2answers
39 views

Visualization of electromagnetic waves with potentials?

I wonder if there is out there any visualization of the propagation of electromagnetic waves, not only with the electric and magnetic fields components but an actual visualization of the underlying ...
1
vote
1answer
16 views

Using Trig Substitution for calculating the Electric Field with 3 variables in the denominator

I am reading how to calculate the Electric field for an infinite plane of charge that happens to be in the xy plane. The equation sets up as $$E = \frac{\sigma }{4\pi \varepsilon }\int_{-\infty }^{...
0
votes
1answer
28 views

Electric field lines of a semi-circle charged ring

If I have semi-circle positive charged ring, the electric field lines should come out the outer curved side of the ring radially. What about the inner curved side? According to what I learnt (or in ...
1
vote
1answer
49 views

Why can we use Gauss' law to show that the field inside a spherical shell is zero?

I've read through the standard explanation of the electric field due to a spherical shell with uniform charge density. This explanation argues that because a Gaussian surface inside the shell encloses ...
3
votes
1answer
48 views

Why does the interaction energy for the electric fields of two point charges vanish over any shell smaller than their separation?

A previous question, A triple integral in Spherical coordinates from Jackson's book on Electrodynamics, presents the fairly routine calculation of the interaction energy encoded in the cross-term ...
-4
votes
1answer
74 views

What does $e$, $i$ and $\vec{p}$ mean in this formula? [closed]

I've found a formula to calculate the $\vec{E}$-field vector of a Hertzian dipole in the far field (don't know if that's the correct term) to draw and simulate the field lines. Link to my source: ...
2
votes
0answers
44 views

The $z$-component of the electric field vector [closed]

It is asked to find the wave equation for the z-component of the electric field vector by using Maxwell’s equations in free space. Here is my work - In free space we have the following relation ...
2
votes
2answers
88 views

Difference between $E$ and $D$ in conservative fields

I am having a tough time visualizing the derivation of boundary conditions in Electrostatics. My main problem lies with the fact $\oint \mathbf E\cdot \text d\mathbf l = 0$ is used instead of $\oint \...
0
votes
1answer
34 views

What will magnitude of the net force on any of the charges be?

When identical point charges are placed at the vertices of a cube of edge length $a$, each of them experiences a net force of magnitude $F$. Now these charges are placed on the vertices of another ...
4
votes
1answer
118 views

Why can't we generate electricity from Earth's electric field?

This may be very silly, but I need to understand this to get my concepts right. Consider the fact that the electric field b/w the Earth's surface and the ionosphere is on an average $100$ V/m, then ...
2
votes
1answer
52 views

Is electric potential always continuous?

In electromagnetism, we say that any conservative electric field $\vec{E}(\vec{r})$ is associated to a scalar potential $V(\vec{r})$ such that $\vec{E}(\vec{r}) = -\nabla V(\vec{r})$. If the electric ...