The electric-field tag has no wiki summary.
2
votes
1answer
195 views
Existence Of Electric Field Lines
Can an Electric Field with field lines Like So Exist:
One Of my friends said it couldn't as the field lines here are not conservative ; so it cannot exist ; Is he right?
Or can it be made to ...
0
votes
1answer
195 views
Equipotential Contour mapping and making it 3D [closed]
I have seen Contour diagrams for Equipotentials . That are drawn like so:
I also saw One image for these contours that was in 3D (Negative Point Charge) :
I was Wondering If there's any ...
0
votes
2answers
396 views
Electricity & Magnetism - Is an electric field infinite?
The inverse square law for an electric field is:
$$
E = \frac{Q}{4\pi\varepsilon_{0}r^2}
$$
Here: $$\frac{Q}{\varepsilon_{0}}$$
is the source strength of the charge. It is the point charge divided ...
0
votes
1answer
88 views
$\mu$T in to $\frac{W}{m^2}$ (for interpreting EMF readings)
I am considering purchasing an EMF reader, to collect data about what is being thrown off of power lines and various other sources in the house to reach some conclusions.
An issue is, the meter can ...
-1
votes
2answers
184 views
Why do you get electric field of a light wave?
Why do you get electric field of a light wave in following form: $E(x,t)=A cos(kx-\omega t- \theta)$?( look at: https://public.me.com/ricktrebino -> OpticsI-02-Waves-Fields.ppt, p. 18)
1
vote
2answers
448 views
A closed surface, no charge enclosed, yet flux not 0?
!
The book says it is $E_0\pi r^2$ because the flux through the circle is equal to the curved part of the paraboloid.
I don't understand this, shouldn't the total flux be 0 for the whole surface? ...
0
votes
0answers
178 views
Calculating the number of turns and thickness of an electromagnet
I want to calculate the number of turns of an electromagnet and the thickness of the wire.
But i have tried to search arround in books, and can't really find any thing.
I know my wire is 0,114mm and ...
3
votes
1answer
2k views
Why we cannot use Gauss's Law to find the Electric Field of a finite-length charged wire?
One of my physics books has a nice example on how to use Gauss's Law to find the electric field of a long (infinite) charged wire. However, at the very end of the example, the author ends by saying ...
0
votes
2answers
295 views
Electric fields in/around conductors
So according to my notes, the field inside a conductor is zero. But what, exactly, is meant by inside?
I think we are in electrostatics for the purpose of this question.
The reason it is zero is ...
0
votes
2answers
898 views
Derivation of Electric Force between Parallel Plates
So the electric field between two parallel plates is given by $E = V/d.$ How do you derive this?
0
votes
0answers
459 views
Rotating Disc and Magnetic Field [closed]
I'm studying for exams, and I am curious as to how the rotation of a disc would affect the magnetic field. The following problem stumps me:
A plastic disc of radius $R$ has a charge $q$ uniformly ...
4
votes
3answers
963 views
“Find the net force the southern hemisphere of a uniformly charged sphere exerts on the northern hemisphere”
This is Griffiths, Introduction to Electrodynamics, 2.43, if you have the book.
The problem states Find the net force that the southern hemisphere of a uniformly charged sphere exerts on the ...
5
votes
3answers
813 views
Charge Distribution on a Parallel Plate Capacitor
If a parallel plate capacitor is formed by placing two infinite grounded conducting sheets, one at potential $V_1$ and another at $V_2$, a distance $d$ away from each other, then the charge on either ...
3
votes
4answers
2k views
In electrostatics, why the conductor is an equipotential surface?
Since the electric field inside a conductor is zero that means the potential is constant inside a conductor, which means the "inside" of a conductor is an equipotential region.
Why books conclude ...
2
votes
3answers
4k views
In electrostatics, why the electric field inside a conductor is zero?
In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero.
I ...
0
votes
1answer
456 views
Where will the electric field be zero in dipole [closed]
Lets say we have an electric dipole. I can't figure out where the location of net zero electric field will be.
Tnx
0
votes
2answers
455 views
Boundary conditions for static electric field
Consider a surface that carries surface charge density. In electrostatics, boundary conditions are studied by showing that there is a discontinuity in the normal component of the electric field across ...
3
votes
1answer
95 views
Scaling of Static Electric Field
The electric field of a point charge goes like $\displaystyle\frac{1}{r^2}$
The electric field of an infinite line goes like $\displaystyle\frac{1}{s}$
The electric field of an infinite plane is ...
1
vote
1answer
270 views
Electric Flux Density - Ring Charge
A ring placed along $y^{2}$ + $z^{2}$ = 4, x = 0 carries a uniform charge of 5 $\mu$C/m. Find D at P(3,0,0)
Should I be using Gauss's Law to solve this problem? I was considering using a spherical ...
1
vote
0answers
265 views
What is a boundary condition for capacitors/dielectrics?
I am extremely confused about what boundary conditions are. One minute ago I was solving easy capacitor questions and the next minute I am being asked boundary condition questions and there is no such ...
1
vote
2answers
90 views
Origin of field deduced from potential
Related: Tubelights+power lines pictures?
I would've edited this into the above question, but I realized that there' enough to it to qualify as a new one. Plus this seems to be a confusion of ...
0
votes
1answer
179 views
Tubelights+power lines pictures?
I've come across many pictures like these, sometimes in chain emails reporting the dangers of power lines.
Another claim is that they run on "wasted" energy.
The explanations given are that the ...
9
votes
3answers
304 views
Current in a simple circuit
I was going over my notes for an introductory course to electricity and magnetism and was intrigued by something I don't have an answer to. I remember my professor mentioning, to the best I can ...
0
votes
0answers
112 views
What is the electric field part of an EM wave? Radiation field or the induction field?
Look at this image:
I wonder if the electric field is from the induction field from a vibrating electron or the radiation field? If it is from the radiation field, as I suppose, than can someone ...
7
votes
2answers
405 views
Mechanism by which electric and magnetic fields interrelate
I read that force due to electric field on some particle in one reference frame can exhibit itself as force due to magnetic field in some other reference frame and that electric and magnetic fields ...
3
votes
1answer
917 views
Force from point charge on perfect dipole
Have a point charge and a perfect dipole $\vec{p}$ a distance $r$ away. Angle between $\vec{p}$ and $\hat{r}$ is $\theta$. Want to find force on dipole.
I'm having more than a little difficulty ...
0
votes
2answers
372 views
Help me find electric field strength vector for this given equipotential line
I'm a physics tutor. This is the question from a High school book.
The equation of an equipotential line in an electric field is y = 2x,
then the electric field strength vector at (1, 2) may be ...
3
votes
1answer
343 views
Given charge distribution find electric field
Given a charge distribution $\rho(\vec{r})$ where $\vec{r}$ is the position vector and that $\rho$ is a function of only $|x|$, Why is it that the corresponding electric field $E$ is necessarily of ...
0
votes
3answers
1k views
Electric field at a point inside a capacitor
Let's say I have a parallel plate capacitor.
How would I find the electric field at a certain point INSIDE the capacitor (inside the dielectric let's say). From what I understand, the flux of the ...
1
vote
2answers
151 views
Fields versus Photons
Does the field of a set of photons behave differently from a single photon.
e.g. Suppose I have a group of photons with their Electric fields $\mathbb{E}_n$ all aligned. So
$$\mathbb{E}_{\text{tot}} ...
2
votes
3answers
199 views
Gauss' law - changes in the magnitude of E field inside the closed surface
Gauss's law says that the flux through a closed surface which contains neither a sink nor a source will be zero.
It's quite clear that all field lines will have to exit somehow, but the
strength of ...
1
vote
1answer
144 views
Complex Potentials, Potentials and Fields
Suppose an electric field $E=-\nabla \psi$ where $\psi=-Q\ln r$ where $Q$ is just some constant and I have found its harmonic conjugate to be $-Q\theta+c$ where $c$ is some constant. What does it say ...
0
votes
2answers
656 views
How to calculate the electric field at a point in space
Let's say I have a uniformly-charged wire bent into a semi-circle around the origin. How can I find the electric field (magnitude and direction)
I'm not even sure if I should use Coulomb's or Gauss' ...
-2
votes
1answer
4k views
Electric field due to nonconducting plastic sheets [closed]
Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities $\sigma_1, \sigma_2, \sigma_3$ and $\sigma_4$ on their surfaces (the four surfaces are in the ...
1
vote
0answers
266 views
How to find the electric field at a point based on a uniformly charged surface
What is the general solution to finding the electric field at a point based on some (or multiple) charged surfaces. I know that we can perform a line/surface integral if a charge is close to a wire or ...
5
votes
3answers
211 views
Is it true that $\vec{E}\neq 0$ inside a 1- or 2-dimensional conductor?
It is known that when a conductor is placed in an electric field, the charges redistribute themselves such that $E=0$ inside the conductor. I was also told that the same is NOT true for the 2D and 1D ...
1
vote
2answers
469 views
Is there really no meaning in potential energy and potential?
I have been told all my physics life that potential energy between two mass/charge has no meaning and only their difference has meaning. The same goes for electric potential, only the difference ...
0
votes
2answers
607 views
Electric field problem
First of all I hope I'm doing the right thing by posting this message on the stack exchange site. I know you aren't my personal problem solvers, but I just can't solve it. And maybe this problem is ...
-1
votes
1answer
130 views
Law of conservation of energy at the space.? [closed]
Energy can neither be created nor be destroyed,
if energy disappear in one form it will reappear in another form without any loss.
so what will happen if FAN switched on in the space. ?
1.Electrical ...
2
votes
2answers
313 views
Gauss' law giving zero field where field is not zero?
Two plastic sheets with charged densities as shown:
I'm trying to find the field at $B$. I obtained the correct answer by adding up the fields created by each charge density. But I realized that ...
4
votes
3answers
192 views
What´s the electric field in the entire space generated by a uniform (but not constant) magnetic field?
Let me explain in details. Consider a region in space with no free charges and no free currents, so that the charge density is $\rho=0$ and the volumetric current is $\vec{J}=\vec{0} \text{ }$ in the ...
0
votes
1answer
2k views
Electric field calculator [closed]
Where can I find an electric field calculator?
I'm looking for something that can use "x" (or any varable) as a point charge.
specifically, I'm looking for something that can I can imput the field ...
6
votes
1answer
739 views
What is the penetration length of static electric field into conducting metals?
How large is the penetration length for static electric field into good conductors?
I have two versions: (1) few atomic spacings
$$a\sim n_{e}^{-1/3},$$
and (2) Debye length computed by Fermi ...
2
votes
3answers
1k views
right hand rule using left hand?
im kind of confused, the right hand rule is used to know where the direction the magnetic field created by the current is going .
is there any particular reason why the right hand is used to ...
2
votes
3answers
2k views
why do we test electric fields with positive charges? not negative ones?
Is there any difference between using a positive vs a negative charge to test an electric field? If so, please explain.
0
votes
0answers
327 views
A question related to Gauss's Law [closed]
I'm unable to solve this numerical based on Gauss's Law:
A charge Q is distributed uniformly within the material of a hollow sphere of inner and outer radii: r1 and r2. Find the electric field at a ...
3
votes
5answers
467 views
What is the origin of the Dirac delta term in the dipole electric field?
I am a bit lost how one has deduced the formula for electric field with electric dipole because of some inconsistency between different sources. The Wikipedia article contains a delta function in the ...
3
votes
1answer
172 views
Using Relaxation Method to Model Negative Dielectrics in an electric field?
How can you use the relaxation method to model negative dielectrics?
The relaxation method is usually used to model electrostatics problems but negative dielectrics are only see in dynamic systems.
...
