Tagged Questions
-1
votes
0answers
20 views
Electric Field and Electric Potential [closed]
How can electric field and electric potential function for charged conducting and uniformly charged non-conducting spheres?
5
votes
3answers
114 views
Horizontal $E$-field for a charged conducting disk
For part of a simulation I am writing, I need to know the electric field emitted from a charged conducting disk. If the disk was laid out in the $x$-$y$ plane, I am interested in the field in that ...
0
votes
0answers
30 views
Energy content after moving point charge [closed]
I have the following exercise:
In point A there is a charge with $Q_1 = 3.3\times10^{-5} C$
In point B charge $Q_2 = 8.5\times10^{-6} C$
In point C charge $Q_3 = -6\times10^{-6} C$
This happens ...
1
vote
0answers
40 views
Static electrical attraction [closed]
Coulomb's law is used to calculate the electrical attraction between 2 charged particles, what formula do I use to calculate an electrical attraction magnitude between 2 plates? Let's assume the first ...
0
votes
1answer
33 views
Gaussian surface in a charged infinite plance sheet
The following question arises on the use of Gauss law. In the charged finite sheet problem, we consider a Gaussian surface on only one side of the sheet. But, In the case of an infinite sheet, we ...
0
votes
1answer
53 views
Electric field and potential [closed]
An oil drop of radius 0.70mm containing a charge of -4.8 x 10-19 C is placed in an electric field if the drop remain stationary at the point find the magnitude and direction of electric field ...
0
votes
1answer
228 views
Non conducting charged planes
I have two parallel non conducting charged planes with opposite charges $6\mu C/m^2$, area $A = 3m^2$ and distance between the planes $d = 0.004 m$. I know the potential between these two planes is ...
0
votes
1answer
72 views
Electric field of a negative charge
Displacing something against the gravitational field, gains it potential energy. Moving something against the nature requires work. If the electric field of a negative source charge 'Q' points inward, ...
2
votes
2answers
215 views
Electric field of a negative charge
How was it discovered that the electric field of a negative charge points towards the charge itself? Is it true?
(Courtesy of wikipedia)
0
votes
1answer
208 views
Electric field due to nonconducting sphere
For calculating electric field outside a nonconducting sphere with a hollow spherical cavity. When I use the rule (Charge density= $dQ/dV$), I don't know exactly what is $dV$, is the volume here ...
1
vote
1answer
72 views
Should the electric potential of a positively charged sphere be negative?
Because the indefinite integral of the electric field results in a negative value? (As the function is proportional to $r^{-2}$?
I've got to be missing something... Help please!! Thanks!
Also, I ...
2
votes
1answer
495 views
Gradient of the electric potential
I was wondering if for a point-like charged object, does the gradient of the electric potential point in the direction of maximum increase or maximum decrease of the function $V$?
1
vote
2answers
136 views
Electric lines of force
Why cant electric lines of force pass through the charged sphere? Well, basically that's how a Faraday cage works, but how can it be so?
2
votes
3answers
128 views
Explanation on the resulting forces of two positive point charges
Why will the resulting force lines of two positive point charges be like this:
I would expect this:
1
vote
3answers
194 views
Why can we use Gauss' law to compute electric field?
For simplicity I'm considering only the sphere case.
In the Gauss' Law formulation we have some field E introduced by charges $Q$ inside some sphere, then we compute flux and integrate, and we get ...
0
votes
0answers
65 views
Electric field singularity
What's a general proof for the log-singularity of electric field near the edge of a uniformly charged surface?
2
votes
2answers
138 views
Electric field lines
If electric field lines cannot terminate in empty space, in the simple example of two equal charges what happens to the line starting from one of the charges toward the other in the middle?
0
votes
1answer
144 views
Finding the electric field
The charge per unit length on a long, straight filament is -91.9 µC/m.
(a) Find the electric field 10.0 cm from the filament, where distances are measured perpendicular to the length of the ...
2
votes
1answer
151 views
Minimizing potential energy of a dipole in an electric field
My test paper asked me which way a dipole should be orientated in an electric field to minimize its potential energy. My answer was that the dipole should lie parallel to the electric field with the ...
0
votes
1answer
192 views
Electric Fields
The problem I am working on is, "In the figure below, determine the point (other than infinity) at which the electric field is zero. (Let $q_1 = -2.45\ \mu C$ and $q_2 = 6.5\ \mu C$)
Here is a little ...
3
votes
1answer
369 views
Electric Field due to a charged sphere
Suppose we have a spherical surface with a surface charge density varying as $cos(\theta)$. Apparently one can find the electric field both outside and inside such a spherical surface by superposing ...
3
votes
1answer
165 views
Revealing Electric field lines through Grass seeds in mineral oil
In one of Walter Lewin's famous lectures, he takes a small container almost completely filled with mineral oil and grass seeds (I'll keep looking for the video to link to it). He connects two ...
0
votes
1answer
277 views
Electric field and insulator or dielectric
I have a uniform electric field $E$ projected from left to right and I placed an insulator or dielectric right in the middle of it. To the left of the insulator, the $E$ is the original $E$. Inside ...
1
vote
2answers
209 views
Change in intensity of electric field with constant velocity
Consider a +Q charged particle is travelling towards another test charge +Q. Now what would be the difference in electric field experienced by the test charge(avoid the gradual decrease in distance ...
0
votes
3answers
265 views
Is there is any difference between Electric Flux ($\Psi$) and Total number of Electric Field lines ($E\times$Area)?
Is there is any difference between Electric Flux ($\Psi$) and Total number of Electric Field lines ($E\times$Area)?
$\psi = \Sigma Q$, and $\phi$ = Electric field intensity $\times$ Area
where Area ...
0
votes
0answers
34 views
Working out the electron mobility from the transfer rate (1/s)
I have an electric field value for a uniform structure through which an electron travels. Given that I've calculated a transfer rate (frequency) for the electron when it goes from one molecule to the ...
1
vote
1answer
418 views
Electric field inside and outside a metallic hollow sphere
1) It is known that inside a metallic hollow sphere it will not experience outside electric field because of the charge separation of electrons and holes at the surface of sphere and creating an equal ...
2
votes
1answer
90 views
Working out the electric field from applied energy
I have created a simulation of one electron bouncing through a 3D mesh of molecules. The electron hopping is determined by a calculation of electron transfer rate using the Marcus equation (a result ...
1
vote
1answer
291 views
Finding the electric field for a shell of charge
Suppose we have charge density defined
$$
\rho(x,y,z) =
\begin{cases}
0 & 0 \leq r < a \\
K & a \leq r\leq b\\
0 & b< r
\end{cases}
$$
For some constants $K,a,b$
How would ...
0
votes
1answer
171 views
1
vote
1answer
426 views
The formula of the force exerted on an electric dipole by non-uniform electric field
When an electric dipole of moment $\mathbf{P}$ is located in a non-uniform electric field $\mathbf{E}$, there is an net force exerted on it.
However, the formula of the force in some books is read ...
0
votes
2answers
1k views
Why is electric field zero inside a hollow metal sphere ?
The figure below shows a hollow metal sphere with a positive point charge $Q$ sitting outside it. What is the electric field at the center of sphere ? The answer is zero (look at here at the beginning ...
1
vote
2answers
348 views
electric potential at center of uniform electric field
it is said that the electric potential at the center of uniform electric field is zero.
my question is that why is it zero?
electric potential is the work done per unit charge.
$V = W/q$
and this ...
0
votes
1answer
108 views
Will the plates of a parallel plates capacitor keep its charge after being charged then seperated from the non- conductor?
If i had 3 plates 2 metals and 1 glass .I put them together to form a basic parallel plates capacitor.
After charging it and approaching it to an electroscope nothing happened that's because ...
1
vote
1answer
758 views
Potential Gradient & Electric field…
Potential gradient is the negative of the electric field. Does the negative (here) means that its direction is opposite to electric field.?
If it does mean this, How is the direction of the ...
3
votes
2answers
206 views
Electrostatic notion of voltage as it applies to circuits
I have a question that's been bothering me about electric fields, voltage, and circuit analysis.
Initially, I came to understand voltage as it was taught in the context of electrostatics - through ...
5
votes
5answers
447 views
Paradox with Gauss' law when space is uniformly charged everywhere
Consider that space is uniformly charged everywhere, i.e., filled with a uniform charge distribution, $\rho$, everywhere.
By symmetry, the electric field is zero everywhere. (If I take any point in ...
2
votes
2answers
147 views
Energy in electric field
I'm having some trouble understanding a homework question and would appreciate some help.
The question is as follows:
Jenny charges a capacitor with the help of a battery. She then removes
the ...
4
votes
3answers
470 views
Field due to current in a wire
Suppose a current flows in a straight cylindrical wire so that an electric field $\textbf{E}$ is maintained in the wire.
Will there be an electric field just outside the wire..?
1
vote
1answer
162 views
What is discontinuity in Vector Fields
I am reading David J. Griffiths and have a problem understanding the concept of discontinuity for E-field.
The E-field has apparently to components. (How does he decompose the vector field into the ...
1
vote
2answers
162 views
In which cases is it better to use Gauss' law?
I could, for example calculate the electric field near a charged rod of infinite length using the classic definition of the electric field, and integrating the: $$
\overrightarrow{dE} = \frac{dq}{4 ...
2
votes
2answers
561 views
Electric potential of sphere
(a) I am a little confused about this part. The point at A to B isn't radial. The electric field is radially outward, but if I look at the integral
$$\int_{a}^{b}\mathbf{E}\cdot d\mathbf{s} = ...
0
votes
1answer
95 views
Why does a point charge generate an electric field and why is an electric field represented by this formula?
Why does a point charge generate an electric field and why is an electric field represented by this formula
$$E ~=~ \frac{q}{4 \pi \epsilon r^2},$$
where $\epsilon$ is permittivity of free space ...
1
vote
4answers
299 views
Why does it seem that the potential difference dependence of capacitance and total energy stored in a parallel-plate capacitor are contradictory?
Consider a parallel-plate capacitor. Charge is stored physically on electrodes ("plates") which are flat and parallel to one another. If one electrode has charge $+Q$ and the other electrode has ...
2
votes
3answers
2k views
How does electricity flow in conductor when potential difference is applied?
Electrons move from higher potential to lower potential. When a conductor is connected to battery, electron move from negative terminal to positive terminal.
But the battery itself forms a Electric ...
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 ...
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
296 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 ...
