The electric-field tag has no wiki summary.
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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 ...
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368 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 ...
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2answers
416 views
How does the voltage between two charged sheets change if change their distance
Suppose I have two charged capacitor plates that both are isolated and carry a charge density $D = \frac QA$. According to textbook physics the electric field between them is given by $E=\frac D ...
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293 views
Electric force in DNA molecule
Given that distance between O-H and N-H bonds are 0.11 nm and
How do I compute the net force exerted from Thymine and Adenine? A hint given is:
Hint: To keep calculations fairly simple, yet ...
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1answer
162 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 ...
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267 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 ...
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6answers
204 views
Relation between field strength and potential?
In terms of gravity and electric fields, I'm not sure what the difference is between field strength and potential is and how they are related? Both using maths and not.
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2answers
103 views
The direction of electric field in a diode
Why electric field pointing to left? (The middle area is depletion region.)
(This is without any external electrical voltage applied.)
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374 views
How to draw electric fields correctly?
Draw a negatively charged plate A and a positively charged plate B with an equal charge. Draw the field. (the image is the given answer)
I however do not understand why this is. Is there any reason ...
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2answers
77 views
What forces affect point charges?
I am working on a point charge simulator, and I was wondering what forces can affect point charges (assuming that they operate in a closed system, with no externally generated light, and initial ...
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2answers
206 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 ...
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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 ...
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1answer
196 views
Intuition behind Fourier transformed spaces
Intuitively I've been able to understand a Fourier transform a change-of-basis formula - you're basically moving from position to momentum basis or from time to frequency - but what does it mean that ...
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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 ...
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2answers
67 views
Production of electricity from atmosphere
I read the electric field intesity at the surface of earth is 100v/m. Then why can't we keep two metallic sheets at different heights and produce a continuous current by connecting these two sheets ...
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1answer
415 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 ...
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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 ...
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1answer
290 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 ...
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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 ...
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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 ...
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2answers
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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 ...
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2answers
148 views
Energy stored in space/frequency electric field
I've come across a problem with finding the energy stored in time/frequency electric field. In space/time we have (taking $\epsilon = 1$)
$$ Energy = \frac{1}{2} \int_V |\mathbf{E}(\mathbf{x},t)|^2 ...
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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 ...
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1answer
978 views
Electric field due to a solid sphere of charge
I have been trying to understand the last step of this derivation. Consider a sphere made up of charge $+q$. Let $R$ be the radius of the sphere and $O$, its center.
A point $P$ lies inside the ...
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1answer
321 views
Divergence of non conservative electric field
I'm looking for the proof that the 1st Maxwell equation is valid also on non conservative electric field.
When we are talking about a electrostatic field, the equation is ok. We can apply the Gauss ...
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3answers
209 views
Compute closed line integral of electric field in circuit
I have a circuit where resistor is parallel to capacitor, which is charged with voltage U. How to compute line integral around closed loop to get the result of Kirchhof second law - ...
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1answer
747 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 ...
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2answers
203 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 ...
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1answer
115 views
EM force, blocking force carrier photons in a static electric field
I am doing some personal research in this specific area and wanted to ask something related to photons and EM force. are involved. Here is a thought experiment that doesn't add up to observed results, ...
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5answers
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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 ...
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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 ...
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3answers
465 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..?
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2answers
788 views
Where does the equation $E_q = \frac{kq}{r^2}$ come from in this problem?
A point charge is placed at each corner of a square with side length
$a$. The charges all have the same magnitude $q$. Two of the charges
are positive and two are negative, as shown in the ...
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4answers
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Are the field lines the same as the trajectories of a particle with initial velocity zero
Is it true that the field lines of an electric field are identical to the trajectories of a charged particle with initial velocity zero? If so, how can one prove it?
The claim is from a german ...
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Ewings Molecular Theory of Magnetism & Induction Cookers
This question regards Ewings molecular theory of magnetism
I.) Ewing's molecular theory of magnetism describes every magnetic substance as being a collection of dipoles that are initially in a state ...
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2answers
257 views
How can a non-conservative field be a scalar multiple of a conservative field?
Okay so I was reading this from University Physics by Freeman and Young and on the topic of inductors as circuit element, they wrote that $\mathbf{E_c} + \mathbf{E_n} = 0$ which makes no sense to me
...
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1answer
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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 ...
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2answers
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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 ...
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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
$$\int_{a}^{b}\mathbf{E}\cdot d\mathbf{s} = ...
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1answer
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why is total electron energy of an electron in metal negative?
In my textbook, it says that any electron bound in metals, modelled as some potential well $U$, has negative total electron energy, as shown below in the figure.
Why is the total electron energy ...
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Why does a point charge generate an electric field and why is an electric field represented by this formula?
Why does a point charge generate an electric field and why is an electric field represented by this formula
$$E ~=~ \frac{q}{4 \pi \epsilon r^2},$$
where $\epsilon$ is permittivity of free space ...
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4answers
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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 ...
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3answers
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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 ...
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How can find the electric field at the center of a semicircle (insulation material)? [closed]
I have a thin wand of insulating material. The wand is bent so as to form a semicircle of radius $R=20 cm$. The wand is a uniformly distributed charge $q= 5\ 10^{-9} C$. Calculate the electric field ...
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1answer
253 views
Improvement Of Soft Iron And Steel As Magnets
I am given to know that soft iron is used as temporary electromagnet since it has high permeability i.e. the ability to align its domains corresponding to the electric field around it, however has a ...
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2answers
335 views
Is the electric field zero inside an ideal conductor carrying a current?
By an ideal conductor, I mean one with zero resistance. Inside an ideal conductor with no current, the electric field is zero, but is the electric field still zero with the ideal conductor carrying a ...
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2answers
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Using Gauss's Law to calculate electric fields between plates
I have two earthed metal plates, separated by a distance $d$ with a plane of charge density $\sigma$ placed a distance $a$ from the lower plate. I want to derive expressions for the strength of the ...
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Can lightning be used to solve NP-complete problems?
I'm a MS/BS computer science guy who is wondering about why lightning can't (or can?) be used to solve NP complete problems efficiently, but I don't understand the physics behind lightning, so I'm ...
