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 [electricity] tag, as questions about the phenomenon & theory of electricity do not necessarily involve the discussion of fields.
221 questions from the last 365 days
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Would reflections make an electromagnetic wave more penetrating into metals?
First i should clarify how i arrived at this question. I understand that in the case of an EM wave reflected off a higher refractive index surface, the reflected electric field vector changes ...
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Where is the increased mass reserved based on Einstein's mass-energy equation?
Assume a huge parallel-plate capacitor with plates located at an infinite distance away from each other. If we tend to move a positively charged object ($+q$) with a rest mass of $m$ against the ...
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What is the equation for the change in electric potential due to a field generated by a point charge? [duplicate]
I'm a current AP Physics 2 high school student with a test in a few days; a swift reply would be very much appreciated. Thank you in advance.
My question is concerning the formula for the change in ...
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How long can electrohydrodynamic (EHD) propulsion last?
In an electrohydrodynamic (EHD) propulsion, I know that there is a thin wire with high voltage (emitter) and a 0-voltage collector. Because of the radial electric field around the thin wire, electrons ...
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Rotation of electric field vector or polarization
Given a circularly polarized light field. I am using complex notation to represent the field,
$$\vec{E}(z=0, t) = \frac{1}{\sqrt2} [ \hat{x} (\cos(\omega t) - i \sin(\omega t)) + \hat{y} (i\cos(\omega ...
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How exactly do charged capacitors decrease current?
I recently learned about how capacitors function in electric circuits, and I came across an apparent contradiction that I wanted to ask about. On one hand, I know that as charge builds up on the ...
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How is the $E$ field at the surface of a charged rod affected by its dielectric constant?
I am seeking clarification on a concept from a test question I have been studying.
Essentially, the question gives an example of an infinitely long charged rod, made of an insulating material. The rod ...
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Feynman lectures, relative electric field
Both pictures are from Feynman Lectures, vol2 chapter 26, and are talking about the relative electric field.
In the first picture, equation 26.6 says that Ex(electric field in the x direction) of the ...
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Why is polarization $\mathbf{P}$ proportional to the $\mathbf{E}$ field, but magnetization $\mathbf{M}$ proportional to the $\mathbf{H}$ field?
Why is the polarization intensity $\mathbf{P}$ proportional to $\mathbf{E}$ (electronic filed), while the magnetization intensity $\mathbf{M}$ proportional to $\mathbf{H}$ (magnetic filed), when the ...
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Successive image charge method
Given 2 plates separated by the distance $d$, grounded and a point charge $Q$ between the plates from the first plate by a distance of $x$. We have to find the net charge on both the plates.
The net ...
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Griffith, Electrodynamics, 4th Edition, Example 4.8. (Second part)
P.s. This post is a continuation from Griffith, Electrodynamics, 4th Edition, Example 4.8. (First part). I am reading the Griffith, Electrodynamics book, 4th edition, Example 4.8. I want to understand ...
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Feynman's approximation of electric field far away from a moving charge
Feynman in his lectures, Vol 1, chapter 28 gives formula for electric field at point $P$ which is generated by a moving charge $q$ as
$$E = \frac{-q}{4\pi\epsilon_0}[\frac{e_{r'}}{r'^2}+\frac{r'}{c}\...
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A problem with a current-carrying sheet's magnetic field as viewed by an observer moving perpendicular to the current direction (Part II)
Although I have found an answer to my previous question, the problem is still vague for me, as we consider the viewpoint of the observer who recedes from the current-carrying sheet along the $y$-axis. ...
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A problem with a current-carrying sheet's magnetic field as viewed by an observer moving perpendicular to the current direction (Part I)
In my previous question, entitled a problem with a current-carrying wire's magnetic field as viewed by an observer moving perpendicular to it, @Dale answered that:
so indeed, as you mentioned, in ...
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Reasoning for why a conductor in an electric field reaches electrostatic equilibrium
Suppose a solid conductor is placed in an electric field. The textbooks I've consulted state that the electrons in the conductor would reach electrostatic equilibrium. From that, it is deduced that ...
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Can you levitate objects using electric fields?
Magnetic levitation uses magnetic fields to levitate objects. Could you use electric fields to levitate objects?
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Different fields produced by balls of uniform electric vs magnetic dipoles
An electric dipole and a magnetic dipole produce the same field (only difference is $1/\varepsilon_0$ vs $\mu_0$). But a solid ball with a uniform dipole density produces different fields inside the ...
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Vector forms of Coulomb's Law and an Electric Field Equation [closed]
For many days I've been wondering about this topic.
How can one express in a vector form the equations for the electric field generated by a charge and Coulomb's law?
I know that as both electric ...
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Clarification on the role of electric fields in our body
An article on Forbes, explains the role of electric fields in our body. It says(an excerpt):
"Our bodies are made up of cells, which are made up of atoms. And atoms are… well they’re mostly empty ...
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Which Electric Field an Oscillating charge produces - Coulombic,Induced,Both? What field is experienced by test charge at zero crossing of $E$ & $B$?
In my textbook (page 275):
https://blogmedia.testbook.com/blog/wp-content/uploads/2022/04/physics-part-i-chapter-8-b20d7a00.pdf
and on Wikipedia:
https://en.wikipedia.org/wiki/File:...
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Will $\nabla \times \vec{E}$ be zero for atoms moving away radially outward?
Consider neutral atoms moving radially outward in $xy$ plane from origin with constant velocity $v$ (so they are always on the boundary of a circle).
Given $$\vec{B} = B_0 \mathbf{\hat{z}}.$$
Since ...
user536052
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Could you charge a battery using with a long radio aerial?
I was remembering how as a child I powered a Crystal Radio by just running a long wire 3 or 4 times around my room architraves/cornices. And was wondering why the same principle couldn't be used to ...
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Typo in "The Quantum Theory of Optical Coherence"?
I was reading through Glauber's "The Quantum Theory of Optical Coherence" Phys. Rev. 130, 2529, (1963) and found the following expressions for the positive and negative frequency components:
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Why $\nabla \cdot E = 0$ is used in the derivation of EM wave equation if a charge is needed in the first place to generate EM Wave?
In free space, when we combine Maxwell's Equations, we get E and B waves. But those waves are not possible in entirely free space (in that case, there will be no E and B fields in the first place), ...
user536052
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Measuring electrical fields from mains - difference through near grounding conductor
I often notice that the electrical fields in my home created by mains differ in dependence how close the grounding conductor is to the measurement antenna.
I haven't managed to model this yet, so I ...
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