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.
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Electric field due a charge in the cavity of a conductor
I am new to this subject, and there's a problem that is really bugging me. If we put a charge $q$ inside a spherical cavity in a spherical conductor, even if it is off-center, the charges on the outer ...
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Can a propagating radial electric field be derived from Maxwell's equations? [closed]
Using Maxwell's equations one can derive the following inhomogeneous wave equation for the electric field $\mathbf{E}$ with sources:
$$\nabla^2 \mathbf{E} - \frac{1}{c^2} \frac{\partial^2 \mathbf{E}}{\...
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Circling Charge
Suppose an electron is moving in a circular orbit under an external magnetic field. At a point far away, on the same plane as the orbit of the electron, if you look from any direction, you see an ...
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I thought lighting always makes sounds when it strikes something, am I wrong?
I was recording a storm on video and saw a very bright flash of light right in my backyard that was not attributed to a strike. Curious about what it was, I went back and did slo-mo on it, and it was ...
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What happens to the internal zero-field points of a polygon as $𝑁 → ∞$?
Consider a regular polygon with $N$ vertices, each carrying the same charge $q$, inscribed in a circle of radius $a$. For small $N$, there are $N+1$ points inside the polygon where the electric field ...
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Does an external field affect the capacitance of a capacitor?
Suppose there is an external electric field E(external), and the strength of this field decreases from point 1 to point 2. The capacitor consists of two concentric conducting spheres with a dielectric ...
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Why do we not take into account the forces arising from electrostatic induction when calculating the potential inside a conductor sphere?
Problem. At a distance d from a point charge q, there is the center of
an uncharged conducting sphere with radius R. What is the potential of the sphere?
Solution. The potential of all points on the ...
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Does the electric field of a parallel-plate capacitor change as it accelerates?
Assume that the two plates of an infinitely large parallel-plate capacitor accelerate along the field lines simultaneously in the lab frame. (Fringing effects are excluded.) Is the uniform electric ...
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Why is the potential inside a conductor not equal to zero? [duplicate]
Problem. At a distance $d$ from a point charge $q$, there is the center of an uncharged conducting sphere with radius $R$. What is the potential of the sphere?
Solution. The potential of all points on ...
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Distribution of charges on metal plates after earthing
As I understand it, the electric potential of the earth relative to infinity (with $V(\infty) = 0$) is given by $\frac{kQ_e}{R_e}$, where $Q_e$ is earth's total charge and $R_e$ is earth's radius. But ...
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At what speed does a pulse propagate in a conducting wire?
I saw a previous post asking about how fast "electrical information" propagates, i.e. if I change something in a circuit, like capacitance, resistance, voltage, in a circuit, how fast will ...
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How electrical capacitance of just a wire differs from capacitance of a wire next to another isolated wire?
I connect one end of strands from one wire of a USB cable (another end in the air). Another wires in the cable are isolated from that one and each other and ends are in the air. I wonder how ...
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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 accumulated 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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How does field concept localize electromagnetism from Coulomb’s law? [closed]
From super position principle of electric field, the electric field at a point can be calculate by summation of fields from other charges. I do not see any different from summation of force from ...
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