All Questions
Tagged with capacitance maxwell-equations
15
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Maxwell stress tensor on a capacitor late given a dielectric
Given a capacitor with large plates (area $A$) separated by a dielectric with relative permittivity $\varepsilon_r$ and thickness $g$, I believe the Maxwell stress tensor states that the force on each ...
1
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1
answer
779
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Trying to understand how to apply Maxwell stress tensor to calculate forces
I'm struggling to understand how to use Maxwell's stress tensor to compute electromagnetic forces acting on surfaces. I'll take problem 8.7 from Griffths Introduction to Electrodynamics as an example.
...
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1
answer
342
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Doubt regarding a possible mistake in Griffiths Electrodynamics
Griffiths, in section 7.3 Maxwell's Equations, says:
There’s another way to see that Ampère’s law is bound to fail for nonsteady
currents. Suppose we’re in the process of charging up a capacitor (Fig....
- 702
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1
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Charging capacitor moving with respect to the dielectric
Suppose I am charging a capacitor, so that a magnetic field is generated. This capacitor is placed inside a dielectric material with permittivity $\epsilon$ and then it is moved parallel to it's ...
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2
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Area of reference to find magnetic field inside a (dis)charging capacitor
Faraday's law of induction can be expanded:$$V=-N\frac{d(BA)}{dt}$$ and for a circuit which creates an area between the wires if that area doesn't change then it becomes $$V=-N\frac{dB}{dt}A$$ The ...
- 425
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306
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Conversion of Maxwell's Equations to Ohm's Law
I am working on electric currents in Comsol and have the following set of simplified equations:
$$ \nabla \cdot \mathbf{J} = Q_{j,v} \\ \mathbf{E} = -\nabla V \\ \mathbf{J} = \sigma \mathbf{E} + \frac{...
- 861
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1
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669
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Changing Electric Field in a Capacitor
A capacitor has circular plates with radius $R$ and is being charged by a constant current $I$. The electric field $E$ between the plates is increasing, so the energy density is also increasing. This ...
1
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1
answer
590
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Full capacitance matrix symmetry property - how to derive it?
In this excellent article, the author, in sec. 1.4 describes the full capacitance matrix properties.
He writes:
The capacitance matrix is symmetric: $C_{ij} = C_{ji}$. This is related to the fact ...
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7
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How do capacitor plates maintain equal but opposite charges in a circuit?
I have a question regarding capacitors and their charge neutrality. When capacitors are used in circuits, the assumption is often made that the plates of the capacitors have equal and opposite charges....
- 954
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1
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119
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How does charge movement vary between insulators and conductors?
I've been reading A Student's Guide to Maxwell's Equations by Daniel Fleisch, and he states:
in nonconducting materials (called "insulators" or "dielectrics"), charge does not move freely, but may ...
user231751
3
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1
answer
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Magnetic field in a capacitor
If in a flat capacitor, formed by two circular armatures of radius $R$, placed at a distance $d$, where $R$ and $d$ are expressed in metres (m), a variable potential difference is applied to the ...
- 2,547
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Safety in ultracapacitor discharge regarding possible effects of induced voltages
Problem
I am trying to analyze the safety of two experiments involving ultracapacitor short-circuit discharges.
In the first experiment one has a discharge of a $0.45 \,\mathrm{F}$ capacitor with ...
- 1,692
1
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2
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805
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How do charges accumulate even though current flows through a capacitor?
I don't understand why do charge accumulate on each plate of capacitor.I learned about displacement current which flows through the gap of the capacitor and this makes the circuit continuous.But why ...
- 494
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1
answer
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Application of Displacement Current
I'm reasonably happy with the derivation and results of displacement current, however, I'd like to be aware of a few practical applications of this idea.
So far, the only one I'm aware of is when ...
- 432
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4
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Does displacement current exist after the capacitor gets fully charged?
The displacement current is due to changing electric field. Since, after the capacitor gets fully charged there is no changing electric field there is no displacement current.(capacitor connected to a ...
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