All Questions
22 questions
3
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1
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57
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Energy in Dielectric Medium as a Sea of Dipoles
Simply, why is the energy density in a dielectric medium = $\frac{1}{2}K\epsilon_oE^2$ where K is the dielectric constant of the dielectric medium?
Working proof
Consider a capacitor that is charged ...
- 45
0
votes
2
answers
38
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For a plane isolated capacitor with a dielectric slab partially introduced inside it, what's indpendent of the medium? $\mathbf E$ or $\mathbf D$?
Say we have an isolated capacitor with charge $Q$ and a dielectric slab, $\varepsilon_r$, partially introduced between the capacitor's plates, then, I'd say the displacement vector should be the same ...
- 420
1
vote
1
answer
30
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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 ...
- 49
1
vote
1
answer
92
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Does the current inside a capacitor with dielectric becomes zero, if a DC (constant)voltage is applied?
Imagine a capacitor with dielectric with conductivity $\sigma$ and constant voltage source with voltage applied say $V$ is applied to it's ends, now using Ohm's Law we have $ \vec{J} = \sigma \vec{E}$....
0
votes
1
answer
27
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Finding potential difference for one side of a parallel plate capacitor with dielectrics in parallel [duplicate]
I'm doing some homework problems and there's a question that asks for the potential difference of the left side of a parallel plate capacitor that looks like this:
...
- 1
0
votes
1
answer
167
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Is an electrical capacitor ever possible to exist in a perfect vacuum space?
Fig.1 Magnetic field outside the plates of a charging capacitor
This question could be rephrased as:
Does a non-ideal capacitor have a magnetic field outside its plates after it is fully charged?
It ...
- 4,376
1
vote
2
answers
116
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For capacitors, why does the dielectric need to be inserted at a small constant speed?
Likely a very silly question.
I am aware that there is an attractive force from a charged parallel-plate capacitor in an open circuit without battery pulling the dielectric in, and that a decrease in ...
- 13
0
votes
2
answers
1k
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Surface charge on dielectric interface
What I have in mind is a system that consists of a capacitor filled with two dielectric materials, one of them with dielectric constant $\kappa_1$ and the other with $\kappa_2$. The capacitor is ...
- 12.1k
0
votes
1
answer
227
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Does the dielectric constant changes as the voltage is applied in every dielectric material?
As the voltage is applied at both sides of the dielectric material(ex. front surface +5V and rear surface 0V), the energy is stored in the material, right?
I heard it's because the dielectric ...
0
votes
1
answer
167
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$E$-field between dielectric and plate in parallel plate capacitor and Feynman's claim
Feynman says about $E_{0}$ below
Note that the field $E_{0}$ between the metal plate and the surface of the dielectric is higher than the field $E$; it corresponds to $\sigma _{free}$ alone.
$\...
- 1,292
0
votes
0
answers
553
views
Fringe fields do not explain the origin of the force pushing dielectric slab inside a capacitor?
In the problem of a dielectric slab being inserted between the plates of a parallel plate capacitor, it is usually argued that the origin of the inward force acting on the slab is the fringing ...
- 50
0
votes
2
answers
1k
views
Effects of Dielectric on the Electrostatic Potential Inside a Capacitor
Let's consider two identical capacitors (same geometry) with the same applied DC voltage, but with different dielectrics.
Is the electrostatic potential function V (y) (with y = distance with ...
- 1,329
1
vote
2
answers
556
views
Force on dielectric on pulling it out from capacitor
This is the text from Griffiths Electrodynamics for calculating force on dielectric on pulling it out from capacitor when the capacitor is connected to Battery so that voltage of capacitor is fixed:
...
- 129
0
votes
1
answer
408
views
Is it possible to create and control a magnetic field in a dielectric material?
A capacitor is usually formed by an insulater between two conductive plates. By applying voltage difference between the plates we create an electric field within the insulator in one direction. If you ...
- 175
0
votes
2
answers
228
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What happens to a system of capacitors when a dielectric is inserted into one of them?
sorry for my English.
While doing some homework I've stumbled upon this "circuit":
the system is connected to the same potential difference through a generator that is connected to points A ...
- 55
1
vote
0
answers
24
views
Is the permittivity of a dielectric medium measured by application of radio frequency of 1 KHz and a resonant circuit of 1KHz are same?
I am working on a procedure in which I assess the dielectric constant of a medium by subjecting the dielectric medium to electromagnetic radiation of certain frequency (or the medium is subjected to a ...
- 75
-1
votes
1
answer
924
views
dielectric slab inserted into constant charge capacitor
I derived the equation for the force $F$ acting on a dielectric of dielectric constant $K$ being inserted into a constant voltage (connected to battery) parallel plate capacitor of capacity $C$, ...
- 21
0
votes
1
answer
113
views
Calculating electric field in a dielectric
Why the electric field calculated in a dielectric is equal to the uniform charge density per unit area divided by epsilon-0 (which is the permitivity in space) shouldn't it be divided by another ...
- 756
0
votes
1
answer
5k
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Force per unit length between two long parallel wires, one of which is insulated
Suppose we have two very long parallel wires of radius $a$ and distance between their axes $d$ ($d>>a$). The first wire if is carrying charge of linear charge density $\alpha$ and is insulated ...
user16688
2
votes
1
answer
643
views
A dielectric table is being inserted between a plate capacitor and $\triangle U<0$ how to deduce the table is attracted to the plates?
I am practicing for an exam in my Physics $2$ course.
One of a previews exam questions described a plate capacitor and asked
to calculate the initial energy $U_{0}$, then a dielectric table
was ...
- 525
1
vote
1
answer
635
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Dielectric modification of electrostatic equations?
I have learnt that in cases of electrostatic fields inside a dielectric of any source charge, the field is reduced by a factor of K( if K, the dielectric "constant", is taken everywhere to be same). ...
- 3,168
1
vote
1
answer
3k
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Energy Change in a Capacitor by Inserting Dielectric
This is a practice Physics Subject GRE problem.
A parallel-plate capacitor has plate separation $d$. The space between the plates is empty. A battery supplying voltage $V_0$ is connected across ...
- 5,452