# Questions tagged [capacitance]

The ability of an object to store electric charge.

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### Express Laplace transform of voltage across a capacitor in terms of charge

In Charge Tunneling Rates in Ultrasmall Junctions section 2.1, the authors consider the problem of charge relaxation in a simple circuit shown in Figure A. The implicitly use an assumption made about ...
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### What is capacitance, in general?

In circuit analysis software capacitance can be measured between any two nodes of a circuit or of a multiterminal device. In practical terms we take $C_{ij}$, the capacitance between $i$ and $j$ as ...
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### Is the charge on the plates of a parallel plate capacitor induced charge?

My question is- Is the charge on the plates of a parallel plate capacitor induced charge? Imagine two plates of the capacitor have $+q$ and $-q$ charges on it. Basically, what I want to know is ...
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### Confusion regarding Gauss law and capacitors

In book (Halliday Resnick Krane, 2nd Part, fifth edition), it's written that when you you put some charge in an isolated conductor, then within around $10^{-9}$ seconds the charges all go to the ...
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### non-symmetric spherical capacitor

The figures below illustrate (in cross-sectional view) three separate spherical capacitors: an inner solid conducting sphere is surrounded by a hollow thin conducting shell, concentric with the sphere....
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### Two balls are attached with a very long and thin conducting wire to two conducting plates. How does the capacitor react in this situation?

The question is as follows (taken from a previous exam): Two balls (conductors w/ Radius $R_1$ for left ball ball, $R_2$ for right) are attached with a very long and thin conducting wire to two ...
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### Charge on the plate of the capacitor

I was reading parallel plate capacitors in my book today and there I saw that the battery provides +Q charge to positive plate and -Q charge to negative plate? But we know that only electrons can flow ...
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### How does humidity affect the dielectric constant of a material?

I'm trying to figure out how a humidity sensor using a Capacitor works, and every document I have managed to find seems to come to the conclusion that an increase in humidity causes the capacitance to ...
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### In an $RC$ Circuit, when polarity of a battery is reversed, how much energy is dissipated into heat?

https://ibb.co/tPL02dZ In the figure, a $20 nF$ capacitor is connected in parallel across a $30 nF$ capacitor. There are $2$ resistors of $10 Ī©$ connected in series with the capacitors. A ...
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### How Are Electromagnetic Waves Produced?

How EM waves are produced say by a capacitor of an LC circuit here if $E$ is increasing in upward direction? My thoughts Thought 1:- If E is increasing E flux is increasing thus B field must be ...
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### Common potential in Capacitors

If two isolated charged capacitors (of different capacitance) are connected in parallel to each other they acquire a common potential. But suppose if i connect positive plate of one capacitor to ...
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### Is it possible to use a capacitor to cool the surrounding medium by pulling its plates apart while remaining connected to the battery?

Considering a parallel plate capacitor connected to a battery. If plates are pulled apart heat is not produced. But the battery is absorbing energy as it gets charged. So heat is absorbed. If this is ...
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### Dual finite parallel disk capacitor; estimating mathematically that the potential or field or distribution is nearly uniform from first principles

Working through Purcell. In particular, doing my best to put everything on a firm footing, mathematically, so that I can understand it. But, I have struggled all week in establishing from first ...
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### In series RLC circuit, does decreasing the capacitance value really make the circuit more capacitive circuit?

This seems very counter intuitive to me. How can decreasing the capacitance value make the circuit more capacitive ? The math tells me so : If $C$ decreases then $X_c = \dfrac{1}{\omega C}$ ...
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### What is Capacitance for a Spherical Shell pair?

Consider three Scenarios : 1) In this case , we are Calculating $$\frac{d(Q_b)}{d( \triangle Vab)}$$ 2) In this case , we are Calculating $$\frac{d(Q_a)}{d( \triangle Vab)}$$ 3) In this ...
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Given a parallel plate capacitor of width $w$, length $l$, with a dielectric moving along the length $l$. Let the dielectric be from $x$ onwards. The capacitance will be $\frac{w \epsilon_0}{d} (\... 1answer 132 views ### Effect of Motion on Capacitors What will happen if a capacitor is accelerated or rotated very very fast? Will its capacitance decrease? Will one of the plates be able to hold the electrons which is providing the Potential ... 0answers 17 views ### Need help understanding a statement about energy in capacitors The electric potential energy stored in a charged capacitor is just equal to the amount of work required to charge itāthat is, to separate opposite charges and place them on ... 1answer 32 views ### Maximum charge of a separate capacitor plate Suppose we have an initially charged parallel plate capacitor, then we separate the plates so each plate has a positive and negative charge (I did an experiment, the plates hold the charge), I think ... 0answers 27 views ### Leyden jar-How does the storing process work? We can view the Leyden jar as a capacitor and a dielectric (glass). When the metal parts are charged thus is due to influence in the dielectric a counter electric field to be found.When we separate ... 0answers 21 views ### Charge density inside dielectric with conductivity Consider the figures I and II , they consist of similar circuits with identical batteries. There are two different slabs connected in the circuit, both are geometrically identical and have the same ... 1answer 33 views ### How does RF communication between electronic circuit elements affect the circuit? The other day, a friend and I were looking at a simple resistor-capacitor-inductor circuit. As we were looking at the circuit, he mentioned that the capacitors and inductors "talked" to each ... 1answer 36 views ### Is it necessary that a capacitor stores charge? Is it necessary that a capacitor storage charge? I am a little bit confused. For example: if I take two concentric conducting shells and a positive point charge at the centre. Both the surfaces (outer ... 0answers 39 views ### Crossover filter gives weird results I was analyzing results of an experiment on a crossover filter and I was trying to take into consideration the parasitic resistance of the inductor L (called$R_L$). I know the theoretical crossover ... 0answers 24 views ### Why does single electron Coulomb blockade charging use$Q^2/2C$? Classically stored energy of a capacitor is$\frac{Q^2}{2C}$. However, the difference in energy when a single electron travels across the gates should be$qV$But in couloumb blockade calculations, ... 1answer 234 views ### Capacitance of spherical capacitor when inner surface of outer sphere is earthed Let there be two concentric shells in which the outer sphere contains charge Q1 and inner sphere contains charge Q.Capacitance of spherical capacitor when the inner surface of the outer sphere is ... 1answer 56 views ### Why is the field inside a capacitor not the sum of the field produced by each plate? In this answer by David Z, we can read, When discussing an ideal parallel-plate capacitor,$\sigma$usually denotes the area charge density of the plate as a whole - that is, the total charge on the ... 2answers 58 views ### Attenuation of a signal Suppose that I have a wire between two terminals and I want to send a high frequency ($f$) signal from one to another. Is the inductance and capacitance per unit of distance enough to calculate the ... 0answers 39 views ### The force needed to move air for electrostatic speakers/headphones I am trying to determine what force is needed for the membrane of an electrostatic speaker (headphones, etc) to move the air at a particular frequency. I know that the formula for the force acting on ... 0answers 10 views ### Inner Sphere of Capacitor is Grounded versus Rested on Insulated Stand My Question is about understanding the difference in Charge Distribution in a Spherical Capacitor in 2 Scenarios Here are the details of the Problem scenarios :- If we have a Spherical Capacitor ... 0answers 24 views ### Charge distribution and potential changes on earthing for conductors placed close to each other? Suppose we have two conducting plates with charges$2Q$and$3Q$placed close to each other (ignore edge effects for simplicity). It is clear that when the switch is open, the charge distribution is ... 1answer 55 views ### Capacitor problem: What's wrong with this? The capacitor shown contains 3 different dielectric material$\epsilon_1,\epsilon_2,\epsilon_3$between the top and bottom metallic plates on which lie teh points$A$and$B$as shown. The electric ... 0answers 27 views ### A relationship between parallel plate capcatior's capacitance & it's spacing distance In my experiment class, I measured a curve between the parallel plate capacitor's capacitance and it's spacing distance. But the result is not very similar to expectation - despite the spacing ... 1answer 206 views ### Repulsive force from charge accumulation in a capacitor plate? During a charged state of a capacitor (Regardless of the type of capacitor), Simple parallel plate: .png Parallel plate with dielectric material in the gap: ]3 Supercapacitor: How is the ... 0answers 73 views ### Calculating the self capacitance of a rectangular electrode with a dielectric on one side I am trying to derive an expression for the capacitance of a rectangular electrode with a dielectric material of thickness$t$and relative permittivity$\epsilon_r$in contact with one side, sized ... 0answers 16 views ### Effects generated from a supercapacitor placed in a time varying external magnetic field? The diagram above, showcases the simple outlook of a supercapacitor's interior and combining it with a full circuit loop. If an exterior magnetic field is introduced in all the operating states of a ... 0answers 24 views ### Metal Oxide Semiconductor (MOS) Capacitor strong inversion Why the electron bands in the Body of the MOS capacitor do not bend much futher after the threshold voltage is applied? What stops them from doing it? For reference Modern Semiconductor Devices for IC ... 0answers 144 views ### How does charge flow (directions) from capacitors in this question? A circuit is connected as shown in the figure with the switch S open. When the switch is closed the total amount of charge that flows from$Y$to$X$is? (A)$0$(B) 54$\mu$C (C) 27$\mu$C (D) 81$...
Suppose I have a capacitor with a dielectric between its plates. Intially the temperature of dielectric is $T_{-1}$. The capacitor is fully charged and the temperature of dielectric is noted.. say, \$...