Questions tagged [capacitance]

The ability of an object to store electric charge.

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Maximum Impedance for LCR series circuit

Impedance of an LCR series circuit can be maximum when either Inductive Reactance or Capacitive Reactance is maximum at an instant of time. Max Capacitive Reactance is at minimum frequency, and max ...
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Entropy of dielectric in Capacitor?

So I am learning about dielectrics, and my professor was saying that if we connect capacitor containing dielectric to a DC source, theoretically it should produce little to no heat (the only heat ...
Kshitij Kumar's user avatar
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Why is potential continuous at dielectric conjunction?

Lets take for an example, a spherical capacitor with two dielectrics. The Electric Field will then be given by $$\frac{Q}{4\pi\varepsilon_0\varepsilon_r r^{2}}$$ We know that then the electric field ...
MJSTX 's user avatar
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Why does the capacitance of a capacitor depend on charge and potential?

The formula of capacitance is $$C = \frac{Q}{V}.$$ So the capacitance of a capacitor should depend on the charge and potential but it doesn't. Why?
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Why do the electric field vector and displacement vector have opposite directions for a capacitor?

I understand that the electric field vector points from positive to negative because obviously that's the basic principal I've used with many problems so far. But why does the electric field go from ...
petit beauté's user avatar
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What is the voltage across the capacitor and the charge it stores

Assume the switch has been on for a long time. Is it always the case that the voltage across the capacitor = the voltage of the battery? Even though they're in parallel.
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Doubt regarding net capacitance of a 2 hollow spheres system [closed]

Suppose we have a small neutral spherical shell of radius, say $a$. Now we place this sphere concentrically inside another spherical shell whose radius is $b$ ($a<b$). This large shell is ...
Cll Qq's user avatar
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What is the capacitance of the system of two different charged particles? [closed]

If we assume they are small spheres and their radius is very small compared to distance between them
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Why doesn't current flow stop in LC oscillation?

Why doesn't current flow stop in a LC circuit? It is supposed to stop when the magnitude of emf developed across capacitor is the same as the inductor, right?
Krishnaprasad R's user avatar
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Capacitance between conducting plane and a circle on this plane

Imagine I have a very thin conducting plane. On this plane, I carve out some of the conducting material, on a circle with radius $R$ and width $r$. I am wondering if there is an analytical formula for ...
Nicolas Schmid's user avatar
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Why doesn't charge flow from a charged capacitor to an uncharged one when the circuit is open?

Consider the following setup: Let $AB$ and $CD$ be identical capacitors with capacitance $C'$. Before switch S is closed, the energy of the system is $E = \frac{Q^2}{2C'}$. Now, when switch $S$ is ...
failedCaptcha's user avatar
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How does the presence of a static electric field affect the normal operation of an antenna (if at all)?

For arguments sake lets say I have a receiving antenna that has been positioned between two large conductive plates. Are there any differences in how that antenna operates (gain, efficiency etc.) when ...
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Current and infinite coils/resisotrs/capacitors [closed]

I have come across a lot of problems that revolve around finding equivalent resistance/capacity/inductivity. But, I can never learn the "tricks" for solving that kind of question. I just can'...
honkkingflower1234's user avatar
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Ion-Ion Scale Capacitance

Ions have three dimensions in solution and can be estimated as spheres. If ions have dimensions they can experience some degree of capacitance, e.g. an electrostatic potential which increases linearly ...
Cyclohex's user avatar
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Capacitor discharging connected to power supply AND resistor together

Lets say I have 2 capacitors P and Q connected to a 9V supply. Across P there's a resistor connected in parallel with the switch open (off position). When I turn on the battery they both fully charge. ...
Safa yousif's user avatar
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Capacitor charging a battery [closed]

I can't comment to ask for circuit clarification on some of the other questions addressing this, insufficient reputation, so I am asking as a new question. Looking at answers to the other questions a ...
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Understanding Gauss' Law on Charged Sheets and Oppositely Charged Plates

I'm grappling with understanding Gauss' Law as applied to charged sheets and oppositely charged plates. From what I've gathered, when using a Gaussian pillbox encompassing both sides of an infinite ...
Tom Cajot's user avatar
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Electric fields around plates of charge vs sheets of charge, and then made into a capacitor

I've read over several other discussions on the topic of "electric field of a sheet of charge vs electric field of a charged plate", on this very site, but I still haven't gotten the answer ...
Brian Ellis's user avatar
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Why is the electric field strength ($V/d$) constant in a charging capacitor?

The electric field strength at a point in a charging capacitor $=V/d$, and is the force that a charge would experience at a point. This doesn't seem to make sense, as all the capacitor is is 2 plates,...
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Telegraphers' equations for lossy transmission line when $R$, $L$, $G$, and $C$ are frequency dependent

The telegraphers' equations are commonly written as $$\frac{{\partial v(z,t)}}{{\partial z}} + R\space i(z,t) + L\frac{{\partial i(z,t)}}{{\partial t}} = 0$$ $$\frac{{\partial i(z,t)}}{{\partial z}} + ...
Andy Ackland's user avatar
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How does this circuit behave?

A,B are connected to a battery with $V$ voltage. When $S$ is open we can just calcualte the total capacitance simply. What happens when it's close? I don't see which capacitors are connected series ...
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Why can a isolated spherical conductor act as a capacitor?

So, a while ago I learned that a spherical isolated conductor can act as a capacitor now my question is how? I mean, a capacitor usually requires two plates to hold charge but in this case there's ...
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Force on dielectric while entering a capacitor - Connected to battery

I had seen a similar question to this as below. However it considers a charged capacitor disconnected from a voltage source. Force on dielectric slab As per my understanding from the comments, the ...
Sai's user avatar
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How does capacitance of a capacitor not depend on the distance of the capacitor to a battery?

When you consider the positive terminal of battery, wire and capacitor plate, they form a single conductor, which is polarised by the field of the other capacitor plate, but it is not polarised as ...
Lewis Kelsey's user avatar
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What happens to Capacitors at extreme temperatures and pressures?

In my University physics class [first year engineering student] I learned that "for a capacitor in a vacuum, capacitance $C$ depends only on the shapes, dimensions, and separations of the ...
William Banquier's user avatar
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What will be the difference between dielectric inserted quickly and dielectric inserted slowly in an capacitor?

CASE 1: If dielectric is inserted QUICKLY then what difference will we see in the charge , potential, capacitance? CASE 2: If dielectric is inserted SLOWLY then what difference will we see in the ...
Tejas Tajane's user avatar
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3 answers
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Charging Capacitor with grounded terminal [closed]

I had a question about the charging of a parallel plate capacitor. Let's assume the following situation: we connect the negative terminal of the battery and one of the capacitor plates to ground. The ...
Gabriel Diez's user avatar
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Charging Capacitor with one terminal grounded [closed]

I'm reading the capacity chapter of Serway's book, and I had a question about the charging of a parallel plate capacitor. Let's assume the following situation with a modification of the circuit in the ...
Gabriel Diez's user avatar
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Applying Microscopic Form of Ohm's Law to Leaky Capacitor

When we write $j=\sigma E$ in a conductor, is $E$ here the net electric field produced by the electrons and the source that drives the current? For example, inside an electrolytic cell (let us assume ...
Cognoscenti's user avatar
4 votes
3 answers
963 views

Is a battery always electrically neutral in the circuit? If so, why?

In this circuit, the sum of the charges on both the plates is 0.The sum of the charges present on the negative terminal and positive terminal of the battery is also 0 (I think). Is it possible for the ...
Pumpkin_Star's user avatar
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Distribution of charge in series capacitor arrangement

If I have 3 capacitors in series connected as shown- C1=C2=C3=C) And let a charge 'Q' is on all 3 capacitors. Then if a question is asked 'What is total charge in the circuit?' Why '3Q' is the wrong ...
SHINU_MADE's user avatar
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Discharge of a capacitor with variable backvoltage?

I understand that the voltage of a capacitor as it discharges overtime is $$V(t)=V_0e^(-t/RC).$$ I've also heard people say things like "voltage is relative. The voltage to the ground or the ...
Joseph Summerhays's user avatar
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Do conductor plates encloising charged particles exert a force on one another due to the charges induced on them? How to calculate in a 1D model

I would very much appreciate some guidance on the below. Consider a one-dimensional world as depicted in the attached figure. We have two (lets say positively charged) particles enclosed by two ...
Mainframes's user avatar
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Heat generated is zero even when current is passed through wire

A parallel-plate capacitor having plate area $20\,\text{cm}^2$ and separation between the plates $1.00\,\text{mm}$ is connected to a battery of $12.0\,\text{V}$. The plates are pulled apart to ...
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Procedure to find capacitance matrix for a network of mutual capacitances, where some nodes are left to float

Suppose we have a network of circuit nodes connected to each other via two-terminal mutual capacitances $C_{m,ij}$. Is there a recipe for finding the capacitance matrix for this network, and for ...
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2 votes
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Does parasitic capacitance contribute to the magnetic flux?

When modeling a real inductor, typically the equivalent circuit is the following one: Source A series resistance and parallel capacitor is added. This model works very well to explain the following ...
rr1303's user avatar
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Dielectrics terminology

I got confused while reading about dielectrics, so basically my question is: (a) what's the difference between a (homogenous and isotropic) dielectric and (linear) dielectric? Does the first imply the ...
tensorman666's user avatar
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Total capacitance from a capacitance matrix

I am currently doing a project where I need to find the capacitance of a multi-conductor system. Through my literature review, I read about the concept of a capacitance matrix. After more research, I ...
user392135's user avatar
2 votes
1 answer
70 views

Dielectric between capacitor

I encountered the following problem: A parallel plate capacitor has plate area $A$ and plate separation $d$.The space between the plates is filled up to a thickness $x<d$ with a dielectric of ...
tensorman666's user avatar
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2 answers
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How Do Dielectrics Affect Electric Potential Energy in Capcitors?

I am currently learning about dielectrics and capacitors in my physics class and part of what I have learned is conflicting. For starters the book says that capacitors do not interrupt current flow, ...
Julian Gutierrez's user avatar
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In JJ Thompson's experiment, why are electrons not making U turns?

In JJ Thompson's experiment, Why are some electrons able to pass through the slit of the anode, rather than hitting the anode plate itself? Even though electrons manage to get past the anode, will ...
Galaxy's user avatar
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1 answer
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How to find the capacitance between two metal sheets [closed]

Let’s say I have two metal sheets in a 2D plane. The first one has area A, the second one is infinitely long, and they are separated from each other by a distance d. How can I find the capacitance ...
user392279's user avatar
2 votes
0 answers
46 views

Where is energy lost when a system of capacitors balances itself?

Say two identical capacitors are connected like this: Two identical capacitors, each with a capacitance of 1 µF, are connected in parallel, with an open switch in between them. If a voltage of 100V ...
Shakthi Weerawansa's user avatar
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Understanding voltage conservation by capacitive coupling

At work we faced the following problem: We are working with some high voltage batteries which are located inside a casing which isolates the batteries. This means you cannot get any significant ...
Niclas's user avatar
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Charge distribution on co-planar capacitors

I'm looking for books on a complete analysis of co-planar capacitors and their electric fields at DC, such as between narrow and wide traces on a PCB. Any suggestions? I think there's a some research ...
0 votes
1 answer
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Determining vector fields in a Spherical Capacitor with Quadrant Dielectrics

I am working with a spherical capacitor consisting of an inner radius R1 and an outer radius R2. The region between the plates of the capacitor is filled with four dielectric materials, each shaped ...
fich's user avatar
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2 answers
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Question about time behaviour of capacitor [closed]

Looking at the following circuit: What would happen right after S is closed and what happens after a while of running? My idea is that right after closing there will be a short-circuit like behaviour,...
tryg's user avatar
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1 answer
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What is the electric potential difference for two spheres capacitors connected in series [closed]

Consider two spherical capacitors with Identical radii for the inner and outer spheres (let them be a and b). +q and -q charges are in the inner and outer sphere on Both the capacitors. Now I connect ...
Al-Ahsan Abhro's user avatar
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1 answer
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Energy paradox in Capacitor

Consider a sphere $S_1$ radius a and another concentric hollow sphere $S_2$ of radius b and small thickness t. Let us charge the inner sphere by some amount q. As a result -q charge shall appear on ...
Al-Ahsan Abhro's user avatar
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1 answer
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Calculating $\langle Q^2\rangle$ for circuit with Johnson-Niquist noise [closed]

I have a problem from statistical mechanics which puzzles me as I never had a course in statistical mechanics. So we have a series of a resistor and conductance and we assume that $Q/C=IR$ giving rise ...
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