Questions tagged [capacitance]

The ability of an object to store electric charge.

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Resultant Capacitance of a capacitor having a combination of dielectrics

In a few questions, I have some confusion on how to take the resultant capacitance(Of a parallel plate capacitor) with a combination of dielectric in between. Here is a an example (From JEE Advanced ...
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Analytic formula for finite parallel plate capacitor with arbitrary plate distance

Is there an analytic formula for the electric field in a (rectangular as well as circular) parallel plate capacitor with finite plate size for arbitrary plate distances?
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Is the work required to charge a capacitor the same as the energy stored by the capacitor?

If you have a capacitor and you need to calculate the work required to charge it, would this simply be equal to the energy that the capacitor holds?
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Work in increase charge in a isolated conducting sphere

The potential of an isolated conducting sphere of radius R is given as a function of the charge $q$ on the sphere by the equation $V = kq/R$. If the sphere is initially uncharged, the work $W$ ...
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Find the charge, in microcoloumb, on the capacitor $C$. Internal resistance of the source is to be neglected (Take $E=9V$, $C=2\mu F$) [closed]

So, I know how to do this by the junction law, but I'm not able to get the right answer when using equivalent capacitance manipulations. Potential difference across resistor R = 3V Therefore, by ...
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Why is the induced charge on inner shell of a spherical capacitor considered? [closed]

In the above type of spherical capacitor, it was given thas as the bettery is only connected to outer shell charge will only be present there and as the other end is connected to earth(thereby assume ...
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How do I achieve 50Hz using an astable multivibrator? [migrated]

So based on the $f=1/1.38RC$ equation I came up with the conclusion that $R$ must be 69000 ohms and $C$ must be 1000uF, is this correct? And I have a side question: If I am charging a capacitor ...
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How does current/component voltage phase difference calculated in pure circuits remain the same for mixed circuits?

In class, we derived the phase difference values between the component voltage and the circuit current for pure inductive and capacitive circuits. Later, while doing LR, RC, and LC circuits, we used ...
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What trigger a capacitor to discharge when I connect a wire externally if $E$ is 0 outside?

I know that there is a $Vab$ between the plates but I know also that the charges attract each other in the inside side of plates. So, the questions are: what happens when I just connect a wire on both ...
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Capacitance of plate or Rectangular prism

I am trying to calculate the capacitance of a rectangular prism. This would be the self capacitance with reference to infinity. If that is a tough Job, I could settle for approximating the capacitance ...
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Capacitor, charges, resistance and much more

I am not able to understand if charges are circulated to charge the capacitor even if the circuit is open, then if we connect a bulb in between the capacitor and cell then that charge charging the ...
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Capacitors charging, resistance much more?

I am overwhelmed by the amount of doubts i am having regarding this device (CORRECT ME WHEREVER I AM WRONG PLEASE) First things first if we connect a capacitor using two ideal wires (for each plate) ...
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Experiment 3: Capacitors in series and parallel circuits

Can someone please explain me the theory that explain that the total capacitance in a parallel circuit is the total of the individual capacitance of each capacitor added together.
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Capacitor creates uniform electric field and the electric potential decrease. By solving capacitor equation for electric potential conversations [closed]

Capacitor creates uniform electric field and as the charges move, electric potential decreases. State some assumptions which are taken into consideration while solving Capacitor equation for electric ...
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Underdetermined system of equations for infinite parallel plates?

I am trying to mimic the separation of variable method to finding the electrostatic potential. For instance section 2.9 in Jackson 2nd edition. Consider two infinite plates of potential $\pm V$ ...
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Potential difference in parallel plate capacitors

I calculated the potential gain/difference for these two cases. And found that, voltage difference would be higher for the parallel plate capacitor (2nd one). So from my understanding, the capacitor ...
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Where should I put a fixed amount of dielectric to maximize the capacitance between two widely separated plates?

Imagine that I have a capacitor made from two parallel finite plates, separated widely enough that there is a significant fringe field. (Thus, the capacitance is not given exactly by $\epsilon_0 A/d$....
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Misunderstanding of Potential Energy with Dielectrics

Let there be two conducting, square plates, lengths $l$ and charges $Q_1$ and $Q_2$ respectively. They are separated by distance $s$ and the intervening area is filled with a linear dielectric with ...
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Why exactly do capacitors charge and discharge exponentially?

Hi this is my first time posting so please feel free to correct me on any formatting errors I may make. I understand that as a capacitor charges, the amount of electrons that are deposited on one ...
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Why does a fully insulated conductor dropped into the water of a charged Leyden jar get charged?

I have tried this experiment for some time and I would like to know what's happening. if I charge a Leyden jar with voltage multiplier and I place a fully insulated or covered conductor into the water ...
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Does concept of capacitance make sense for bodies other than metal like dielectric or bad conductors?

Today I came across this question. Just to give an estimate of the capacitance of the body I tried to model it with a dielectric cylindrical shell, the dielectric being the fur of the cat; something ...
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Why significant change in permittivity can be observed for parallel plate capacitor? (multiple dielectric plates)

I have done the measurements of paralle plate capacitor with HM8018 LCR meter to measure capacitance and later, with known parameters such as surface area and separation distance, calculate ...
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Generating alternating current using capacitor

I'm working on a device to use the electrostatic electricity to generate electricity. I have read that the electric field is far more powerful than a magnetic field but less in recent years have ...
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1answer
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Disconnecting RC/RL-Circuit prematurely

Lately I've been dealing with some RC/RL Circuits, and as I was working on a problem, I came across a peculiar issue, which I haven't properly resolved so far. The given equations that describe $i(t),\...
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Self and mutual capacitance

Consider having a positively charged plate with charge +Q and potential at surface +V. Then, its self capacitance equals Q/V. Now, i have a similar plate with charge -Q and potential -V. The plates ...
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Charge in the each capacitor when connected in parallel

Consider a situation where we have three capacitors of capacitances A, B and C connected in parallel to a battery of emf V. The equivalent capacitance of the combination would be A + B + C. The ...
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When we charge a capacitor via a battery then why does exactly $1/2$ of the work done by the battery get converted to heat? [duplicate]

I know the $\frac{QV}{2}$ & $QV$ stuff but I want the logic. You would say it's due to the resistance that the work gets converted to heat. But, why is it that exactly half the value of work done ...
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How to approach this problem? (electrostatics, capacitors)

The problem: A flat capacitor is made of two strips of width $a$ and length $l$. The distance between them is $d$. Determine the capacitance of that capacitor if you roll it into a multi-turn roll of ...
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Potential and capacity of parallel plate capacitor [closed]

Given is a capacitor consisting of 2 sheets stretching out infinitely at $z = \frac{d}{2}$ and $z = -\frac{d}{2}$ which has a surface charge density $\sigma = \frac{Q}{\Delta F}$. It's potential is ...
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Why is my approach to this problem about charging an uncharged capacitor with a charged capacitor wrong? [closed]

This is the above mentioned problem : Using a battery a10 pF capacitor is charged to 50V and then the battery is removed. After that, a second uncharged capacitor is connected to the first capacitor ...
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If no current is able to flow through a capacitor what will be the node voltage on the other end of the capacitor opposite the voltage source?

I'm working on a simple circuit problem including a capacitor and I am calculating the node voltage Va. By using KVL, I find that Va is 5V. But how does the 5 volts appear on at Va if it is not ...
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How to apply Gauss's law when dielectric constant in a capacitor varies continuously?

Let's say the problem is to compute the capacitance of a cylindrical capacitor with a dielectric material between the plates. The capacitor is considered to be long enough to ignore end effects. The ...
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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 ...
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Magnetic Field in a Leaky Capacitor

Consider a spherical capacitor which is made of two concentric spherical shells. The capacitor is charged so that outer shell carries a positive charge and the inner shell carries a negative charge of ...
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The volume enclosing the charge in Gauss's law: does it have to be simply connected?

I was trying to apply Gauss's law to a simple problem: Find the capacitance of a cylindrical capacitor. Inner radius is $a$ and outer radius is $c$. The space between the plates is a dielectric ...
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Potential with plates at $V$ and $-V$

Consider two very large plates, one of which is lying on the $xz$ plane and sitting at a potential $+V$, and the other forming an angle $α$ with the aforementioned plate, attached to the other at the $...
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How is dielectric constant both $E_{net}/E_o$ and $ε/ε_o$?

The questions asks that, given the (surface) charge density (σ) on the plates of a parallel plate capacitor and dielectric constant (k), what would be the magnitude of induced charge density on the ...
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Grounded/Earthed electric circuits

I have a problem here that involves a circuit that is grounded at the point shown at the bottom the circuit. The units marked with C are all capacitors and Uv is a voltmeter. I haven't seen any ...
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Analog of harmonic oscillation to electrical circuit

Equation of a damped harmonic oscillator under varying force $F$ is: $$ m\dfrac{\mathrm{d}^2 x}{\mathrm{d}t^2}+\gamma m\dfrac{\mathrm{d}x}{\mathrm{d}t}+Kx=F $$ And the electric analog to this is: $$ L\...
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Charge Redistribution on Capacitor Plates

Say, I've got two Large Conducting Sheets (intention : to neglect end effects). My question is quite fundamental and relies on the basic understanding of Charges. Now, I bring these two plates ...
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How to find the transfer function for steady state? [closed]

I can not find the transfer function for sinusoidal input could you please help me find out the solution or at least where to start! i have found the transfer function Vo(s)/Vi(s)=1/(2j+1) but still ...
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Confusion about Electric Permittivity

I have learned about electric permittivity in two contexts: How much a medium reduces the strength of the electric field (Like if I have a charged ball inside a vat of oil, the oil will polarize and ...
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Electric field between two conducting plates both with zero potential and volume charge density between them

The questions says that two very large, conducting, parallel plates separated a distance $2a$ contain a uniform volume charge density $ρ$ between them and they both have zero potential, the ...
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Energy dissipation due to displacement current

Consider the following problem: An isolated capacitor made of parallel circular plates of radius $a$ separated by a distance $d \gg a$ is charged such that there is a potential difference $V$ between ...
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How does a capacitor get charged instantly in AC whereas it takes infinite time in DC? [closed]

I have seen when a capacitor is connected to a dc source it takes infinte time to charge, but when connected to ac it takes the potential of the source instantly, probably the approach in the books is ...
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Confused about a question on RLC circuits [closed]

Question: Find the current 'I' after a long time. I got that the answer is 2.66mA, but it is not the correct answer and I don't know why. There is no current on the capacitor after a long time because ...
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Which side of the capacitor is at higher potential?

Our physics teacher gave us a simple problem in our class related to the diagram below. The current increases at the rate $4 {\rm As^{-1}}$ and we are to find charge on the capacitor when current is $...
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Conceptual understanding of how a battery ensures that a capacitor has the same potential difference as it?

I was wondering how exactly a battery is able to ensure that a capacitor connected to it would have the same potential difference as it. Like, thinking about a battery similarly to a capacitor, I ...
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Sizing capacitor and power factor

The first formula is the reactance that you need to improve your PF to your desire (). The second formula given is use to calculate the capacitor needed to get the desired reactance (QVAR) I am ...
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In a free underdamped RLC circuit, when the current is maximal, is the voltage in the capacitor zero?

I am in my last year of high school. We are studying free RLC circuits but we're not diving too deep into the theory. We know how to derive the differential equations governing charge, current and ...

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