# Questions tagged [capacitance]

The ability of an object to store electric charge.

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### Currents in an isolated metal exposed to an alternating uniform electric field

For example, let's look at a metal sphere between a capacitor's (infinite) plates. Let's run an AC current through the capacitor, resulting in an oscillating electric field. The charges will move in ...
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### Potential of 2 parallel plates

How can I write down a potential of 2 parallel plates (area $A$) with charge $+Q$, $-Q$ such that V(inf)=0 and V(in) is what I would expect, $Ed = Qd/A\epsilon_0$. Do I have to write a discontinuous ...
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### Can Van Allen Radiation belts act as a capacitor?

There are two Van Allen Belts at rougly 5000Km and 17000Km from the surface of the Earth each of them containing majority of one of the charges electrons and protons). Can these belts like a ...
162 views

### Negative charge on capacitor, Kirchoff differential equation with step function

I'm solving a differential equation of the form $$200q'+\frac{200}{3}q=3U_o-6U_6+3U_{12}$$ Where $U$ is the Heaviside step function. $q(0)=0 [Coulombs]$ After solving it, I get that at time $t=18$ ...
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### Energy of moving capacitor

On the following link were a discussion about energy in capacitor moving parallel to its field: Where's the energy in a boosted capacitor? My question is what happen if capacitor is moving ...
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### Capacitance changes by a factor of 3 or 9?

This is an example problem with solution in a book I am reading on electrostatics. "We have two square parallel plate capacitors with length $a$ and separation $d$ with $d<<a$. If we triple ...
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### Charging a spherical capacitance

How could one charge a spherical capacitor with a battery or any other emf source?
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### Does the Fringe effect occur in capacitors in the interdigitated form?

I am currently doing my undergrad dissertation on graphene supercapacitors. I have read that the fringe effect is a well established phenomenon on parallel plate capacitors, but does it also occur in ...
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### Energy stored in the battery of a circuit (single electron box)

Consider the following, a closed loop circuit with two different capacitors in series plus a battery that provides a voltage $V$ (in series with the capacitors). You may add a resistance if that helps....
458 views

### Discharging a LC(R) Circuit

Reading through my lecure script I encountered this example which I don't quite understand: Given is the following Circuit: At time $t= 0$ the circuit is closed, before that the circuit was open, ...
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### Electric energy density

The electric energy density for a parallel plate capacitor is $\frac{1}{2}\varepsilon E^2$ where $\varepsilon$ is the dielectric constant and E is the magnitude of electric field. In my textbook it ...
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### 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 $C$, ...
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### Gauss Law use in an example question

In the textbook (Modern Physics for Scientists and Engineers by Douglas Giancoli) it asks for a capacitance calculation. However, I want just the explanation of the electric field calculation between ...
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### Charge distribution in series combination of capacitors

its a normal series combination of capacitors,only the inner plates are placed differently,one in the beginning and one in the middle,will it not alter the charge distribution ? that is if we will ...
536 views

### What book will help me understand Electric Circuits?

I have a problem having a clear picture when it comes to solving electrical circuits. I am talking about complex circuits which contain Inductors and capacitors . The methods introduced are clear to ...
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### Connecting spheres of different capacitance

If I connect a sphere of capacitance $C_1$ to a charged sphere of capacitance $C_2$, will the charge be distributed evenly on both spheres (is the charge density going to be equal on both spheres?). ...
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### No change in voltage in a capacitor

While trying to solve this question: Photo copy of the question and answer: Question:On charging a parallel plate capacitor to potential V the spacing between the plates is halved and a dielectric ...
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### If electric field outside a parallel plate capacitor is zero then how does it stop charging after some time?

Many sources state that “charging of a capacitor stops when potential difference across a capacitor is equal to that of the battery”. But I cannot understand how this is the reasoning as, an electron ...
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### How to simplify such structures to calculate equivalent capacitance?

I am self studying electrostatics for competetive examinations but there is this series of questions demanding equivalent capacitance and I direly need a intuitive understanding of these situations.
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### What happens in the RC circuit when being charged?

Say I have this RC circuit and at the start, the switch is off (current going from left to right and the starting point is just above the battery). I understand that then the capacitor acts just like ...