Questions tagged [capacitance]

The ability of an object to store electric charge.

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In A circuit including only 1 battery, 1 switch, 1 capacitor and 2 lamps, can one lamp start lit and get dimmer, while the other lights? [closed]

In a circuit including only 1 battery, 1 switch, 1 capacitor and 2 lamps (of equal resistance), can a circuit be constructed such that when the switch is closed, lamp B immediately lights, and ...
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Basic questions about capacitors [closed]

I have some issues understanding how a capacitor works. Let's consider a simple capacitor, with two parallel plates. When we apply a voltage between these two plates, we force electrons to join the ...
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23 views

Kirchhoff's Voltage Law does not hold for a free source RC circuit?

Say I have a simple free source RC as depicted in the image below. The capacitor initially has a charge of Q on its positive plate and at time t=0 the switch is close. I use the mesh current as shown ...
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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 ...
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Electric Field in Capacitors with Dielectrics in them [closed]

The space between the plates of a charged parallel plate capacitor is shared by two different slabs of same dimensions in a parallel connection . What should the ratio of electric field in the slabs ...
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33 views

New interpretation for Heat in Resistanceless Capacitive Circuits

I have been studying RC circuits and noticed that even in a resistanceless circuit, when a capacitor is charged by a constant potential difference source, there is considerable heat generation, equal ...
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A theoretical question about matter/antimatter and capacitors

Let's assume that the experiment is done in a vacuum and there's a circuit as in the attachment. The values of voltage/resistance/capacitance are insignificant. Assume that the right terminals of ...
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48 views

Maximum Charge on the Capacitor [closed]

Question: A square loop containing an inductor of inductance $L=4 ~H$ and a capacitor of capacitance $C=2~ F$, is fixed in the plane of wires (infinitely long) carryinig time varying current $I_1=4t~ ...
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Calculating electric current between capacitors [closed]

A capacitors in a shape of a disc with radius $ a $ and a distance between the discs of $ d $ are charged with $ Q $. at $ t=0 $ we put conductive material with resistivity of $ \rho=\rho_{0}\frac{r}{...
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Why do the two plates of a capacitor store equal amounts of charge?

I understand that this happens due to Kirchhoff's law. Any current entering one side of the capacitor must have come from another part of the circuit connected to the other side. But is there an ...
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32 views

Is my understanding of the process of charging a capacitor correct?

Suppose, I have a parallel plate capacitor with copper plates $A$ & $B$ connected to a battery. Plate A is connected to the negative terminal of the battery and plate B is connected to the ...
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Finding charges on the plates of a capacitor system connected to a battery

Five identical capacitor plates, each of area A, are arranged such that the adjacent plates are at a distance d apart. The plates are connected to a battery of e.m.f. E volt as shown. The charges on ...
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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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Maximum charge of a capacitor

Suppose we have a capacitor charged with charge $Q1$ Then an electron beam hits the positive plate of the capacitor, thus increasing the charge of the capacitor (the battery will begin to deposit the ...
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What does the potential of a charged conductor mean?

While studying the unit of electrostatics, I came across the formula $$C=\dfrac QV,$$ Where C refers to the capacitance of the conductor, $Q$ refers to the charge present on the conductor and $V$ ...
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Are resistors, inductors, capacitors the only possible passive components in this universe?

I wonder whether or not there is a possibility to find another passive component (with value either $X$ or $Y$) that will change the well known RLC circuit equation below $$ L\; \frac{\mathrm{d}^2 \; ...
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Find a formula for the current after $t$ seconds, given that the voltage is initially $0$, and a constant current of value $k$ is applied [closed]

V= 1/C ∫ I dt, where I is the electric current, V is the voltage and C is the capacitance. Find a formula for the current after t seconds, given that the voltage is initially 0, and a constant ...
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Force required to insert dielectric in a capacitor connected to a battery [duplicate]

This is a sum in a reference book( H.C. Verma, concepts of phycics). A dielectric slab is being inserted in a parallel plate capacitor as shown in the diagram. The width of the plates is given to be $...
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48 views

Where is energy dissipated on charging a capacitor? [duplicate]

The energy lost on charging a capacitor can be easily found from the change in energy of the components of the circuit and the energy supplied by the battery. On charging a capacitor I know that the ...
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Self-energy of a conducting shell when we put some charge inside it

We already know that if we have a conducting sphere with total charge $q$, then the self-energy of the sphere is $\frac{q^2}{8\pi\epsilon R}$, where $R$ is the radius of the sphere. But my question is,...
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Is the work done in separating electron from neutral atom stored in its electric field?

This particular thought crossed my mind while deriving the expression for energy density of electric field in parallel plate capacitor. Energy density= $\frac12 \epsilon E^2$ It appears to me that ...
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Why is the time constant of RC circuits calculated the way it is?

I learnt about the basics of RC circuits, taking a simple case of only a resistor and a capacitor connect in series to a battery. But following this I faced several questions which involved a more ...
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Time constant of $RC$ circuit with more than one capacitor [closed]

Suppose I have three circuit components - two capacitors of capacitance $C$ each and a resistor of resistance $R$, all of which are connected in parallel. The resistance across any individual ...
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Time-domain model of a capacitor when the capacitance is varying with time

The current through a capacitor as a function of time is given by; $$i(t)=C\cdot \frac{d}{dt}U(t)$$ When assuming that the capacitance $C$ does not vary with time. But what if it does? I don't know ...
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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 ...
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Fringe Fields in a Cylindrical Capacitor v/s Parallel Plate Capacitors

I understand that Fringe Fields exist on the edges of a parallel plate capacitor like so: I was trying to figure out if a Cylindrical Capacitor would have fringe fields as well, and how they would ...
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Does $\int{\frac{1}{dx}}$ have any meaning in physics?

Recently I came across this problem : There are two identical parallel plates of length $L$ and breadth $B$ on the XZ plane . One plate passes through $Y = 0$ and the other passes through $Y = d$. ...
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How does a Capacitor generate a potential difference even after disassembling the Capacitor?

I saw a video of Walter Lewin on YouTube in which he was showing a demonstration on Capacitors. In this demonstration, he gives a charge to the Capacitor, dissembles it and reconstructs the Capacitor. ...
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What does energy stored in an electric field mean?

I know this question has been asked twice before, but i didnt find any satisfying answer there. I learnt in my class that the energy stored in the capacitor per unit volume comes out to be $\dfrac{\...
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How does charge gather on both plates of the capacitor?

In my textbook, it states that when a parallel-plate capacitor is connected to a battery, charge will flow from the battery onto both plates. How is this possible since current only flows from one end ...
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Can current flow through a capacitor submerged in electrolytes?

Imagine two flat conducting plates (3 x 3), one as the anode and the other as the cathode, submerged into electrolytes (e.g. sea water) and a DC current is applied to this apparatus. Could current ...
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Parallel plate capacitor with unequal initial charge

Suppose i have two very long parallel metal plates and i give them charges $Q_1$ and $Q_2 $respectively with $Q_1>Q_2$.The charges on the inner faces will be $(Q1-Q_2)/2 \ and \ -(Q_1-Q_2)/2$.If i ...
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I've got interesting problem from Russian school physics olympiad [closed]

I've been trying to solve this really hard problem (only for me maybe :) from Russian school olympiad for 1 week and I stucked. I tried to make some equivalent electric circuits, but I always end up ...
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Why no current passes through the middle row of capacitors [closed]

I am supposed to find the equivalent capacitance of the given arrangement of capacitors (between A and B) I have figured out that I get the correct answer if I assume that the middle row of capacitor ...
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Current flow in parallel capacitors connected with their polarities reversed

If you take two capacitors, one with capacitance C and the other with 2C, and charge them to voltages V and 2V volts, assuming CV = Q, they'd have charges Q and 4Q. Now when these two are connected in ...
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Finding the electric potential “on” a plate [closed]

So the actual question is this- To two plates of parallel plate capacitors, charges $Q_1$ and $Q_2$ are given. The capacity of the capacitor is C. Then the switch is closed. [assume both $Q_1$, $Q_2$ ...
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Dielectric and capacitor

During my course on dielectrics in capacitors, I learned that the dielectric medium if inserted between the plates of a capacitor, reduces the electric field from $E_0$ to $\frac{E_0}{K}$, $K$ being ...
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Behaviour of capacitor right after switch is closed [closed]

The flip S is closed, find charge flown from P to Q So I know at end behaviour of circuit, it should be just $ 15 uC$ just by applying kirchoff voltage law. Initially before switch is flipped, the ...
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How does a dielectric form in an electrolytic capacitor?

I have found that this happens through anodic oxidation, but can't seem to find how this happens. Why do some metals form an insulating layer when in contact with an electrolyte?
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How does phase angle impact rms Voltage in an RLC Circuit?

I have an RLC Circuit set up, with a 12Ω Resistor (though the internal resistance of the entire circuit is an additional - approximate - 140Ω), 300 mH inductor, and 100 µF capacitor. There are ...
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Resonance frequency with metal

I've made an experiment with resonance frequency of a LC circuit. One part was to place a metal (I think iron) in the middle of the induktivity of LC circuit. I measured a higher resonance frequncy as ...
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Capacitance of spherical capacitor [duplicate]

I was deriving the expressions for capacitance for spherical capacitors and i am completely confused now.please help! Outer sphere is B with radius b and inner sphere is A with radius a. CaseI- sphere ...
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Capacity of a capacitor with multiple dielectrics [closed]

The question that I have is how should I calculate the total capacity of the capacitor described in the picture below: I tried taking Air, $C_1$,$C_2$ as parallel capacitors (They should have the ...
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Capacitance of ferroelectric capacitor in saturated regime

Consider a ferroelectric plate capacitor connected to an AC source in the presence of a strong static external electric field which sets the ferroelectric medium in the saturated regime. The question: ...
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Current flow rates in capacitors connected in series

In the following question, the capacitor $C_2$ is is initially charged to a potential difference to $2\epsilon$, when the switch was open. The solution to the problem takes the rate of change of ...
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Change in distribution of charge on plates of capacitor on earthing one plate

If we consider the following situation: Now the capacitors are already charged so the potential difference between the plates is well defined but the absolute potential isn't. So what will happen if ...
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The misleading thing about this picture of capacitor

If my understanding of capacitance is correct, capacitance $C$ is defined as the ratio $\frac{Q}{V_{ab}}$ where $Q$ is the magnitude of charge on each conductor for two oppositely charged conductors, ...
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Is a capacitor a dipole? A few more questions about understanding dipoles [closed]

I recently learned about dipoles, according to its definition I was wondering if a capacitor can be considered also as a dipole? Also I was wondering what is the physical meaning of the dipole moment $...
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Liquid rising in a capacitor

Consider a parallel plate capacitor is placed in such a way that the plates are horizontal and the lower plate is dipped in liquid which has a dielectric constant k the plates are connected to battery....
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37 views

Relation between the energy of a capacitor and the force it applies [closed]

I have a capacitor with stored energy $U$. I do not understand the relation $\vec{F}=-\vec\nabla U$, where $\vec{F}$ is the force that the capacitor applies on the charge inside it.

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