Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [capacitance]

The ability of an object to store electric charge.

0
votes
0answers
33 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 $...
0
votes
0answers
31 views

Spherical capacitor with dielectrics [closed]

Consider the following system: which consists of a conducting sphere with free charge 𝑄, a dielectric shell with permittivity $\epsilon_1$, another dielectric shell with permittivity $\epsilon_2$ ...
3
votes
3answers
79 views

Why are the two outer charge densities on a system of parallel charged plates identical?

One of the ways examiners torture students is by asking them to calculate charge distributions and potentials for systems of charged parallel plates like this: the ellipsis is meant to indicate any ...
1
vote
0answers
25 views

Change in temperature of dielectric when capacitor is charged and discharged

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, $...
0
votes
2answers
28 views

Why do phasor derivations related to LCR circuits consider $V_c = I * X_c$ even if voltage and current are out of phase?

In a capacitor, the current leads by $\pi/2$. But even then derivations of of total voltage in LCR circuits using phasor diagrams assume that $V_{inst.} = I_{inst.} * X_c$ Where $V_{inst.}$ is the ...
1
vote
3answers
76 views

RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam; A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
28
votes
10answers
6k views

Is every open circuit a capacitor?

I think that even open-ended wires can let AC current flow through them, just with a low capacitance. I also think an antenna could be a capacitor and open ended. Am I thinking correctly?
0
votes
2answers
72 views

Energy dissipated across a resistor when charging a capacitor

I am a beginner in Physics and I am a little confused about RC circuits. I am working on a project in which I am measuring the power loss from a resistor when charging a capacitor in an R-C circuit. ...
0
votes
0answers
19 views

Why do we change signs arbitrarily while calculating RC circuits formulas?

When I have to calculate the formulas regarding RC circuits, for example the process of charging a capacitor, there is a discrepancy between my calculations and those of all the books I can find. Let'...
0
votes
2answers
36 views

Adding a capacitor in parallel improves power factor of an inductive circuit?

I know that to reduce power loss during transmission, we require a power factor as close to one as possible. This can be done by making $Z$ tend to $R$ which can be done by increasing $X_c$ such that ...
0
votes
1answer
42 views

Confusion with electric field in a capacitor circuit

I'm having a confusion involving a couple of laws for a capacitor: $C = \frac{Q}{V} \propto \frac{1}{d}$. The capacitance, the amount of charge the capacitor can hold for a certain voltage between ...
0
votes
4answers
59 views

Why do we use dielectric materials in a capacitor?

Okey first of I know dielectric materials used in capacitors to insulate and polarize due to electrical field created by two metal plates and then when you connect this stored energy to a system you ...
0
votes
3answers
33 views

About the capacitance of the capacitor

I would like to ask two questions here , 1. When a capacitor reaches to its maximum limit charge starts leaking and it ionises the air atoms . Well is it true ? As I'm not able to get an convincing ...
0
votes
1answer
46 views

Capacitors between two batteries [closed]

The positive terminals of both batteries are supposed to be on the right side Here I need to find the potential difference between the parts a and b. What I did was I assigned charge $q_1$ to the $2\...
-1
votes
0answers
19 views

What is the amount of work done by collapsing of two parallel charged plates?

I am trying to use integration on surface but am getting different results by Gaussian and Faraday laws. Let’s say two parallel plates with opposite charges of Q and distance of R collapse on each ...
3
votes
4answers
41 views

Find relationships between the voltage difference across capacitor and resistor

I'm trying to learn kirchhoff's law. but im stuck on how to solve for a circuit that has both a resistor and a capacitor. How would you proceed?
0
votes
1answer
47 views

LC-circuit and the current

A capacitor and a coil are charged in the LC circuit. When the circuit switch is closed, the current starts to flow. In theory the oscillations and the current do not deteriorate, but why in reality ...
0
votes
3answers
50 views

What does leakage of charge in plate and isolated spherical capacitors mean?

I've read quite a lot of times about leakage of charge in capacitors, but what does it exactly mean? Do we see sparks? Or is it some current flow? Or something else? Say I have a charged sphere, so ...
0
votes
2answers
56 views

Differential equations for the LC circuit

On wikipedia one can find that the DE for an LC circuit is given by $$\ddot I+\frac{1}{LC}I=0$$In one of my papers however I found the equation $$\ddot Q+\frac{1}{LC}Q=0$$ and I've been confused by ...
2
votes
1answer
56 views

Resistor Capacitor circuits

I am a high school physics teacher and came across some issues today that I am unable to explain. We made a circuit with an $11$ V power source connected to a $100~k\Omega$ resistor and $100~\mu F$ ...
0
votes
2answers
64 views

How can AC current pass through an open circuit?

I think for example for oscilloscope what gets signal just in one wire and how can even ac go through only one wire?
1
vote
1answer
26 views

Resolve The Envelope Detector Circuit

I was working on a little project and I was wondering if the envelope detector circuit could be resolved analytically. Let me explain. The circuit is the one shown above, I know the values of $C$, $R$...
0
votes
0answers
22 views

capacitance of cube skeleton

A cube of 12 capacitors is very common problem. find capaciance accross edges we get 12c/7. But lets say we have 8 more capacitors involved now. that is we have capacitors at all sides of cube and ...
1
vote
1answer
43 views

Is a radio receiver antenna a capacitor?

I think so, but its capacitance should be very small, so how can the antenna correctly receive the signal, the low capacitance wont bother the signal?
0
votes
1answer
36 views

Why is charge proportional to capacitance? [closed]

I'm having trouble understanding why the charge is multiplied by the dielectric constant in the following question: A parallel-plate capacitor has capacitance C0 = 5.00 pF when there is air between ...
1
vote
5answers
80 views

Why is capacitance increased with a dielectric rather than reduced?

So conceptually, if a capacitor is connected to a voltage source, and if you decrease the distance between two plates, the electric field in between the plates increases. This means that you can hold ...
0
votes
1answer
33 views

How do you calculate the capacitance of a parallel plate capacitor with multiple dielectrics? [closed]

My question is how would you go about calculating the capacitance of a parallel plate capacitor which has two mediums in between the parallel plates. I am aware that for a regular parallel plate ...
0
votes
1answer
33 views

If voltage across a capacitor GROWS till maximum in finite time then, is it possible that the capacitor also reaches maximum charge in finite time?

When a dc-voltage V is applied to a capacitor C, the charge on it takes infinite time to reach maximum value ...
0
votes
1answer
80 views

Influence of an external electric field on an uncharged capacitor

Influence of an external electric field on an uncharged capacitor. Fig A shows an uncharged capacitor with no external electrical field. There is no net charge on each of the plates. Since the ...
0
votes
1answer
51 views

Does an uncharged capacitor in a non uniform electric field have a voltage difference at its terminals?

If an uncharged capacitor was placed in a dc field would there be a voltage difference developed on its terminals related to the different locations of the two surfaces in the voltage field? Would the ...
1
vote
2answers
33 views

Charge decay (leakage) of a charged metallic sphere

I have a spherical ball (charged to a specific charge) and the charge on the ball leaks to the surrounding. I observe that the charge on the ball reduces exponentially. Can anyone give a theoretical ...
0
votes
2answers
16 views

Can we define rms current for pure inductive and capacitive ac circuit?

For a purely inductive and capacitive ac(sinusoidally varying) circuit, average power dissipated across a capacitor or an inductor is zero. Then does that mean RMS current is zero?
0
votes
2answers
33 views

What happens to a system of capacitors when a dielectric is inserted into one of them?

sorry for my English. While doing some homework I've stumbled upon this "circuit": the system is connected to the same potential difference through a generator that is connected to points A and B. ...
0
votes
1answer
28 views

RC circuits - what can we interpret when the voltage across the capacitor is equal to zero?

When applying the law of addition of voltage in RC series circuit with alternating sinusoidal current, we notice that voltage across the generator is equal to the sum of the voltages across all other ...
0
votes
2answers
86 views

Common potential of two capacitors

I read in my textbook that when two isolated capacitors are connected to each other, redistribution of charge takes place in such a way that they both acquire a common potential. My question is why ...
0
votes
2answers
69 views

Current without EMF in AC capacitance circuit

In AC circuit with only capacitance, current in circuit is maximum at time t=0 but emf of source is E=0 at t=0 , how can this happen, How can current flows without emf.
0
votes
2answers
62 views

Charging and discharging a capacitor [closed]

So from what I understand, in the case for the charging capacitor, I understand the voltage across the capacitor as well as the charge can be given as the function of time: $$V(t)=\epsilon(1-e^{-t/RC}...
0
votes
2answers
58 views

RC circuit confusion [closed]

I was doing some RC problems in A levels, and in ine of thr problems it was about a circuit attached as a picture: My question is can someone clearly explain to me why when time goes to infinity , ...
0
votes
2answers
99 views

How is a capacitor implemented in Kirchoff's Loop Rule?

I'm real stumped here. I may be missing something, but I'm genuinely perplexed as to how one would add a capacitor to the list of elements being added to an equation through Kirchoff's Loop Rule (KVL)...
0
votes
1answer
29 views

Ratio of charges between capacitors in parallel and in series [closed]

Context: this is a multiple choice question, but no explanation is given Question: three capacitors of equal capacitance are connected in the following circuit. Determine the ratio of charge in ...
0
votes
0answers
11 views

Is the permittivity of a dielectric medium measured by application of radio frequency of 1 KHz and a resonant circuit of 1KHz are same?

I am working on a procedure in which I assess the dielectric constant of a medium by subjecting the dielectric medium to electromagnetic radiation of certain frequency (or the medium is subjected to a ...
1
vote
1answer
73 views

How to differentiate Capacitance (Italized C) and Coloumbs (regular C) on paper [closed]

I am doing a question on capacitance and coulombs. I got the answer correct, but I was wondering how a physicist, when doing the calculation on paper, would differentiate a C and C?
0
votes
1answer
34 views

How to compute the self-capacitance of a conductive shape?

(Depending on the answers given, this question might be better suited for Math.SE, but I don't think so.) I recently learnt about the notion of self-capacitance of a conductive shape, which now seems ...
0
votes
2answers
53 views

Question on capacitance

I am recently trying to learn electrics on my own but am a bit confused with regard to capacitance. By Gauss law, I understand that the electric field from a single parallel plate results in: $$ E = \...
0
votes
0answers
95 views

Capacitance of spherical capacitor when inner sphere is earthed

Consider the following derivation: (Source: http://www.ncert.nic.in/html/learning_basket/electricity/electricity/electrostatics/inner_sphere.htm) If a charge of $+Q$ coulombs is given to the outer ...
1
vote
1answer
73 views

Partially Filled Capacitors

I know that, for partially filled capacitors, one treats the space between the capacitor plates as two or more capacitors either in series or parallel. However, I don't fully understand why the ...
0
votes
0answers
33 views

rotating capacitor question

Imagine a simple setup. I have a copper disc and another copper element held close to the disc at one of it's sides, this element is stationary but the disc is rotating, the part between the disc and ...
3
votes
1answer
60 views

Why do we not have devices like inductors or capacitors to hold gravitational field? [closed]

I know that a capacitor can store electric field and an inductor can store magnetic field. So is there a way that gravitational field field can be stored in any such device. Also we do not have a law ...
0
votes
2answers
51 views

Does the capacitance depend on the distance?

I know that the Capacitance of a capacitor does not depend on the Voltage (because it is a measure for how much charge a capacitor can hold) and it largely depends on the Area i.e. it holds that : $...
0
votes
2answers
117 views

Van de graaff generator, Leyden jars and capacitance

How will the capacitance of a typical desktop van de graaff generator be affected when connected in series to a group of some 5-10 Leyden jars? I know that the capacitance is decreased in series ...