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Questions tagged [capacitance]

The ability of an object to store electric charge.

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RC circuit Laplace Transform [on hold]

I've got the equation for RC circuit: where F[s] was initially $e(t) = V_{0} sin(ωt)$ before Laplace Transform. How to calculate function $V_{2}(f)$, where $f$ is the frequency?
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14 views

Can we find capacitance of following capacitor [on hold]

cosider a parallel plate capacitor of area A and d be distance between plates of capacitor and a dielectric of dielectric constabt K let its thickness be t such that t less than d and the dielctric ...
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Capacitor stores 10μC charge when joined across a cell.The gap b/w the plates is filled with a dielectric a charge of 20μC flows through cell.Find K [on hold]

A capacitor stores charge 10μC. Later a dielectric medium of constant 'K' Is placed in between the plates of capacitor such that 20μC charge flows through the battery. What is value of 'K' of medium ?
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23 views

Evaluating current flow in circuit [on hold]

How to find the flow of charge in each prong of the circuit.
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0answers
24 views

Connecting one lead of capacitor to a certain charged object (to get a potential difference)

Setup-A charged sphere , connected to one plate of capacitor , other lead of capacitor is free. Question-Will the capacitor plates go through a charge redistribution ? Arguments/Counterarguments-I ...
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3answers
69 views

Is a complete circuit required for capacitors to redistribute charges?

Suppose I have two capacitors of different capacitance $C_1$, $C_2$and they have been charged prior connecting by voltage of $V_1$ and $V_2$ respectively the positive plate of one capacitor is ...
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2answers
46 views

How do we extract energy from capacitors?

I have an intuitive reasoning for the use of capacitors. I think that it is used to store electrical energy. Without going in much detail in engineering and being at an introductory level of ...
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29 views

How to use energy conservation in following case [duplicate]

A capacitor of capacitance C is intially uncharged is connected with a battery of emf ε.Find the heat dissipated in the circuit during charging?How can we apply energy conservation although there are ...
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question on capacitor [on hold]

A capacitor of capacitance C is intially uncharged is connected with a battery of emf ε.Find the heat dissipated in the circuit during charging?
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13 views

Plane capacitor with two dielectrics [on hold]

A parallel-plates capacitor has plates separated by a distance 1.0 mm. The space between the plates is completely filled with two slabs made from different dielectric materials. One slab has thickness ...
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0answers
17 views

Is the potential difference across any capacitor equal for n identical capacitors connected in series? [duplicate]

(https://i.stack.imgur.com/Pfit8.jpg) Is the potential difference equal for n identical capacitors connected in series? Please go through the image as my confusion lies there.
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Is the potential difference equal for n identical capacitors connected in series? [on hold]

(https://i.stack.imgur.com/Pfit8.jpg) Is the potential difference equal for n identical capacitors connected in series? Please go through the image once as my confusion lies there.
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1answer
29 views

How does the stud finder work?

My textbook explains how a type of stud finder works by an illustration. What I can’t understand is how does the piece of wood have an effect on the capacitance of the plates when it is so far away ...
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2answers
46 views

Impedance of an LCR circuit

So I am trying to understand how to find the impedance of the parallel LC component of this filter circuit. I am given that the transfer function $\mathbf{T}_C = \dfrac{\mathbf{V}_{out}}{\mathbf{V}_{...
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0answers
32 views

What is the net capacitance of this circuit? [closed]

The only thing I can think of is to use Y Delta conversion but I'm not sure it'll be applicable .
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3answers
54 views

Why is the force required to keep a parallel plate capacitor EQ/2?

In our electrostatics course we were talking about how if you increase the separation of the plates by a tiny amount, then as the field is still constant, the potential difference increases. This ...
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4answers
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Why is there no current between two capacitors connected in series?

I want to ask a question about the figure below. Why the current does not flow from $-Q$ term to $+Q$ term or from a to b since there is a voltage?
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2answers
63 views

Does Kirchhoff's rule break down as it applies to capacitors

A homework problem asked me to find the voltage across a series of capacitors after they came to equilibrium. Essentially a capacitor C1 with a capacitance of 6.0 F is charged until the potential ...
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5answers
80 views

If current through a resistor is zero, does the circuit break?

I'm really confused. I'm studying about how capacitors are charged, and I learnt that there's a resistor attached in series with the capacitor when it is being charged. When the capacitor is fully ...
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3answers
59 views

Charging capacitor in an incomplete circuit [closed]

I have 2 confused questions regarding the below circuit. please help me out How will the capacitor even charge in the following scenario when the right side of the capacitor is not connected to ...
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1answer
28 views

Conduction current for parallel-plate capacitor

I am reading Sadiku's Elements of Electromagnetics and here is the proof given to show that conduction current = displacement current for parallel-plate capacitor. Displacement current: \begin{align*}...
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1answer
18 views

Repulsive force from charge accumulation in a capacitor plate?

During a charged state of a capacitor (Regardless of the type of capacitor), Simple parallel plate: .png Parallel plate with dielectric material in the gap: ]3 Supercapacitor: How is the ...
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1answer
20 views

Is it possible to create and control a magnetic field in a dielectric material?

A capacitor is usually formed by an insulater between two conductive plates. By applying voltage difference between the plates we create an electric field within the insulator in one direction. If you ...
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1answer
36 views

Electric potential and voltage

A capacitor is connected to a battery with constant voltage. If you approach one of the plate to the other, what happens to electric potential? I already have an answer to this question but it's ...
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0answers
33 views

Calculating the self capacitance of a rectangular electrode with a dielectric on one side

I am trying to derive an expression for the capacitance of a rectangular electrode with a dielectric material of thickness $t$ and relative permittivity $\epsilon_r$ in contact with one side, sized ...
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1answer
40 views

Neglecting capacitor from circuit

Take a look at this circuit : This question is answered in $Serway$ $7th$ ,And the book neglected 8 Farad capacitor because the voltage between $c$ and $d$ is zero. My questions is : $1.$Should not ...
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1answer
26 views

How can we analyze electronic capacitors in series? [closed]

Two capacitors are in series, such as in this circuit diagram: When doing a circuit analysis, how can we describe the voltages and charges across the two capacitors?
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1answer
64 views

Does the voltage of the battery change if you use it? [closed]

If you use the battery to charge a capacitor does the voltage of the battery decrease or still the same? Does the voltage of a capacitor decrease if you use it to charge another capacitor?
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1answer
41 views

Redrawing circuit rules

Take a look at this circuit: Is it allowable to redraw the circuit like this ? Can I move cd wire until it merge with b junction ? Can I move e point like what I did in the figure ?If yes why this ...
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1answer
44 views

How to solve these kind of electric circuit? [duplicate]

This question from Physics For Scientists And Engineers 7th page 746. After redrawing , Actually I cant see any two clear capacitors that we can be combined , First we cant combine $C$1 with $C$2 ...
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1answer
23 views

How is current affected by a charging capacitor in parallel to a resistor?

Imagine a circuit with a battery followed by a lightbulb and an uncharged capacitor in parallel. Next to it is an open switch. When I close the switch completing the circuit, does the brightness of ...
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0answers
19 views

Regarding induced magnetic field due to changing electric field

I am trying to solve this question: My approach was to first notice that the electric field is decreasing, therefore the change in electric field is to the left. If I point my thumb in the direction ...
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0answers
12 views

Effects generated from a supercapacitor placed in a time varying external magnetic field?

The diagram above, showcases the simple outlook of a supercapacitor's interior and combining it with a full circuit loop. If an exterior magnetic field is introduced in all the operating states of a ...
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1answer
49 views

Calculating the potential difference of a capacitor [closed]

As far as I know the voltage between the plates of a capacitor will be reduced due to discharging. I wonder how much the voltage would be changed if the capacitor lost %25 of its stored energy. ...
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2answers
88 views

Parasitic capacitance in real resistors

Typically, I'd assume (A) is only a justifiable answer when the two metal end caps have essentially infinite area, or when the spacing between end caps is far smaller than their respective areas, in ...
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1answer
41 views

My fingers are sparking large source of electricity when I touch plastic boards covered with polythene

Still I don't understand why am getting such voltage & it's the same feel that I touched 250 voltage of current. Also when I put two fingers on opposite direction (when I am removing polythene ...
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0answers
23 views

$j$-$\omega$ method alternating current circuit help [closed]

I'm suppose to calculate the current and the phase angle. Can someone please tell me if this is the correct solution?
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1answer
32 views

CombinationsDielectrics in parallel

I was reading about dielectrics and wondered why there was no formula for their parallel connection between two parallel plate capacitors. So I thought of deriving it myself. Let $k_1$ and $k_2$ be ...
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4answers
37 views

Finding the charge on a capacitor (RC circuit)

I am having trouble finding the charge on the capacitor for $t\rightarrow \infty$ after the switch has been closed at $t=0$. I already know the current $I$. I also have to find out on which sides the ...
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2answers
51 views

How Do I Calculate the Potential of System?

I was doing my homework when I came across this question: Three equal point charges, each with charge $1.40 \, \rm\mu C$ , are placed at the vertices of an equilateral triangle whose sides are of ...
2
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2answers
50 views

Railgun design, which is preferred, voltage or farads?

I am building a rail gun for a physics project, but I am confused on whether to use capacitors like 2.7V 500F capacitors or a 400V 3300uF capacitor. Most tutorials seem to use many 400V ones in ...
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0answers
41 views

Proper utilization of Ampere’s Law

I am tasked with finding the magnetic field due to a bus bar, which seems to have the exact same set up as Problem 7.62 in the fourth edition of Griffiths' textbook on Electrodynamics. To which I ...
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1answer
28 views

Why does potential decrease when a dielectric is introduced?

Here is a problem that I have encountered: A parallel-plate capacitor has the space between the plates filled with a slab of dielectric with constant $K_1$ and one with constant $K_2$, each of ...
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2answers
72 views

Why is this method of solving this capacitor problem wrong? [closed]

The problem was to solve for the capacitance of this system if initial capacitance was C. I solved it using the method which has been given as wrong.My question is that why is potential difference ...
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2answers
39 views

Why do we define Energy density

So we define the electrical energy density $(\bar U)$ between a parallel plate capacitor as $$ (\bar U) = \frac{1}{2} \epsilon_0 E^2$$ where $E$ is the electric field between the plates usually given ...
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1answer
25 views

capacitor and electrostatic field

Is there any electrostatic field around the leads of a charged capacitor? Let's take just the negative one. If I take a piece of tissue and put close to that terminal it will attract or repel the ...
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1answer
52 views

Why does the Voltage of a Capacitor change in an alternating current (AC)?

I have a question about charging a capacitator in an alternating current. If the process starts the current charges the capacitator, therefore the voltage on the capacitator will be increased. Now the ...
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1answer
99 views

Would Kirchhoff’s rules not hold in this circuit?

On my E&M test I was given the circuit diagram below and asked to find the charge on the capacitor after a long time or as $ t \to \infty $. In class we had used Kirchhoff’s voltage rule on the ...
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0answers
19 views

Metal Oxide Semiconductor (MOS) Capacitor strong inversion

Why the electron bands in the Body of the MOS capacitor do not bend much futher after the threshold voltage is applied? What stops them from doing it? For reference Modern Semiconductor Devices for IC ...
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0answers
149 views

Imaginary Capacitance and Imaginary Inductance interpretation [closed]

Today I came across with Complex Capacitances and Inductances for the first time: $$L(j\omega)=L_{real}+jL_{imaginary}$$ $$C(j\omega)=C_{real}+jC_{imaginary}$$ So I started looking at their meaning. ...