Questions tagged [capacitance]

The ability of an object to store electric charge.

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2
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1answer
30 views

Current in RC circuit

Why is current drawn in an RC circuit (in a circuit powered by DC voltage supply) independent of the capacitor used? While the capacitor is charging current drawn from the battery only depends on ...
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0answers
40 views

A Simple RC Circuit [on hold]

This is the most simple Rc circuit (i have just started learning) .My questions regarding this is- (This is a dc voltage supply) Will capacitor get charged by the potential drop of resistor or ...
-1
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0answers
11 views

Engineering physics capacitor [on hold]

A long cylindrical conductor has length 1m and is surrounded by a coaxial cylindrical conducting shell with inner radius double that of long cylindrical conductor. Calculate capacitance for this ...
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0answers
10 views

$C$-$V$ characteristics of MOS capacitors for different material [on hold]

For C-V curve below for 3 different materials, (Si, InAs, InSb). What material will be corresponding to curve A/B/C? My understanding is that C is inversely proportional to the dielectric constant in ...
0
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1answer
44 views

Why is the electric field of a conducting sheet of charge double the electric field of just a sheet of charge?

I was reading Feynman's Lecture on the Application of Gauss' Law and I came across this: Source This really confused me. What are the "other" charges he talks about? How does the additional field ...
0
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1answer
32 views

LCR circuit (AC source) potential difference across capacitor

For a LCR circuit connected to AC source of emf$$E= e\sin(ωt)$$ and let the current in LCR circuit be I then $$I=i*\sin(ωt+Φ)$$ then it is given that potential drop across the capacitor is V.ie$$V=-...
3
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3answers
81 views

Why don't capacitors hold charges on the outer walls of the plates?

Suppose I have two metal plates in a vacuum and I give this system some electric charge,the charge would distribute itself according to Gauss law on both the inner and outer walls of both plates...but ...
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0answers
18 views

Force of attraction in capacitor [duplicate]

In a question, it was asked the force of attraction between the plates of a parallel plate capacitor. and it was solved as $$\frac{(1)(C)(V^2)}{2}=(F)(d)$$ $$F=\frac{(1)(C)(V^2)}{(2)(d)}$$ and I ...
-3
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0answers
43 views

I got the answer but I suppose I did not understand the question very well [duplicate]

See as per the question, The Inductor pretty much will induce emf due to magnetic field and not due to other coil/current nearby. Thus I used $E= - d(phi(t))/dt$ as the induced emf. Then using (...
0
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1answer
22 views

Why are the times at which max rate occurs different for the energy of a capacitor and the battery

When charging a capacitor the rate at which the battery provides energy is maximum at $t=0$ but the time at which the rate of increase in the energy of a capacitor is maximum is $t=CR\ln(2)$ (where $C$...
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3answers
339 views

What happens when electrons reach the battery?

We have a capacitor which is connected to a voltage source. The top plate of the capacitor is connected to the positive terminal of the source. Therefore, electrons go from the top plate to the ...
0
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1answer
39 views

Doubt in the derivation of Gauss's law in dielectrics

so in the 2nd page,when the dielectric material is introduced the gauss's law becomes $$\oint _ { S } \vec { E } \cdot \vec { d S } = \frac { ( q - q _ { i } ) } { \epsilon _ { 0 } }$$.But my ...
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0answers
43 views

How is the 4th option related to the question? [closed]

I cant seem to understand the 4th option at all. How is it related to the question? Can you please help?
0
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1answer
44 views

Force in an isolated capacitor when a dielectric slab is introduced [closed]

my question is about capacitance: a dielectric slab is inserted between the plates of an isolated capacitor. The force between the plates will remain unchanged. how? I mean the knowledge I had gained ...
4
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0answers
67 views

Voltage propagation along a wire [closed]

Let's say you have a wire connected to a device that you can switch between high-voltage and ground voltage. The wire is not connected to anything on the other end. You're observing the voltage in two ...
1
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0answers
39 views

Why am I getting two different expressions for capacitance? [duplicate]

The question is: A capacitor of capacitance C1 is connected to a battery of potential V0. The battery is then disconnected and a second capacitor of capacitance C2 is connected to the first ...
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2answers
37 views

Capacitors connected in parallel with a switch attached [closed]

What does it mean when they say capacitor reaching equilibrium?
3
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2answers
129 views

Circuit - solve Kirchhoff's laws with determinant?

Here is an exercise from my textbook. ]1 At first I solve it by using Kirchhoff's laws directly and using complex impendance: $$U_{in}=\frac{1}{Cs}(i_1-i_2)+i_1R_1$$ $$0=R_2i_2+\frac{1}{Cs}i_2+\frac{...
0
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1answer
18 views

Electric potential difference between capacitor's plates, doubt about the sign?

I'm trying to solve a doubt that has taken me away way too much time and so I'm asking here. In our lectures we defined the electric potential difference between a point A and B as the line integral ...
3
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2answers
81 views

Applying Kirchhoff Rule to an LC circuit

In a simple LC circuit (just one capacitor and one inductor), using the Kirchhoff rule has $$\frac{Q}{C} + L\frac{dI}{dt} = 0.$$ But isn't the voltage drop across an inductor $-L\frac{dI}{dt}$? What ...
4
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2answers
44 views

Common potential in Capacitors

If two isolated charged capacitors (of different capacitance) are connected in parallel to each other they acquire a common potential. But suppose if i connect positive plate of one capacitor to ...
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0answers
13 views

Difference between Capacitor and a battery [duplicate]

Capacitor stores electric charge and battery also stores electric charge. SO whats the difference between them?
0
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1answer
37 views

Electric field between capacitor plates

When we try to find the electric field between the capacitor plates, what is the right way to do it? This is one of the ways I've seen and I don't understand why: Using a Gaussian cylinder on the ...
0
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0answers
17 views

Capacitance of insulated conductor with charge on insulation surface

I have an insulated wire at high voltage (10s of kV) running above a conducting ground plane. In my case, I expect that corona discharge will occur briefly after the HV generator is turned on, but ...
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3answers
48 views

RC Circuits- Charge and Energy

It takes longer for the charge in an RC circuit to fall down to half its initial value than for the stored energy. Why?
1
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1answer
40 views

Gauss's Law on Parallel Conducting Plates

I have a question regarding the application of Gauss's law to find the E-fields produced by two parallel conducting plates. My textbook (Halliday and Resnick 9e) states that there is no E-field above ...
1
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1answer
43 views

Why is neper frequency called a frequency?

In the context of complex frequency of RLC circuits, the real part is called neper frequency, according to units it's understandable that it has 1/s as the unit which is same as frequency but what is ...
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0answers
10 views

Passive heat shield possible to stabilize performance of high tempetature range supercapacitors on Moon?

On the Moon surface, the temperature can oscillate between -160°C and +130 °C. As I can see, there are high remperature range supercapacitors available to work between -55°C and +200°C. Research ...
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2answers
45 views

Heat developed in a circuit

Suppose I have a simple circuit with capacitors, a battery and a key. There Is a change in energy stored in capacitors when the key is closed. How will I find the heat developed in the system? Is the ...
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0answers
19 views

A relationship between parallel plate capcatior's capacitance & it's spacing distance

In my experiment class, I measured a curve between the parallel plate capacitor's capacitance and it's spacing distance. But the result is not very similar to expectation - despite the spacing ...
0
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1answer
30 views

How does charge movement vary between insulators and conductors?

I've been reading A Student's Guide to Maxwell's Equations by Daniel Fleisch, and he states: in nonconducting materials (called "insulators" or "dielectrics"), charge does not move freely, but may ...
0
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1answer
18 views

Rates of charging in an RC circuit when components are partly charged initially

Just to be sure of my reasoning I am describing a simplified version of my problem Two capacitors of capacitance $C_1$ and $C_2$ are connected in series to a battery of emf $V$ volts having some ...
0
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3answers
72 views

Energy of parallel plate capacitor

Energy of parallel plate capacitor is defined as $$\frac{CV^2}{2}$$ where V is the potential difference between plates, but shouldnt we need to find the potential energy of each plate due to charge ...
0
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2answers
46 views

Discrepancy in capacitor

Let a capacitor be connected to a battery in a circuit. The battery does work worth $CV^2$ but the capacitor stores only half that amount... We say the other half went away as heat, but how do we ...
0
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1answer
50 views

How to derive the $\Delta$-$Y$ formula for capacitors? [closed]

So, I've found a youtube video that first derives the formula for the resistors and then says the capacitance is the resistance^(-1). I was wondering if that would be the right approach.
0
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1answer
151 views

Magnetic field in a capacitor

If in a flat capacitor, formed by two circular armatures of radius $R$, placed at a distance $d$, where $R$ and $d$ are expressed in metres (m), a variable potential difference is applied to the ...
0
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1answer
45 views

Change in potential energy of a parallel plate capacitor as a dielectric slab is moved in the space between plates

I was doing this question: If a parallel plate capacitor made of square plates of side L and separation D is connected to voltage source V. And then a dielectric slab of width D is introduced ...
51
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16answers
4k views

Intuitively, why does putting capacitors in series decrease the equivalent capacitance?

Can someone please explain, intuitively (without any formula, I understand the formulas), why the equivalent capacitance of capacitors in series is less than the any individual capacitor's capacitance?...
1
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2answers
55 views

How does a Leyden Jar work?

When electricity goes inside the Leyden jar, the inside of the jar is negatively charged. Then the aluminum foil on the outer layer of the jar is positively charged. Does the inside of the jar want to ...
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5answers
151 views

Capacitance for infinitely large plates

Let's say you have two infinitely large plates. I understand the formulas for capacitance. What I don't understand is the intuition behind the fact that when you increase the distance between the ...
0
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1answer
71 views

Capacitance and it's intuitive explanation

I was looking for an intuitive explanation for the capacitance between two plates, couldn't find any suitable though. So I tried to figure it out myself and I am wondering if it is correct. ...
0
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1answer
21 views

Polarized Vs Non-Polarized Capacitors

I am wondering what makes a polarized capacitor physically different than a non-polarized capacitor. I am aware they are functionally different. I understand the physics of a non-polarized capacitor, ...
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2answers
64 views

RC circuit series and parallel [closed]

R and 2R are in parallel. 4R and 3R are in parallel. I dont know where to go after calculating the the parallel Rs. Do you become in series? If so, how? It is right after the switch is closed. So ...
0
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0answers
21 views

Capacitance of two parallel cylinders of finite length

I've got some big troubles calculating the capacitance of two parallel cylinders of finite length. If the cylinders are infinite everything is fine but I need an excat solution or at least a good ...
0
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1answer
27 views

How can a charged hollow sphere induce charge on a neutral conducting sphere kept inside it?

In case of a charged conducting hollow sphere charge resides on the surface and the field is radially outwards or inwards depending on the charge.Due to the symmetric consideration field inside the ...
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6answers
82 views

Telling if Capacitors are in Parallel or Series

So C1 and C2 are in series. But if each one is placed in red boxes, they are in parallel? It's confusing going jumping between current, capacitors, and resistance. For me it's kinda confusing ...
2
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4answers
96 views

Internal resistance and Instantaneous current?

Okay, this would probably seem a pretty basic doubt but I can't understand this thing. I know that when the current is not flowing in the battery the voltage across the terminals is the emf of the ...
0
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1answer
28 views

Question on capacitance between two parallel cylinders

We are asked to prove that the capacitance of two infinitely long uniformly charged conductors with coaxial cylindrical surfaces is given by \begin{equation} C= \dfrac{2\pi\epsilon_0L}{\mathrm{ln}\...
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0answers
25 views

What is the Potential difference in $C_1$? [duplicate]

I can not seem to figure this out. My try so far: put C2 and C4 as C' by parallel put C' and C1 as C'' by series Finally, Put C'' and C3 and C5 as Ct by series find Qt by Qt=Ct*V after finding the ...
0
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1answer
17 views

Electric field in capacitor arrangement with different dielectric media

Please consider the following arrangement of infinitely extended charged plates. In z-direction the system also extends to infinity. The charged plate in the middle of the figure is 2x negatively ...