Questions tagged [capacitance]
The ability of an object to store electric charge.
1,128
questions
2
votes
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 ...
0
votes
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
votes
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 ...
-1
votes
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
votes
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
votes
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$$V=-...
3
votes
3answers
81 views
Why don't capacitors hold charges on the outer walls of the plates?
Suppose I have two metal plates in a vacuum and I give this system some electric charge,the charge would distribute itself according to Gauss law on both the inner and outer walls of both plates...but ...
0
votes
0answers
18 views
Force of attraction in capacitor [duplicate]
In a question, it was asked the force of attraction between the plates of a parallel plate capacitor.
and it was solved as
$$\frac{(1)(C)(V^2)}{2}=(F)(d)$$
$$F=\frac{(1)(C)(V^2)}{(2)(d)}$$
and I ...
-3
votes
0answers
43 views
I got the answer but I suppose I did not understand the question very well [duplicate]
See as per the question, The Inductor pretty much will induce emf due to magnetic field and not due to other coil/current nearby. Thus I used $E= - d(phi(t))/dt$ as the induced emf.
Then using (...
0
votes
1answer
22 views
Why are the times at which max rate occurs different for the energy of a capacitor and the battery
When charging a capacitor the rate at which the battery provides energy is maximum at $t=0$ but the time at which the rate of increase in the energy of a capacitor is maximum is $t=CR\ln(2)$ (where $C$...
5
votes
3answers
339 views
What happens when electrons reach the battery?
We have a capacitor which is connected to a voltage source. The top plate of the capacitor is connected to the positive terminal of the source. Therefore, electrons go from the top plate to the ...
0
votes
1answer
39 views
Doubt in the derivation of Gauss's law in dielectrics
so in the 2nd page,when the dielectric material is introduced the gauss's law becomes $$\oint _ { S } \vec { E } \cdot \vec { d S } = \frac { ( q - q _ { i } ) } { \epsilon _ { 0 } }$$.But my ...
-3
votes
0answers
43 views
How is the 4th option related to the question? [closed]
I cant seem to understand the 4th option at all. How is it related to the question? Can you please help?
0
votes
1answer
44 views
Force in an isolated capacitor when a dielectric slab is introduced [closed]
my question is about capacitance:
a dielectric slab is inserted between the plates of an isolated capacitor. The force between the plates will remain unchanged. how?
I mean the knowledge I had gained ...
4
votes
0answers
67 views
Voltage propagation along a wire [closed]
Let's say you have a wire connected to a device that you can switch between high-voltage and ground voltage. The wire is not connected to anything on the other end. You're observing the voltage in two ...
1
vote
0answers
39 views
Why am I getting two different expressions for capacitance? [duplicate]
The question is:
A capacitor of capacitance C1 is connected to a battery of potential V0. The battery is then disconnected and a second capacitor of capacitance C2 is connected to the first ...
-2
votes
2answers
37 views
Capacitors connected in parallel with a switch attached [closed]
What does it mean when they say capacitor reaching equilibrium?
3
votes
2answers
129 views
Circuit - solve Kirchhoff's laws with determinant?
Here is an exercise from my textbook.
]1
At first I solve it by using Kirchhoff's laws directly and using complex impendance:
$$U_{in}=\frac{1}{Cs}(i_1-i_2)+i_1R_1$$
$$0=R_2i_2+\frac{1}{Cs}i_2+\frac{...
0
votes
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
votes
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
votes
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 ...
0
votes
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
votes
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
votes
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 ...
1
vote
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
vote
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
vote
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 ...
0
votes
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 ...
0
votes
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 ...
1
vote
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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
vote
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 ...
1
vote
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
votes
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
votes
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, ...
-1
votes
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
votes
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
votes
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 ...
0
votes
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
votes
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
votes
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}\...
0
votes
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
votes
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 ...
