All Questions
Tagged with electricity capacitance
175 questions
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Feasibility of Supercapacitor Design Using Etched Brass-Coated Copper Wires [closed]
I'm working on designing a supercapacitor and would appreciate any insights into its feasibility and potential challenges.
Design Overview:
My plan involves creating multi-layer coils where the anode ...
0
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1
answer
49
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Effect of electric charge on human body
I was reading some other questions when I came up with this.
People are often warned about the danger of electric currents passing through the body. Is charging the human body with a small current ...
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-1
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1
answer
40
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What will Electric field be when the charge on negative side of Capacitor is changed? [closed]
One of the two parallel metallic plates is uniformly charged with charge $+q$, and the other one is charged with charge $-q$, the electric field between them is $E$. When the negatively charged plate ...
1
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0
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17
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Is there simple harmonic motion when a dielectric longer than the capacitor is inserted into the capacitor? [duplicate]
I’m trying to understand the mechanics of a dielectric being inserted into a parallel-plate capacitor. Suppose I have a parallel-plate capacitor with plate separation d and a dielectric slab of length ...
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1
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46
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Why do different ways of calculating the new capacitance of a capacitor after being partially filled with dialectric yield different results? [duplicate]
I have encountered this problem that stumped me and my colleagues. It is expected to be solved by Physics II students. I tried asking some faculty members but to no avail.
An air-filled parallel ...
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54
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Why aren't "composite" capacitors a thing?
Recently I started researching more about capacitors and I wondered why it's not possible to put a layer with a high electric breakdown strength between two layers of high permittivity? Wouldn't you ...
2
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0
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42
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What if two plates charged with different charges are placed face to face?
I'm asking this question because I can't solve it even if I ask a lot of smart people. (Please understand that I don't speak smoothly because I use a translator. I'm korean student..)
In the next ...
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91
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Why does the current flow through a wire if the wire is an equipotential surface? [duplicate]
From what I know, current flows across two points only if there is some potential difference across those two points. If that is the case, why does the current flow through a wire then?
See the ...
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83
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How to describe the real world rise of a liquid into a capacitor?
Known from a Capacitor in a dielectric fluid a bipolar Liquid is rising into a capacitor:
To now actually describe the rise Δ𝑥 of the liquid I consider the equilibrium of forces.
The Forces are: &...
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2
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527
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Salty water impedance vs. frequency
I was experimenting with measuring the dielectric constant of tap-water and also water with salt added.
The measurement was done by submerging a simple cylinder capacitor into a container with the ...
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3
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99
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How do we correctly handle a power source and a capacitor in parallel?
$\newcommand{\d}{\mathrm{d}}$
Here $V$ is an alternating supply, $R$ is a fixed resistor and $C$ is an capacitor. All components, including the diode, are ideal. Say $V(t)=V_\max\sin\omega t$ - with ...
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2
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60
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Current in a two capacitors system in parrallel
I solved this question and I got the values of charges on capacitors in figure B. But my question is charge on capacitors is getting redistributed,but how is it possible when potential difference ...
1
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0
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135
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Capacitance of a System of Two Spheres
To explain more clearly, I am looking for how one would derive an expression for the capacitance of a system which consists of two conducting spheres of radius $a$ separated by a distance $d>2a$. I ...
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3
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121
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Why won't the bulb light? [closed]
Here's what the marking scheme says: "Capacitor gets charged first and acts as an insulator/blocks current".
However, electrons flow from negative to positive, so shouldn't the electrons ...
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1
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57
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Charge in a capacitor circuit [closed]
Firstly switch K is being closed and that one capacitor is being fully charged. Then the switch K is being opened again. What will be the difference of total charge in the system before and after ...
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1
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1
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292
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Confusion involving the energy stored on a capacitor
In A-level physics, one is told that:
The energy stored in a capacitor with charge $Q$, capacitance $C$ and voltage across the plates $V$ is: $$\frac{1}{2}\frac{Q^2}{C}=\frac{1}{2}QV=\frac{1}{2}CV^2$$...
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4
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152
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Can this capacitor cycle generate electricity?
Imagine a capacitor where the distance between charged plates can be changed. It is connected to a circuit such that the following cycle is possible:
Capacitor is connected.
Plates are charged.
...
2
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2
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234
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Why can't I observe a voltage between two capacitor plates when only one of the plates is connected to a battery?
Let's say I have a battery and a capacitor that is neutral. Now I connect the battery positive terminal to only one plate of the capacitor. From what I know, there is a potential difference between ...
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2
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Discharging capacitor: Series vs Parallel
Pretty basic stuff, but to be honest I haven't found a circuit diagram showing a capacitor discharging in parallel.
The only scheme I can come up with is shown here: $\color{gray}{\textbf{[ Edited ]}}$...
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75
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Charges on conducting shell with a conducting sphere inside it
If I have a spherical capacitor which is composed of a conducting sphere surrounded by a conducting shell and the space between them is filled with a dielectric , I assumed that the charge on the ...
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1
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75
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What is electric permitivitty?
I have read 10 different explanations for this in 10 minutes. By definition, to permit means to allow something, but some sites say that it is actually how much a material resists the electric field?
...
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2
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348
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Potential energy of parallel plate capacitor
I am trying to calculate the electrostrictive strain S on a parallel plate capacitor.
For that, I use Young's modulus Y and the formula
$$S = \frac{F}{AY}$$
Since the area A and the Young's modulus ...
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3
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286
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How can I increase the discharge time for capacitor?
Actually I was trying to make a capacitor and used Aluminium foil and paper to do this. Then i went for testing it. But I found that the capacitor was not working. Firstly I charged it with a battery ...
user316791
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3
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I have trouble understanding why two different capacitors should have the same amount of charge on each side of a circuit
There is a rhombus with four different capacitors. There's a voltage between the point $a$ and the point $b$, but there is no voltage between the point $c$ and the point $d$. Apparently, assuming that ...
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How can we take dielectric medium kept between the capacitor plates as capacitors in series and solve for effective capacitance?
My book says that the charge induced on the dielectric slab kept between the parallel plates is given $Qp=Q(1-1/K)$ where $K$ is the dielectric constant and $Q$ is the charge on the capacitor.
I have ...
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3
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668
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Why does the voltage goes away in my leyden jar?
This question is similar to this one in the sense that I have my amateurish Leyden jar and I'm supplying ~7.5v from 5 batteries (~1.5v each) in series.
Some details and facts after experimenting:
...
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1
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1
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67
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Would electricity be able to make a gamma ray?
I read that lightning creates gamma rays, but i'm not sure if it would be possible to have a capacitor that powerful to make a gamma ray.
If this is possible, how efficient would such a process be?
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Are Idealized Transformers Realizable?
Since parasitic capacitance in an inductor is always in parallel with its inductance, would this effectively become analogous to magnetic remanence exhibited within rebars (made from carbon steel) ...
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86
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Does making a conductor spiky increase its capacitance?
I'm thinking of the proofs for "charge accumulation at the points of a spiky conductor" e.g. https://www.feynmanlectures.caltech.edu/II_06.html 6-11
If charge accumulates at sharp edges, I'm ...
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Capacitors and Kirchoff's Voltage Law
If we connect capacitor to voltage source, its voltage will be equal to voltage of the source when capacitor is fully charged due to Kirchoff's voltage law and no current will flow in a circuit any ...
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Changing battery of capacitor
Say a capacitor is charged to its fullest capacity by a battery of $5\rm\ V$ and capacitance is $2\rm\ C/V$. The battery is now replaced by a $K\rm\ Volts$ voltage one. How will the current flow? Note ...
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Determine the change of charge in both capacitors
I have the following circuit
The switch has been open for a long time, and both capacitors are fully charged. After that, the switch is closed and the circuit is broken. I need to determine the ...
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Charging a single plate of a capacitor does not work
I charged a 100nF capacitor with 12V with a battery, then i disconnect the battery from the capacitor and connect the positive side of the capacitor to ground (which is an electron source) ...
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2
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86
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Is battery a capacitor that's being continuously charged?
Is it correct to say that a battery is like a capacitor which keeps being charged?
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What would an optimally designed (maximising the capacitance) capacitor look like? [closed]
I've just finished the chapter about capacitors on my textbook, and I have a question. So, there are problems in my textbook where the capacitance of different arrangements of charged surfaces is ...
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2
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643
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What's the electric field inside a capacitor with AC current?
In DC-circuits the Electric field can be easily calculated under the conditions the field is homogeneous: $U = \int E \,\mathrm{ds} = E\,d$. Now I wonder what if you apply an alternating Voltage $U(t)...
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378
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Charging capacitor, Relaxation time - obtained experimentally and theoretically [closed]
In the shown circuit, I was measuring how the voltage on capacitor $V_C$ changes with time. The theory says that $V_C(t) = V_T(1- e^{-t/R_1C})$, where $V_T$ is voltage on battery. If I plot my ...
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3
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Why does the voltage measured across a capacitor increase with time [closed]
The voltage measured across a capacitor increases over time as current flows through the circuit because more charge is accumulated. I thought however that since voltage is defined as energy/coulomb, ...
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1
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What is the difference between the two formulas for each of resistance and capacitance?
Resistance and capacitance (of parallel plate capacitors) both have two formulas for them: $R=V/I$ and $R=ρL/A$ for resistance, and $C=Q/V$ and $C=ƐA/d$ for capacitance. For any given resistor and ...
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3
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Why voltage is not the same for the capacitors in series?
In this picture, there are two capacitors C1 and C2 joined in series and connected to a battery. We know there are two terminals in a battery, a positive terminal and a negative terminal.
The ...
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1
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Why is my approach to this problem about charging an uncharged capacitor with a charged capacitor wrong? [closed]
This is the above mentioned problem :
Using a battery a10 pF capacitor is charged to 50V and then the battery is removed. After
that, a second uncharged capacitor is connected to the first capacitor ...
0
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1
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150
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Analog of harmonic oscillation to electrical circuit
Equation of a damped harmonic oscillator under varying force $F$ is:
$$
m\dfrac{\mathrm{d}^2 x}{\mathrm{d}t^2}+\gamma m\dfrac{\mathrm{d}x}{\mathrm{d}t}+Kx=F
$$
And the electric analog to this is:
$$
L\...
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288
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How do you set up Kirchhoff's loop rule for a circuit with a charged capacitor, uncharged capacitor, and resistor?
If I connect a circuit with charged capacitor that has charge $q$ to an uncharged capacitor and resistor, how would I set up a differential equation that can be used to find the time constant? I know ...
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1
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379
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Does discharging of capacitor create sound?
Today I found a wierd thing that as I removed the pin of the echo dot
And after this I removed the adapter from the power supply and found a wierd buzz sound coming from the adapter but as I ...
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2
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76
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Electrical shock with a live wire
If a person were to touch a live wire while on an insulated platform, the resistance shoukd prevent any current flow. However, I have read that there is capacitative coupling voltage. I have studied ...
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77
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When a capacitor discharges in a simple RC circuit, is it treated as an active component?
While deriving expression for the voltage across capacitor in a discharging RC circuit, I stumbled across whether I should treat the capacitor as an active or a passive component(To properly apply the ...
0
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2
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669
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Why does the capacitor charge through a resistor?
I was working on a question where there was a circuit and the switch was open, there was one capacitor and one resistor. It said: immediately after the switch is closed, what is the current in the ...
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1
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1k
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Capacitors and how electrons flow given the electric field direction
My question is given that a capacitor creates a two charged sides, by the electrons jumping from one plate to another thereby making one having an excess of electrons making it negative and the other ...
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2
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129
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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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2
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1k
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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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