The ability of an object to store electric charge.

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How are current and voltage out of phase in capacitive circuit? [duplicate]

Possible Duplicate: Physical explanation for capacitive circuit We say that in capacitive circuit, the voltage and current are out of phase. Current is 90 (degrees) ahead of voltage. What ...
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106 views

Magnetic force on capacitor

I have this problem: I have a capacitor formed by two parallel square-shaped plates, of side $a$, and with distance $d$ between them. They're asking me out of other things, the magnetic force as a ...
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182 views

Is it possible to charge a capacitor to any potential? Does it depend on the dielectric placed between them?

Is it possible to charge a capacitor to any potential? Does it depend on the dielectric placed between them? Or, are there other factors affecting it?
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What defines the maximum charge a capacitor can store?

The formula for a capacitor discharging is $Q=Q_0e^{-\frac{t}{RC}}$ Where $Q_0$ is the maximum charge. But what property defines the maximum charge a capacitor can store? If it depends on ...
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What is the role of battery across a Parallel plate capacitor having equal charge?

Each plate of a parallel plate capacitor has a charge $q$ on it. The capacitor is now connected to a battery. Now, which of the following options are correct? a) The facing surfaces of the ...
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410 views

Explanation of NMOS processes

Gate (poly-Si + $SiO_2$) and $p^{-}$ silicon operate as capacitors. But how are voltages and charges applied? In order for inversion to occur, there should be charges formed in poly-Si, right? How ...
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Capacitance per unit area and CMOS case

In a modern 0.35μm CMOS processor, the gate oxide thickness is around 80Å = 8nm. This gives us a capacitance per unit area of $430nF/cm^2$ I am not getting how one gets this capacitance per unit ...
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Capacitor charging and discharging

I have a conceptual question. The circuit is shown below. Let us assume that the capacitor shown in the figure is of 2.2 micro-farads having rated level of 5 volts and we decide to charge it up to 2 ...
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637 views

Why does a capacitor discharge a percentage of the original energy in the same time?

If I charge a capacitor ($220\mu{F}$) using a 6V battery, and then measure the time it takes to discharge 90% of the initial energy over a resistor (${100k}\Omega$), and then charge the same capacitor ...
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739 views

Physical explanation for capacitive circuit

In capacitive circuit, the voltage and current are out of phase. the current leads the voltage by 90 degrees. this can be explained by these two equations: $$V = V_{\max} \sin \omega t$$ $$I = ...
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227 views

Charging using a CRT TV set

I was doing an experiment with my CRT TV where I put aluminum foil on the screen wire it to a can and open the TV and a ring between 2 can will swing if I ground the other can. ...
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If we charge a capacitor can we discharge it into a battery?

I have read that we can charge a capacitor using a battery, but can the vice versa happen? My project needs to show a battery being charged through a fully charged capacitor.
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414 views

Charge on capacitor plates in series combination?

Suppose 2 capacitors are connected in series, the plates connected to the battery terminals receive charges $+q$ and $-q$, and the isolated plates in the combination receive equal and opposite charges ...
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91 views

Unrolling electrolytic capacitors

If I take an electrolytic capacitor, remove the aluminium casing, unroll the foil/ electrolyte-soaked paper, if charged, will it still work? And what if I took of the cathode foil and wrapped the ...
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1answer
387 views

Will I recieve a shock if I charged a capacitor then i touch the 2 poles in same time?

What happens if I charged a capacitor then i touch the 2 poles in same time?
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1answer
878 views

Calculating the electric relative permittivity of fluid or medium?

I'm unsure of how to calculate the permittivity of a fluid. Permittivity differs from one fluid to another: $$\varepsilon=\varepsilon_r\varepsilon_0$$ Since it is an electrical property combined ...
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78 views

Can we transfer the charge on a plate of a capacitor elsewhere?

I know it is hard , but can we transfer the charge on a capacitor plate elsewhere?
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77 views

Charge of an electrolytic capacitors

I can't understand the electrolytic capacitors, when a capacitor has a capacitance of 100 microfarads, does that mean that when it is charged with 100 volts will the charge of the plate be 0.01 ...
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1k views

Poynting vector of a wire between capacitors

A capacitor made of two circular plates of radius $L$ separated by $d$, initially the plates carry $\pm$ Q charge. Then a wire of resistance R is placed between them, how do I go about deriving a ...
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3answers
633 views

Find Inductance in a Coil

Question: An inductive coil has an internal resistance of 20 $\Omega$. When an AC Voltage source with a frequency of 100 Hz is connected to the coil, the current lags the voltage by 30 degrees. What ...
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310 views

Will the plates of a parallel plates capacitor keep its charge after being charged then seperated from the non- conductor?

If i had 3 plates 2 metals and 1 glass .I put them together to form a basic parallel plates capacitor. After charging it and approaching it to an electroscope nothing happened that's because ...
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341 views

Effect of charges near a parallel plate capacitor

If I charge a parallel plate capacitor and I insert a charged body near one of the plates will there be any interactions like attraction or repulsion? What if I disconnect the battery?
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814 views

Capacitance of two almost-touching hemispheres

This capacitor is composed of two half spherical shelled conductors both with radius $r$. There is a very small space between the two parts seeing to that no charge will exchange between them. So ...
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Why is water not used as a dielectric in the condenser?

The dielectric constant of water is very high. Then why is it not used as a dielectric in the condenser?
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231 views

Energy in electric field

I'm having some trouble understanding a homework question and would appreciate some help. The question is as follows: Jenny charges a capacitor with the help of a battery. She then removes the ...
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3answers
544 views

Change in attraction of charged bodies

If I insert a piece of glass between two objects carrying different charges, would they still attract? If they attract, does the piece of glass affect the force of attraction and is there any formula ...
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1answer
1k views

Breakdown voltage of a dielectric

I know that a capacitor with a dielectric can operate normally up till a certain voltage (AFAIK called breakdown voltage) which depends on the strength of the dielectric placed between the plates. ...
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4answers
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A problem of missing energy when charging a second capacitor

A capacitor is charged. It is then connected to an identical uncharged capacitor using superconducting wires. Each capacitor has 1/2 the charge as the original, so 1/4 the energy - so we only have 1/2 ...
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Is there a deep reason why springs combine like capacitors?

I was solving a practice Physics GRE and there was a question about springs connected in series and parallel. I was too lazy to derive the way the spring constants add in each case. But I knew how ...
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1answer
854 views

Calculating capacitance of integral PCB components

I posted this question originally with Electrical Engineering Stack Exchange but nobody seems to know the answer. So I thought a physicist might find the question more approachable. Formulas for ...
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2answers
623 views

Proof of charge existence on a grounded conductor

A question regarding the existence of charge on grounded conductors is confusing me. Could there be charge on a grounded conductor? How does this not contradict Gauss's Law? Since every conductor ...
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3answers
2k views

When I connect two charged capacitors side by side, what will be the voltage across them?

Say, I have two charged capacitors, one 3mF and one 2mF. The voltage across them are 20V and 30V respectively. Now if I connect the two capacitors side by side as shown below, what will be the voltage ...
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4answers
5k views

Will a charged capacitor discharge if one lead is connected to ground?

If I charge a capacitor and connect one lead to ground keeping the other lead floating, will the capacitor discharge ? ...
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4answers
2k views

Why does it seem that the potential difference dependence of capacitance and total energy stored in a parallel-plate capacitor are contradictory?

Consider a parallel-plate capacitor. Charge is stored physically on electrodes ("plates") which are flat and parallel to one another. If one electrode has charge $+Q$ and the other electrode has ...
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3answers
858 views

Parallel-plate capacitor

I'm trying to grasp parallel-plate capacitors in a class of electromagnetic field theory. My book leaves out a lot and I couldn't figure it out from what I found on Google. The book's procedure is ...
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What is the difference between a battery and a charged capacitor?

What is the difference between a battery and a charged capacitor? I can see lot of similarities between capacitor and battery. In both these charges are separated and When not connected in a circuit ...
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4answers
2k views

Parallel or series connection?

Are C1, C2 and C3 connected in parallel, or C2, C3 in parallel and C1 in series with C23? Btw it appeared as a question in the basic physics Albanian A-levels yesterday. You had to find the ...
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2answers
86 views

Permitivity $\mathcal{E}$ as a function of Voltage across a medium

What I wanted to Know was is there a change in Dielectric Permitivity constant as the voltage increases. My question arose from the fact that for a breakdown voltage to be reached the Permitivity ...
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3answers
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Distorted colors of Google StreetView photographs near electric power lines

This is a followup to my question: Cyclist's electrical tingling under power lines Some users presented a convincing picture that the electric shocks under power lines are primarily from the ...
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3answers
11k views

How can I theoretically describe the potential between two capacitors in series?

Suppose to have two capacitors in series: The voltage in the middle point will be: $$ V_X = V_1 \frac{C_1}{C_1+C_2} $$ How can this be explained? It's been asked in electronics, and explained in ...
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2answers
2k views

Charge distribution on a plate of Capacitor with Dielectrics .

I had this Homework Problem with a capacitor (parallel plate) that has a group of 3 dielectrics between it like so : Now We were asked to find the equivalent capacitance and the distance of ...
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2answers
3k views

RC circuit theory and voltage in the capacitor vs Ohm's Law

Consider a simple series RC circuit at steady state (capacitor is full). I've been told that once the capacitor is full we can literally "cut" the circuit because no current can flow. That ...
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1answer
467 views

Dielectric in a parallel plate capacitor

Uniform charge: each atom has charge $q$. Magnitude of dipole moment is $q s$, where $s$ is the distance the nucleus is shifted. According to my notes, the charge on the surface of a dielectric in ...
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1answer
768 views

Why is this charge distribution in correct? Capacitors in parallel and series

Please consider the circuit diagram below, in particular, look at the capacitors enclosed by the green loop. *Note that the green loop and the (+) and (-) charges on the plates were drawn by me, ...
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3answers
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What's the right way to calculate charge on a capacitor?

How much charge is on each plate of a 4.00-F capacitor when it is connected to a 12.0-V battery? I said 2.4 x 10^-5 C because there are two plates of a parallel plate capacitor. But the key said only ...
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2answers
719 views

Capacitors in series

I need some explanations on the green underlined sentences. 1) "Must continue to have zero net charge..." What if the $\ C_2$ had +2Q on the left plate and -Q its right plate? The net charge ...
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1answer
823 views

Potential difference between conductors

Reading some books there is something that i don't understand. Is the capacitors topics when they name a potential difference between conductors. As i know, Potential difference is the difference in ...
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2answers
205 views

Is it true that capacitors closer to a power source charges quicker and gets priority?

Let's say I hook two capacitor in a parallel circuit with a voltage source. Would the capacitor closer to the battery be charged up first? Because when the voltage excites and draws electrons from the ...
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3answers
567 views

Is this really how a capacitor works? Why doesn't it behave like a resistor?

My book says a capacitor is two conducts being connected by an insulator. Now let's take a parallel plate capacitor to simplify the problem I have. Suppose I got two parallel plate capacitor in ...