The ability of an object to store electric charge.

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What happens in a circuit, when the wire and the battery are superconducting. And shorted

When a wire with no resistance is connected to the terminals of an ideal battery, will a current exist in the circuit? If a capacitor is added to the circuit, will it be charged by the battery or will ...
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126 views

What is the correct way to take out equivalent capacitance here?

So here I have a capacitor with two plates , one positively charged and one negatively, as shown in the figure. Now the material between them is $k_1$ for thickness d/2 and $k_2$ for the other d/2. ...
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1answer
1k views

Three-plate capacitor [closed]

What is the total capacitance of this capacitor? Is it analogous to the case of inserting a plate into a capacitor (essentially creating two capacitors in series)?
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1answer
3k views

Wheatstone bridge Capacitor,Dead Capacitor [closed]

I want to know that if in a Wheatstone Bridge ,that is made of capacitors only we have this condition $c_1c_3=c_2c_4$. The $c_5$ capacitor would be dead and it's voltage would be zero? Actually I am ...
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1answer
334 views

Kirchoff's rules and RC circuits [closed]

You can view the image bigger: http://i.stack.imgur.com/4moUP.png I'm studying RC circuits and I can't understand the part when we use Kirchoff's rule. When working with batteries, when we're going ...
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1answer
745 views

What is the capacitance of parallel plate capacitor with different electrode material?

What is the capacitance of parallel plate capacitor with different electrode material? The capacitance of parallel plate capacitor depends on dielectric material, surface area, and separation between ...
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2answers
2k views

Energy Stored in a Capacitor with and without Dielectric

I have seen the equation $V = \frac {V_0}{K}$, but also the equation $V=\frac{1}{2}CV^2$. The values of C and V increase in the same linear ration with K (because $C=KC_0$). However, as the energy ...
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Simultaneous Charging and Discharging Capacitor

sorry if I sound little noobish. Though I have a fairly good understanding of physics, I sometimes don't understand the electrical aspects. Say there is a capacitor. This capacitor is expected to act ...
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1answer
77 views

Charging a capacitor

Below is an excerpt from a physics textbook: One common way to charge a capacitor is to connect these two wires to opposite terminals of a battery. Once the charges $Q$ and $-Q$ are established on ...
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1answer
370 views

Capacitor with dielectric between the plates

Let's assume we have a capacitor of capacitance $C$ and potential difference $U$. After charging it we disconnect it. Then we put a dielectric between the plates. I know that capacitance will increase ...
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2answers
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capacitor in ac and dc circuits

In a dc circuit work done by battery=QV while energy stored in capacitor =(QV)/2 loss in energy=(QV)/2 While a capacitor in ac circuit has a no power loss.why is it so? Shouldn't heat be lost in ac ...
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3answers
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Why do both plates of a capacitor have the same charge?

How do we know that both plates of a capacitor have the same charge? You could argue conservation of charge, but I don't see how conservation of charge implies the charge on both plates is the same. ...
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91 views

Capacitor in series?

Say you have two charged capacitors in series. Zoom in on one capacitor. For this specific capacitor, the charge on the two plates will be the same in magnitude, according to my textbook. My teacher ...
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4answers
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Is a capacitor in an open circuit charged?

Say I have a circuit consisting of a battery, a wire, an open switch, and a capacitor. The circuit is open since the switch is open. My book says that the capacitor will only be charged when the ...
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1answer
1k views

How do you solve Laplace's equation for a parallel plate capacitor?

I would like to find the analytic solution to the problem of two plates of opposite electric potential. I have already solved this numerically as shown in the picture below. I'm also wondering what ...
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4answers
2k views

What is the current of a capacitor when the derivative of voltage is undefined?

This is from the textbook I am reading: I know this equation for capacitors: $$i=C\cdot \frac { dv }{ dt }$$ Here is my question: how can diagram (a) be allowed if the derivative of the voltage ...
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1answer
191 views

Capacitance of bodies with different charge [duplicate]

How does one calculate the capacitance of two bodies with different charges? I was looking at coefficients of potential, but they don't seem helpful.
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3answers
75 views

Capacitance of Parallel Plates

For Parallel Plate Capacitors, I was wondering why, in the derivation, they set charge to $Q$, when there is a net charge of zero? I know it wouldn't be very helpful to use zero, but if the definition ...
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3answers
5k views

Why isn't the electrical field between two parallel conducting plates quadrupled?

For the sake of clarity and brevity, here is the description from my textbook (Halliday & Resnick 9th): This description states that the electric field is doubled. I am seriously confused. When ...
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1answer
360 views

Charging the plates before making the capacitor

Basically, a simple capacitor will consist of 2 plates and a dielectric material between them, what if i took 2 plates, charged one with a +ve charge and the other with equal -ve charge, then i put ...
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3answers
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Capacitor with different charges on each plate

I am confused as to whether/how capacitance changes when each plate has a different charge. For example, consider a coaxial cable and put $20Q$ on the outer cable, and $-Q$ on the inner. Or how about ...
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3answers
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Electric field intensity in a dielectric inside a capacitor

In the question A parallel plate capacitor is charged from a cell and then isolated from it. A dielectric slab of dielectric constant $K$ is now introduced in the left half region between the ...
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1answer
104 views

How to get a function for the voltage across a capacitor connected to an AC voltage source? [closed]

I am looking for the way of obtaining a solution for $V_{c}$ ,as a function of $t$ depending of $\omega$, of the following differential equation related to an electrical circuit involving a low-pass ...
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0answers
396 views

Absolute permittivity and permeability of free space

I'm reading about the propagation of EM waves in vacuum. We define the wave equation using two constants: $\epsilon_0$ and $\mu_0$. Of course they are absolute permittivity and absolute permeability ...
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1answer
1k views

How do capacitors work?

Say you have a battery, with a wire connecting the negative and positive terminal. Initially, (the transient state) the electric field is not uniform and is perpendicular to the surface of the cross ...
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3answers
118 views

Are these assumptions correct?

Is it true:From equation $C=Q/V$ 1)If Potential difference is kept constant $C \propto Q$ 2)If charge is kept constant $C \propto 1/V$ Then if 2nd is true I do have a question: Don't we say that ...
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207 views

Why change in Capacitance?

I do know it that the overall capacitance decreases if two or more capacitors are connected in series,but do not understand why? I do understand it mathematically but don't get the physics behind it.
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19 views

Resistor connections [duplicate]

I can't figure out what kind of connection it would be if i put resistors like this Can someone please explain how they are connected, like is R1 and R2 in series and R4 and R5 in series and then I ...
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Does there exist a single plate capacitor(conductor)?

Does there exist a single plate capacitor(conductor)? if yes How will you define the capacitance and potential(difference) of such conductor?
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1answer
518 views

Parallel Plate Capacitors

I was wondering what would happen to capacitance if the plates are not parallel (above/below each other) or if the plates are not the same size. Thanks.
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RLC circuit, turning off the voltage source

An RLC circuit (pictured above) is governed by two equations: \begin{align} -iR &= -L \frac{dj}{dt} = \frac{q}{C}+V(t) \\ \frac{dq}{dt} &= i+j \, . \end{align} $q$ satisfies the equation $$\...
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2answers
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Capacitors in series: Why is the equivalent charge the same as the individual charges

Consider two parallel-plate capacitors $C_1, C_2$ in series. For the "equivalent" circuit, clearly $$ Q_{equiv} = C_{equiv}V$$ should hold, where V is the total voltage drop between input and ...
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157 views

Capacitors in series?

Capacitors in series have identical charges. We can explain how the capacitors end up with identical charge by following a chain reaction of events, in which the charging of each capacitor causes the ...
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172 views

Charging a Capacitor?

How is the charge +q given to the one plate to the capacitor with the help of a battery, does the battery remove electrons from the plate and +ve charge gets accumulated on one plate?Does it? And one ...
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Electric potential and maximum charge on a conductor

Does increasing the amount of electric charge on a conductor cause an increase in its electric potential to a point at which it becomes maximum; where it can hold no more extra charge? Is it true? ...
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Are there analogs to resistance, inductance, capacitance, and memristance connecting the weak force to electromagnetism?

A question was asked over at EE.SE recently which I tried to answer, but much of my answer was speculative. I'm hoping someone here can help my ignorance. In electronics design, there are four ...
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1answer
68 views

Influence of a Capacitance Matrix of a voltage measurment

I am having a problem in understanding how in a multiconductor system the Capacitance Matrix influences the measure of voltage between two electrodes. In the case that interest me we have 4 ...
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3answers
860 views

electron flow in capacitor with dielectric

if I make a circuit with a battery and a capacitor (with a dielectric inside), how it is possible to get a current in the circuit? If electrons go from one pole of the battery and they arrive to one ...
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1answer
53 views

Capacitance of a free conductor

Consider a ideal conductor in free space.For all purposes here,the zero of the potential is taken at infinity. Suppose I give a charge $Q$ to the conductor.As a result,the conductor will have a ...
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2answers
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Does displacement current exist after the capacitor gets fully charged?

The displacement current is due to changing electric field. Since, after the capacitor gets fully charged there is no changing electric field there is no displacement current.(capacitor connected to a ...
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Capacitance and energy

So I've been reading about capacitance (Specifically in capacitors) and I'm wondering if this reasoning is sound, and why/why not: C = Q/U U = Q/C We also know that: U = E/Q So: E/Q = Q/C Q^2 = ...
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1answer
108 views

Capacitors in parallel and dieletric [closed]

I'm trying to solve this problem: Two capacitors of capacitance $C_1=200pF$ and $C_2=1000pF$ are connected in parallel and loaded to a potential difference of $400V$. Subsequently the space ...
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1answer
4k views

Delta to Star/Y Conversions and vice versa in Electric Ciruits

We all know the basic rules for conversion of $"Delta"$ circuits to $"Star"$ circuits and vice versa. We also know that this is needed for simplification of circuits in complex cases. Can anyone ...
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Is this configuration correct for this spherical capacitor? [duplicate]

This capacitance contain 4 dielectric as shown in the figure dielectric 1 in half sphere and 2,3 in for 1/4 of the sphere and the fourth one in the last 1/4 of the sphere as shown and I want to find ...
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3answers
86 views

Capacitor related query

Why does a capacitor charge only upto the voltage of the source? I mean in an r.c. circuit if we have a resistor that is in series with the capacitor then because of the potential drop there will be ...
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1answer
159 views

Realistic vs Idealistic capacitance

I am doing an investigation into the differences of calculating capacitance using the well know formula for an idealistic parallel plate capacitor, based on the assumption of a uniformly distributed ...
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1answer
160 views

Capacitors in parallel and capacitors in series

How can I recognize clearly when I deal with capacitors in parallel or capacitors in series? Can follow a "rule" or a intuitive method? I have to do difficult exercises regarding system of capacitors ...
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2answers
75 views

Coefficients of capitance

In my syllabus about electromagnetism, they introduce the coefficients of capacitance by stating that, if we have $n$ conductors enclosed by linear dielectrics, then we can write 'because of linearity'...
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1answer
468 views

What is the difference between a battery and a “polarized” charged capacitor?

I know that the main difference between the two is that a battery can provide a constant voltage whereas a capacitor's voltage decreases as the charge stored decreases. But what about the internal ...
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1answer
210 views

Field of a parallel plate capacitor

Pretty much in all the diagrams I have seen the electric field of the parallel plates is depicted as in this image The field lines seems to start bending only after leaving the periphery of the ...