The ability of an object to store electric charge.

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2answers
51 views

Series circuit of capacitor and ohmic resistance: Voltage drop at Capacitor? [closed]

I have a question to an exercise I am currently trying to solve. It is given an Capacitor and an ohmic resistance in a series circuit. The whole voltage is 40V, the resistor has an resistance of ...
0
votes
3answers
59 views

Which makes for a better equivalent capacitor? In series or in parrallel?

I understand how capacitors in series and in parallel work. However, I am wondering if it makes a difference, in terms of making a better capacitor that can store more charge, would you connect them ...
0
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1answer
30 views

Imaginary component in capacitive reactance

This is a trivial question in first year but, unfortunately, this popped up in an elementary yet compulsory lab experiment. The capacitive reactance is defined as $$X_{c}=\frac{1}{\omega c}$$ The ...
0
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2answers
63 views

How does increasing the distance between 2 copper plates in a circuit affect the capacitance? [duplicate]

We have been told that the voltage decreases, but not been given a proper explanation by my teacher. Can anyone shed some light on this? Also, does increasing the distance between the plates of a ...
0
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0answers
31 views

Why should we use good conductors as electrodes of a capacitor?

I was asked if and why why should the electrodes of a capacitor should be good electrical conductors. It seemed obvious to me that if I want to form a Helmholtz double layer (because that's what ...
0
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2answers
38 views

Capacitor and Dielectric [closed]

Here's a homework problem: A $12 \mu F$ capacitor $C_{1}$ consists of plates $A$ and $B$. An $18 \mu F$ capacitor $C_{2}$ consists of plates $C$ and $D$. (a) Each are charged up by a $10 V$ battery ...
10
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5answers
4k views

Why does a ceiling fan start up slowly? [closed]

I think it probably has something to do with the capacitor inside but I don't get it why doesn't it just Start spinning instantly when we push the button why does it slowly start to spin and gradually ...
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3answers
37 views

Why does the current in a purely capacitive AC circuit lead the voltage by 90 deg?

1.When we mathematically derive the expression for the current from a sinusoidal voltage source (v=V sin(wt)), we take the derivative of q=cv where c is the capacitance. The final expression we get is ...
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0answers
21 views

Choosing between a parallel-plate and spherical capacitor model

This problem is solved in the solutions manual by making reference to equations for the parallel-plate capacitor. I have some basic understanding of why this is the case (the local curvature is small ...
0
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2answers
38 views

Spherical Conducting Shells, Potential

When we have a spherical conducting shell and charge on outer surface of the shell then the potential inside remains constant i.e, kQ/R (R=radius). But say the inner surface of the shell is charged ...
-1
votes
1answer
27 views

Things that must be considered when mass producing a capacitor [closed]

The question is to list four things that must be considered when a capacitor is chosen for inclusion in a circuit which is to be mass produced. Are there a specific set of four things? I've come up ...
0
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1answer
32 views

charge on the capacitors

When we connecting a capacitor to a battery of $V$ volts. After it is completely charged, it is disconnected from the battery, and if we connected to another capacitor. In this case, there is no ...
1
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0answers
41 views

Effect of potential difference on capacitance

I've read multiple threads here discussing the relation between capacitance and potential difference and they have begun to confuse me. I have a homework question about which of the following will ...
0
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0answers
41 views

When deriving potential between plates of parallel plate capacitor, why isn't the charge distributed on the top *and* bottom of both plates?

Let's say we have a canonical parallel plate capacitor with area $A$ and separation $d$ where $A>> d^2$. A charge of $+Q$ is placed on the top plate and $-Q$ is placed on the bottom plate. We ...
0
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2answers
33 views

Electric field Intensity , parallel plates

My book says that the electric field due to infinite long plates doesn't depend on 'r', so does it mean that no work is done in moving a point charge towards or away from it? Also considering the ...
0
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0answers
12 views

coaxial capacitor potential calculation

How is capacitance of a cylindrical capacitor calculated? In his question his Equation 1 tells us how to calculate the potential of a cylindrical object and there are two locations where I cannot ...
0
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2answers
38 views

What actually goes on in RLC circuit?

I already have difficulty understanding how each of the RLC circuit elements work individually as it is, and I have no idea how they work simultaneously in an RLC circuit. My schoolbook represents the ...
1
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0answers
28 views

Spherical capacitor with conducting wire [closed]

We have a spherical capacitor which consists of two conducting shells with radii $R_1,R_2$ with $R_2>R_1$. The two shells carry charges equal to $Q_1$ and $Q_2$ respectively (with $Q_2>0$) . We ...
0
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0answers
15 views

separation of the plates , charge stored, potential difference and energy stored

I have facing problem when comes to determine which formula should be used in some capacitor-based questions. For example, if initially a parallel plate capacitor with separation of plates d is ...
0
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2answers
50 views

Why don't capacitor charging graphs look like other exponential growth graphs?

Sorry if this question is stupid, but I can't find any answers for this online. Physics websites show that capacitors charge and discharge exponentially. The discharging graphs of charge against time ...
0
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2answers
53 views

Explaining why there is current in a circuit with a capacitor whilst the capacitor is charging

The question I'm trying to answer is part b) of the question below: My answer was: As some of the electrons will initially be repelled by the electric field of the negative plate, there will be ...
0
votes
3answers
63 views

Voltage drop across capacitors in series, why?

Basically when you connect more than 1 capacitor in series then the charge on each capacitor is same but there is a voltage drop across each capacitor. I have no intuition as to why the voltage drop ...
0
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1answer
35 views

Capacitors in an AC circuit

Can I combine capacitors in the same way for an AC circuit as I can for a DC circuit (In series or in parallel)? Does the same apply for simplifying resistors?
0
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2answers
71 views

RC circuit energy [closed]

I am quite new at circuit analysis and I have a question about a RC circuit, with the resistor and the capacitor connected in series. I want to find the energy supplied by the ideal voltage source ...
1
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1answer
32 views

How does a capacitor pass the flow?

Capacitor has just two conductor surfaces which have no touch. How can it pass the electric flow when there's no touch between the surfaces?
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1answer
32 views

Deriving the charge as a function of time in a discharging capacitor

There is obviously something I have not understood well. In Kirchoff's second law, we take the potential difference of batteries and capacitors with the sign that we traverse it. So, let's assume that ...
1
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2answers
82 views

Electric field between 2 parallel plates

The question state that 2 large parallel plates are a distance $d$ apart and the field at $d/2$ is $E$ if the distance between the plates are reduced to $\frac{d}{2}$ what is the field strength ...
1
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0answers
30 views

LCR circuit at resonance

I am studying about the LCR circuit and have a question regarding potential difference across inductor and capacitor. From the thing I have studied I came to know about that potential across inductor ...
1
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1answer
34 views

Equivalence between voltage drop across capacitors and resistors?

In simulating a circuit, comprised of 2 capacitors of same size but different dielectrics, their capacitance ratio ${C1}/{C2} = \epsilon2/\epsilon1$. Problem is, in finite element programs, I am ...
0
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0answers
25 views

Physics of the capacitance of an electrolytic capacitor

In explanations about the electrolytic capacitor one often cites the formula $$ C = \epsilon_r \epsilon_0 \frac{A}{d} $$ for the capacitance $C$. Then one says that by enlarging the area $A$ via ...
0
votes
2answers
76 views

Putting a capacitor into a strong magnetic field, will this change the capacity?

I'm wondering, does a magnetic field change the number of electrons, placed and displaced on the two plates of a capacitor. To prove or disprove this, I think the capacitor could be connected to an ...
0
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0answers
21 views

Triphasor Problem

Given the data presented in the following link I have to get $R$ for $P = 90~\textrm{kW}$ and the line currents $i_1$, $i_2$ and $i_3$. Any ideas?
1
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1answer
46 views

Equivalent DC circuit with charged conductors

I am trying to find equivalent circuit for a circuit composed of interconnected capacitors when isolated pieces of conductor may carry nonzero electric charge, and I have been struggling with this ...
0
votes
1answer
63 views

Self capacitance

I have two spheres of metal, each of radius $1m$, these spheres are effectively an infinite distance apart. I now connect a $1V$ power supply between these two spheres: (and wait an infinite amount ...
1
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0answers
30 views

How Calculate the electric field into capacitor [closed]

Hello i have a problem with this exercise with capacitor, I have to calculate the electric field between the capacitor plates (neglecting the edge effects ), but I do not know how to do Text: A plate ...
1
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1answer
35 views

Capacitance of Nested Spheres

Imagine that we have two nested spheres and I wish to calculate the capacitance. First of all, I'm able to do the calculation. What I'm confused about is how it is possible for the Electric Field to ...
0
votes
1answer
158 views

How the voltage of a capacitor is changed in charging/discharging [closed]

Capacitors are called fast batteries in electronics. I understand that a battery is charged by a constant current while the voltage is almost constant during charging and discharging. For example, a ...
0
votes
1answer
39 views

How does a capacitor get charged while the charger circuit isn't closed? [closed]

a capacitor is a very known device in circuits that can be used as a short-time battery by charging it using another source, but how does it really get charged? if the plates of the capacitor don't ...
0
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2answers
41 views

How is energy really lost due to heating in charging a capacitor?

Wanted to be sure, where is this understanding wrong? If a capacitor is charged to a potential difference $V$, then $Q$ in the capacitor would be $CV$. Now if we assume the voltage of the power ...
1
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0answers
93 views

Non-parallel plate capacitor's capacitance [closed]

So far, I fully understood how to find the capacitance of a parallel plate capacitor. However, for the case of non-parallel plate one, how one could solve that kind of problem knowing that one plate ...
0
votes
0answers
31 views

Differences between isolated parallel plate capacitors and parallel plate capacitors with a battery attached?

I think I get the general idea with what the difference is, which is that the battery creates a constant potential difference between the plates since the charge stays the same. I know that an ...
-1
votes
3answers
40 views

Why is it that when potential difference across a capacitor is equal to the supply voltage, no flow occurs?

Can someone explain to me how and why this happens? I'm really confused. I'm also confused about how the net charge between 2 plates is 0.
-1
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1answer
40 views

No change in voltage in a capacitor

While trying to solve this question: Photo copy of the question and answer: Question:On charging a parallel plate capacitor to potential V the spacing between the plates is halved and a dielectric ...
0
votes
2answers
93 views

A capacitor with a conductor between the plates [closed]

Consider a parallel plate capacitor of area $A$ with a distance between the plates $d$, disconnected from the battery. I wonder, how would the capacitance of the system change if we placed a conductor ...
0
votes
1answer
23 views

Charge in capacitor after switching voltage

Say you have a capacitor connected to a voltage source (vs). After the capacitor has fully charged, you cut the source voltage in half to vs/2. The voltage across the capacitor should change to match ...
0
votes
1answer
75 views

Circuit with three capacitors

A potential difference of V = 38.0 V is applied across a circuit with capacitances C1 = 4.1 nF, C2 = 4.7 nF, and C3= 2.3 nF, as shown in the figure. What is the magnitude and sign of q3l, the ...
0
votes
3answers
101 views

Definition of equivalent capacitance

I know that equivalent capacitance of multiple capacitors in series is $$ C = \left(\frac{1}{C_1} + \cdots + \frac{1}{C_n}\right)^{-1} $$ and in parallel is $$ C = C_1 + \cdots + C_n. $$ But there are ...
-1
votes
1answer
67 views

Capacitors and external electric fields

I am grading questions from the lab manual provided by the professor to review with the students. I am trying to wrap my head around one of the questions about what an external electric field would ...
0
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2answers
225 views

How is Capacitance affected by a seperation distance and with or without a battery?

The questions specifically says this : A parallel-plate capacitor initially has capacitance $C$. The distance between the plates is then doubled, with a $9.0V$ battery connected. The battery is then ...
0
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2answers
72 views

The separation between the two plates of a capacitor is increased

I had the following question on a quiz recently: A capacitor consisting of two parallel plates, separated by a distance $d$, is connected to a battery of EMF ε. What happens if the separation is ...