Capacitor Definition and 1000 Threads

These are 2 stand alone problems, however the answers disagree with one another and I am trying to reconcile their differences. Any insight would be appreciated! :) The answer is C. The answer provided with this question is that "there is no dependence on resistance of any kind". However the...

Homework Statement A dc current of 3 A flows through an initially discharged capacitor. After 2 micro s what is the electrical charge on the capacitor? Homework Equations q(t)= integral i(t) dt between t=0 and t The Attempt at a Solution (3t^2)/2=6x10^-12 C. Is this right?

Hi, I would like to know how to insert a bypass capacitor in parallel with the power supply. I drew some GREEN lines as jumpers and BLUE line as bypass capacitor for you guys to check if that's the correct way to do it. NOTE: Ignore the jumpers, just look at the lines I drew with MS paint.

Homework Statement Given a capacitor, top plate with charge 2Q, bottom plate -Q: Find surface charge densities of all four surfaces and E-fields everywhere. Homework Equations The Attempt at a Solution I start off with the general case of top plate having charge Q1, bottom plate Q2. Inner...

I'm trying to cross check mathematically the mA being discharged from a .33uF capacitor which is charged to about 1200V by a circuit (see single_circuit.jpg) which is provided 37W of power to it. I do it three ways. 1) The circuit draws 35W total. 13V @ 5A = 65W. But the power supply drops...

Hello. Firstly, I'm new to these forums, so if this topic belongs elsewhere, I apologize. I've been struggling with certain concepts pertaining to electrostatics, and would like some feedback regarding as to whether or not I have the right idea in understanding how charge passes through a...

Homework Statement Thin parallel plate capacitor is connected to a U=600 V current source. Find the electric current flowing in the circuit if one of the electrodes is pulled at v=6 m/s velocity. The electrodes are square (l=10 cm), the distance between them is d=1 mm.Homework Equations...

BOB S had posted this in a now closed thread: https://www.physicsforums.com/showthread.php?t=360072 Regarding this analysis ... https://www.physicsforums.com/attachment.php?attachmentid=20126&d=1250393723 My questions ... Q1) Does this oscillation from the L-C circuit actually...

Question taken from Griffiths Pg 185, Problem 4.19: For part (b): -Why are the electric fields the same whether in dielectric or in air? In part (a), they are clearly different! -Why is σ_{tot} = ε_{0}E = ε_{0}\frac{V}{d} -In calculation of capacitance, why is the total charge (\frac...

Can a capacitor be discharged/recharged by using only one plate? I have a theoretical circuit with a transformer winding and a capacitor in series , one end of the winding is at +12v, then the other is connected to the capacitor , and the capacitor other plate connected to ground , what would...

Homework Statement A parallel plate capacitor consists of two plates, each of area A, separated by a small distance d. in this gap, a dielectric of relative permittivity εr and thickness d/2 is fitted tight against one of the plates, leaving an air gap of thickness d/2 between it and the other...

Homework Statement Estimate the required radius of each plate. The plates are separated in air by 0.01mm and has a capacitance of 400pF. There are 4 pairs of plates. Homework Equations c= εrε0*A(n-1)/ d The Attempt at a Solution Find area. Transposing for A A = dc/εrεo A=...

Homework Statement A practical capacitor can be modeled by an ideal capacitor in parallel with a resistor.Find the impedance of practical capacitor at the radian frequency ω=377rad/s.Known C1=0.1 x 10^-6F R1=1 *10^6. Homework Equations 1/Z=1/R1 + jCω The Attempt at a SolutionI am first...

A practical capacitor can be modeled by an ideal capacitor in parallel with a resistor.Find the impedance of practical capacitor at the radian frequency ω=377rad/s.Known C1=0.1 x 10^-6F R1=1 *10^6. I am first determining the Z, by adding the impedance of resistor and the capacitor in...

Homework Statement A parallel-plate capacitor of capacitance C with circular plates is charged by a constant current I. The radius a of the plates is much larger than the distance d between them, so fringing effects are negligible. Calculate B(r), the magnitude of the magnetic field inside the...

I don't well understand capacitance and its use in touch screens. Just had a crazy idea that you could involve a charged capacitor to enhance the accuracy of a stylus.

The current in a capacitor is calculated from i_{C}(t)=C \dfrac{dv_{C}(t)}{dt} when i_{C}(t) is the current in the capacitor, t is the time variable, C is the capacitance and v_{C}(t) is the capacitor's voltage. This equation can also be expressed, using \omega t as the variable, as...

Homework Statement Two related questions (from Electromagnetics by Notaros) The dielectric of a parallel-plate capacitor has two homogeneous parts, referred to as dielectric 1 and dielectric 2. The boundary surface between the parts is flat and parallel to the capacitor plates. The dielectric...

Homework Statement consider a capacitor with circular plates of radius a, separated by a distance d (d<<a) and V(t)=V_{0}sin(wt) a)Considering the z axis to be the capacitor axis, verify that the electric field between the plates is , in good approximation, given by \vec{E}(t)\approx E_{0}...

Hi all "A parallel plate capacitor in which plates of area A are separated by a distance d, has a capacitance C = \frac{Aε_{0}ε_{r}}{d} It is charged to a pd V. Neglecting edge effects, derive an equation for the electric field E in the capacitor, and show that the energy stored per unit volume...

Consider a capacitor with 4 parallel plates and 3 dielectric insulators arranged like this...+I-I+I- The insulator in the center has an equal amount of + and - charge on each side of it so shouldn't the electric field across this insulator be almost zero? If I constructed this capacitor with...

Homework Statement I can't seem to understand this problem (I do see that the inner cylinder and outer shell will have the same charge, but I can't see what I'm supposed to assume about the middle shell): A cable consists of three conductors, a solid inner cylinder and two thin...

Homework Statement A parallel-plate capacitor C , with plate separation d , is given an initial charge ±Q_{0}. It is then connected to a resistor R, and discharges, Q(t)=Q_{0} e^{-t/RC} 2 (a) What fraction of its energy Q_{0}^{2}/2C does it radiate away? Homework Equations The equations for...

Homework Statement A 3nF Capacitor is parallel with a 4nF Capacitor. And they are connected with a 5nF Capacitor in series. IF the external voltage supply is 20V. FIND (a)the p.d across each capacitor, and (b)the total charge in the three Capacitor. The Attempt at a Solution (a)...

Homework Statement Plates of a capacitor have charge 2CE and CE initially. Now the switch S is closed. Which of following statements is true? Assume that the battery, resistor and wires do not have any capacitance. A)There is no change in charge at outer surfaces of the capacitor. B)There...

Hi, I have the following theoretic setup: A cap of size C Farad is connected between nodes A and B and loaded with a specific charge (e.g. +10 on side A, -10 on side B). In the next step, i disconnect side B and before doing that, "magically" (see footnote) a charge of -3 gets injected on...

Homework Statement C1= 2.0 μF C2= 5.0 μF the resistor has a resistance of 0.10 MΩ The circuit shows the charging of a capacitor a) At t=0 the switch is closed. What is the initial measuring on the ammeter? b) After the current has decayed to zero what are the voltages at points A,B and C...

Homework Statement A 10-cm-diameter parallel-plate capacitor has a 1.0 mm spacing. The electric field between the plates is increasing at the rate 1.4×106V/m*s. What is the magnetic field strength 2.7cm from the axis? Homework Equations \ointB*ds=\mu\epsilondE(t)/dt*A...

Homework Statement A battery is connected to a capacitor made from two conductors. Why do each of the two conductors acquire the same charge,regardless of size or shape? Homework Equations The Attempt at a Solution Well, I can see that this is sensible, intuitively that the...

Homework Statement Hey guys, I am having problems with finding the maximum charge of a capacitor. From the experiment we are given R=100 Ohms, and Capacitance = 330 uF We are asked to find the maximum charge the capacitor has. Time to half charge was 0.0235 sec. Voltage is 4V Homework...

Homework Statement A 2.1 aF capacitor has a net charge of 0.5e (a positive charge, the symbol e is taken as a positive number 1.6 x 10-19 coulomb). What is the energy needed to add one electron (charge -e) to this capacitor? Homework Equations Energy in a Capacitor: U = Q^2 \div 2C...

Hello, I have this audio amplifier from Vivax AM 100. But it has somewhat weird problem. When you turn it on it starts buzzing but, not like buzzing on speakers but rather circuit starts buzzing, rattling noise. There is also like wax residue on the board, which i don't think its...

Homework Statement What happens to the potential energy of a capacitor with length d when said length d is doubled? Use the formula for the potential energy of a capacitor [U = 1/(2C) * Q]. After that, refer to the work done by moving the capacitor the distance d. These two approaches should...

Hi All, I would like to know what is the suitable capacitor value to be used in a three level flying capacitor(three-phase) with the input of voltage = 500V and resistance(load)=1K ohm while the inductance(load)=0.1H and also the switching frequency is 10KHz? Can someone brief me on how to...

Hi. The problem is: Show that this capacitor network can be reduced to one equivalent capacitor and find its capacitance Ceq. (The network is in the attached image) I've tried to solve this problem by eliminating the capacitors two by two but it never lead me to the correct answer: Ceq=2C. In...

The electrostatic energy in a capacitor is negative is it not? If one had enough positive and negative charge on the plates so that the electrostatic energy was greater in magnitude than the rest mass energy then the system as a whole would have a negative total energy. Would this be possible...

Homework Statement Show that the transformation w = e^{z} + z maps the infinite lines y = \pm\pi into semi-infinite lines u \leq u_{0}, v = \pm\pi. This is equivalent to transforming an infinite or edgeless parallel-plate capacitor (z-plane) into a parallel plate capacitor (w-plane). Sketch...

I've examined in lab how a capacitor acts within a circuit. In a case where we charge a capacitor in series with a bulb and then another capacitor, I get the circuit in charging.png. So let's say electrons in the circuit flow from the positive end to the negative end and the circuit flows like...

A parallel-plate air capacitor of area A= 21.0 cm2 and plate separation d= 3.20 mm is charged by a battery to a voltage 50.0 V. If a dielectric material with κ = 4.80 is inserted so that it fills the volume between the plates (with the capacitor still connected to the battery), how much...

A solar panel have a certain voltage at which it produces the most power. Below this voltage it's a current source - giving about the same current all the way down to short circuit. Right? On the other hand, a capacitor sucks up as much current as is available (ignoring ESR), slowly...

A capacitor consists of two closely spaced metal conductors of large area, separated by a thin insulating foil. It has an electrical capacity of 3000.0 μF and is charged to a potential difference of 87.0 V. Calculate the amount of energy stored in the capacitor. Calculate the charge on this...

Homework Statement Three capacitors, with capacitances C1 = 4.0 μF, C2 = 3.0 μF, and C3 = 2.0 μF, are connected to a 12 -V voltage source, as shown in the figure. What is the charge on capacitor C2 ?Homework Equations Q=VC Q = charge V = voltage C = capacitance Ceq = equivalent...

Homework Statement A parallel plate capacitor with plates of area 460 cm^2 is charged to a potential difference V then disconnected from the source of voltage. When the plates move .3 cm farther apart, the voltage between them increases by 120 V. What is the charge Q on the positive plate of...

Homework Statement Consider a simple defibrillator consisting of a capacitor which discharges across the two associated with the patient's chest electrodes in a period of 150 ms to about 5% of the fully charged voltage of the capacitor. The resistance of the chest between the electrodes...

I am confused about how to find the electric field between a discharging capacitor. For example, let's say I have a fully charged capacitor, such that there is no current flow anywhere. Then there is an electric field between the capacitor which equals 2*sigma/epsilon_0. But now the...

Homework Statement A 68 nF capacitor has a parasitic parallel resistance Rp = 1 MΩ. If a voltage V = Vmsin(ωt) is applied, as shown in the diagram, find the frequencies at which: 1. The current amplitude through the parasitic resistance is 1% of the current amplitude through the...

Homework Statement Three capacitors are connected in series across a DC power source that produces a constant potential difference. A fourth capacitor is now added in series with the other three. As a result of adding this capacitor, the total energy stored in the system of capacitors...

Homework Statement How much charge can be placed on a capacitor with air between the plates before it breaks down if the area of the plates is 5 cm^2. Homework Equations C=\frac{Q}{\Delta V} C=kC_o C=k\frac{\varepsilon _o A}{d} Where "k" is the dialectric constant. The Attempt at a...

After studying more complicated electronics, I find myself asking this question - 'Why capacitor works?' Why does charge get accumulated on the plates? Isn't that a higher energy state than battery?

Homework Statement Calculate the current in the capacitor shown if the voltage input is a. v1(t) = 10cos(377t - 30°)V b. v2(t) = 12sin(377t + 60°)V Give answers in both time and frequency domain. Homework Equations I = dQ/dt = C * dV/dt The...