Capacitor Definition and 1000 Threads

Hi! I'm in a place where electricity goes out frequently; as a result I got a UPS which is powering my computer the total power input of which is less than 200W. The UPS is 300W or 600VA. The transfer time (time to switch from AC mode to battery mode) of the UPS is around 4 ms; but in that...

Homework Statement A 490 pF capacitor consists of two 19 cm -radius circular plates, insulated with polystyrene Find the thickness of the polystyrene. Homework Equations d = (ε_0 * Area * K) / C The Attempt at a Solution I converted 490 pF to F 4.90 * 10^-10 F I...

Homework Statement A parallel-plate capacitor has 4.0cm × 4.0cm electrodes with surface charge densities ±1.0×10^−6C/m2. A proton traveling parallel to the electrodes at 2.0×10^6m/s enters the center of the gap between them. Part A By what distance has the proton been deflected sideways when...

hello here in this problem as you see we want to obtain the pressure between thew plate of capacitor my question is about the capacitor each plate electric filed equation. as we know the electric filed of an infinite plate is but the equation of an conductor plate is...

Hi there! I have a problem that I would like explaining if possible (I like to go a bit beyond the GCSE course to get a deeper understanding of the topics!). Basically if I had a charged capacitor Cx with a voltage Vo across it which is connected in series with another capacitor Cy and a...

I have a slight issue with this derivation. Firstly, displacing one plate by dx requires work dW=-Fdx where F is the internal force between the plates resolved in the direction of x. I.e F=-dW/dx. If I do work on the capacitor W, this plus the energy provided by the battery to keep the...

I am having a difficult time understanding how they're transforming this capacitor schematic...what exactly is going on here? The example states that each cap is 7pF and the final answer C(eq) = 4.308pF...but why?

https://www.parts-express.com/dayton-audio-nd25fn-4-1-neo-silk-dome-tweeter-element-4-ohm--275-053 https://www.parts-express.com/cat/capacitors/68 Tried replacing the OEM speakers in my vehicle with a set of aftermarkets ...without exchanging the OEM head unit. Terrible idea, and I...

Homework Statement Specifically #13 only. Homework Equations Same image as above. The Attempt at a Solution Loop equations 10 - 500,000* i1 - 500,000 * i2 - 500,000 * i3 = 0 10 - 500,000* i1 - q/ 5 * 10^-6 - 500,000 * i3 = 0 Junction equations i1 = i2 + dq/dt i1 = i3 Solving for i1 in...

Homework Statement The Attempt at a Solution All I need to know is the acceleration acting on the particle after the potential is applied. v_f^2 = v_i^2 + 2ad (1*10^{-5})^2 = -(1*10^{-5})^2 + 2a(1*10^{-3}) a = 1*10^{-7} m/s2 Is this the correct approach to finding acceleration?

Homework Statement The switches have been in their initial positions for a long time, and switch to the other position at time t = 0s. Find v_0(t) for all t > 0. Homework Equations See the attached image for the circuit (I had to draw it because I don't have access to the original image...

Homework Statement We want to design a cylindrical vacuum capacitor of a given radius a for the outer cylindrical shell, which will be able to store the greatest amount of electrical energy, subject to the constraint that the electric field strength at the surface of the inner sphere may not...

The problem and solution are in the document. My question is in regards to the solution about calculating the charge on the capacitor. Would an equally correct solution for the charge be... Let σs be the surface charge density on the plate. The plate is a conductor and I would assume that the...

Homework Statement Hi, I have a quick question about applying the RC time constant formula for a lab report. In the lab, we charged a capacitor to 20 V and then let them discharge, recording the voltage every 10 seconds, up to 240 sec. Now I was asked to graph the time vs. voltage in excel...

Homework Statement To circumvent the negative feedback needed for thermal stability and to avoid the accompanying reduction of gain, a bypass capacitor CE needs to be placed in parallel with an emitter resistor RE, such as in Fig. 4.14a, cf. Fig. 18a. Determine what capacitor needs to be...

What happens if I connect a capacitor to a DC battery of 10 volts? At this point, there is a constant voltage across the capacitor of 10V, right? Now what happens if I remove the wire connecting the battery to the capacitor? Isn't that an abrupt change of voltage because it drops from 10V to 0V...

Homework Statement Problem statement in imageHomework Equations The Attempt at a Solution For this problem, I believe I am doing the math right, and getting infinite voltage at t=∞ However, in general there are so troubling facts to me in the problem statement. It is not so clear on the...

Homework Statement A spherical capacitor consists of a spherical conducting shell charge -Q concentric with a smaller conducting sphere of radius 4.0 cm and charge Q. The larger conducting shell has inner and outer radii of 11.0 cm and 13.0 cm, respectively. What is the capacitance of the...

Electrostatics -- 3rd plate inserted into parallel plate capacitor Homework Statement This question is from the book by I.S Grant and W.R Phillips on Electromagnetism. Two large parallel plates of area A and distance d apart are maintained at potentials 0 and V. A third similar plate...

Homework Statement A small bead of mass m= 34 g and charge of Q=140 mC has a velocity (all in the horizontal direction) of 7 m/s as it enters the gap of a parallel plate capacitor, initially traveling parallel to the plates. The plates are separated by 4 mm. If the bead enters the capacitor...

A 9.08 microFarad capacitor is measured to have a reactance of 245.0 Ohm. At what frequency (in Hz) is it being driven? I converted 9.08microFaraad in farads- 9.08x10^-6 THe formula i used was 1/(2*pi*f*9.08X10^-6) -- f = 17528.07 Hz but i am not sure if this is the right answer.

A coil in a magnetic field produces a sinusoidal emf output, so why can't you just attach a capacitor to it to charge it? Is it simply because capacitors store energy in electric fields, so you would need an inductor?

Charging/discharging of capacitor. Homework Statement Attached to this post, I have two circuits. The left, circuit 1. The right, circuit 2. For circuit 1 I'm supposed to compute T (tau). Find the expression for Uc1(t) and IR1(t). This is regarding discharging of a capacitor. For...

Homework Statement In a plate capacitor, the plates has a area of ##100cm^2## and a distance of 3mm. The insulation between the plates is a 1mm glass plate (εr = 10), a 0.5mm thick mica plate (εr = 5) and the rest is air. The insulation layers is parallel with the capacitor plates. The...

Hello, members of physics forums. This is my first post and question. As such, it will be quite basic. In an electric field, a conductor with a neutral total charge is placed. All the charges in the conductor will be on the surface, negative charges against the external electric field, positive...

Homework Statement The insulation in a plate capacitor consists of two layers with the thickness of 1 and 2 mm, and a relative permittivity of 4 and 6. Calculate the field strength in the thinnest layer when the capacitor is connected to a voltage of 5000v. Homework Equations The...

Hi guys, I'm a new member of this forum. As a chemist, I don't have much knowledge of electrical engineering, and that's the reason why I'm here. Hope you guys can help me out. I'm going to go straight to the point. I need to build a capacitor connected to an AC generator with an AC frequency...

[b]1.Question: A charged capacitor is connected across an 8.0 kΩ resistor and allowed to discharge. The capacitor loses 63.2% of it's original charge in a time of 6.2 seconds. Calculate the capacitance of the capacitor. (This is everything they give and nothing extra, I have checked and made...

Homework Statement The voltage across the capacitor is 10V when t<0 The switch is closed at t=0 I have to find the diff eq. in terms of Vs, C, R by balancing the current at node Vc(t). But i am not sure whether the Vs is 0 or 10V at t<0 The Attempt at a Solution I am assuming Vs...

Homework Statement A spherical capacitor with inner and outer radii a and b, contains a dielectric material with small conductivity \sigma between its spheres.Find the vector potential and magnetic field of this configuration. Homework Equations The Attempt at a Solution \nabla^2\phi=0...

My prof gave two formulas without much explanation as to where he got them from. For a parallel plate capacitor he gave it as E=k2∏q/A and for a cylinder he gave E=kq2/Lr where L is the length of the cylinder and r is the radius and A is the area. Can someone please explain how he derived these.

I am quite puzzled about charging a capacitor. Given a resistor, in series with a capacitor and a battery, when the switch is closed 1. Why there is a current immediately The capacitor is separated by insulator, hence this is not a closed circuit. The appearance of current seems to be a...

Homework Statement A thin spherical shell made of plastic carries a uniformly distributed negative charge -6e-10 coulombs (indicated as -Q1 in the diagram). Two large thin disks made of glass carry uniformly distributed positive and negative charges 1.5e-05 coulombs and -1.5e-05 coulombs...

A certain capacitor has a capacitance of 5.0 μF. After it is charged to 5.0 μC and isolated, the plates are brought closer together so its capacitance becomes 10μF. The work done by the agent is about: I assumed Qfinal = Qinitial since I believe there is still some separation, right (it's...

I hear of people discharging them with screwdrivers, but is that the best call for 10000+μF capacitors?

So far I have learned about Coulomb's law, the electric field, gauss's law, the electric potential and now capacitance. I feel that although I "know of" these topics, I don't actually "flow with them". Ignoring the math for a second; I want to form an understanding. And I think calculating the...

Hi there.. I was experimenting with capacitor discharge arcs. I charged a 340μF cap to 9v and shorted the terminals of the cap. Zap! Sparks!.. Then the terminals got stuck to each other as if they had been glued together! It took me 3-4 seconds pulling at them to separate them. It happens every...

There is a spherical capacitor with inner and outer radii of a and b respectively,has a dielectric material of small conductivity \sigma between its concentric conducting spheres.Calculate vector potential and magnetic field arising from this configuration. This is how I did it...

Homework Statement A conducting spherical shell is divided into upper and lower halves with a narrow insulating ring between them. The top half is at 10V and the bottom half is at -10V. Write down the appropriate expansion for Φ and use symmetry and the expected behavior at the origin to...

Hello , It's been a little while since I haven't written anything here.A recent thread was directly on topic with what I was wondering here about a little longer ago and the answers I got were good ofcourse but I'm still not convinced about the workings of my scenario , so I will redefine my...

There was a thread a while ago regarding a capacitor where the capacitance was changed while it was part of a circuit. I won't link the thread here as it was kind of a train wreck... Now the explanation given was that in order to change the capacitance work would have to be done to cause...

My book says it is zero, but I don't know where to start , why is it zero ? I have to take an exam in few hours :cry: so a simple explanation would be appreciated ( I'm not studying pure physics:smile: Here are the electric fields of the three regions . Thanks in advance :smile:

Capacitor energy problem?? Homework Statement A capacitor in this device is charged to 6417.0 V and stores 208.0 J of energy. What is its capacitance? Homework Equations i know the equation but dnt know how to use it . . C=(kEoA)/d The Attempt at a Solution I don't know how to...

Homework Statement A parallel-plate capacitor with C = 16 mu or micro FF is charged so as to contain 1.7 J of energy. If the capacitor has a vacuum between plates that are spaced by 0.35 mm, what is the energy density (the energy per unit volume)? I am a little lost of this problem and...

Homework Statement A voltage of 14 V is placed on a capacitor with C = 113 pF (picofarads). (a) What is the charge on the capacitor? (b) How much energy is stored in the capacitor? I believe I have the correct equation but I'm not sure about the final answer because of the picofarads...

I'm investigating the derivation of the equation $W=CV^{2}/2$ for the amount of work it takes to charge a capacitor of capacitance $C$ to the point that the voltage across it is $V$. In Griffiths' Introduction to Electrodynamics, 4th Ed., this is Equation 2.55 on page 107. In his derivation, he...

Homework Statement Two circular disks, each of area 4.10×10-4 m2, are situated parallel to one another. The distance between them is small compared with their radii. Both disks are uniformly charged; their charges per unit area are σ = 5.00×10-5 C/m2 for one and -σ = -5.00×10-5 C/m2 for the...

Homework Statement Two circular disks spaced 0.50 mm apart form a parallel-plate capacitor. Transferring 1.70 ×109 electrons from one disk to the other causes the electric field strength to be 3.50 ×105N/C. What are the diameters of the disks? Homework Equations Refer to attachment...

Can some check my answer, please? I only did number 1 because I have no idea how to do number 2. NOTE: Calculators are not allowed, so no need to give the exact value. For example, if the answer has √2, just leave it as √2, instead of writing it as 1.41... Power source voltage e(t) =...

Hi to all, It may be a low-level question, but nevertheless, one to which I'm looking for an answer. The main question is as follows: - Within a Tesla coil, what is the main purpose of the capacitor and spark gap? Other such questions arising from the principle question: - What would...