Capacitor Definition and 1000 Threads

1. The question: This question is from purcell's E&M book (3.71). (a) The plates of a capacitor have are A and separation s (assumed to be small). The plates are isolated, so the charges on them remain constant, the charge densities are +-σ. A neutral conducting slab with the same area A but...

Homework Statement A realistic capacitor is almost always filled with dielectric, but invariably this dielectric will conduct just a little, and the charge stored on the capacitor's plates will "leak." Over time, quite a bit of current can leak away. A good capacitor has a small leakage...

Homework Statement I'm having trouble understanding part C of this question. Homework Equations ΔVo = Vout/2fRC The Attempt at a Solution So to get ~12V at the output, the turns ratio should be 14 because 120√2/12 = 14.14. Using a turns ratio of 14, the output voltage will be 12.12 V. To...

Homework Statement I have a lab where I have to use two methods to find the capacitance of printer paper. Homework Equations C = kAeo / d The Attempt at a Solution From these slopes, I got k = .897 for the first type (using changing distance between the plates of the capacitor) for the...

How can a time constant, in parallel plates, be the original value without changing the capacitor?

Homework Statement I am attempting to understand this example shown below: Homework Equations During stead state DC, the capacitor is an open circuit and the inductor is short circuited. The Attempt at a Solution [/B] The questions I have are really related to the concepts as I don't...

If defibrillation is not required is there an alternative method to save the enrgy for the next needed defibrillation rather than to discharge the capacitor using a resistor ?

Homework Statement When a dielectric is partially inserted between two plates of a capacitor that is disconnected, what will be it's motion? Also what will be its motion if the capacitor is connected to a battery? Homework EquationsThe Attempt at a Solution For the first part. I think the...

Homework Statement A capacitor connected to a battery initially holds a charge of +q on its positive plate and -q on its negative plate. The electric field between the plates is initially E. A dielectric material is then inserted that polarizes in such a way as to produce an electric field of...

I found a motor I think is from an old AC unit in the recycle. It is a 1/4 HP, 265V, 1.20A AC motor. I've been looking to make a low-torque sander and was thinking about using this as a a drive motor. I know the starter capacitor is there to provide an initial burst of current to get it up to...

I have a DC source. then I connect a capacitor from the +ve to ground. if all connection are made from ordinary , copper for example, wires then electrons flow from negative to positive terminals.So electrons from the negative side of the capacitor would flow to the positive. I wonder what...

Hi , Can we replace battery with capacitor?? I know that energy stored in a battery is far greater than in the capacitors ,but still can we some how convert a charged capacitor into a temporary battery?? So the Question is how to control the discharge rate of capacitor? Is this have something...

Hi, I have been having this question for a long while. From Pozar's book (Microwave Engineering), on page 336, when he was solving for the resonance response and the Q factor for a Lamba/2 resonator terminated by an open circuit, and coupled to the feed line through a series capacitor, at some...

Homework Statement Homework Equations Force of attraction between the plates = (1/2)(QV)/d The Attempt at a Solution Initial charge on the capacitor Q1=CV Final charge on the capacitor Q2=2CV When switch is open force between the plates F1 = (1/2)(Q1V)/d1 = (1/2)(CV2)/d1 When switch...

Consider the arrangements shown in figure in which the north pole of a magnet is moved away from a thick conducting loop containing capacitor. Then excess positive charge will arrive on : (Plate B = answer) Am i correct in marking the side facing the magnet as south pole? ( because of Lenz...

I understand the situation when we charge a capacitor using a battery and a resistor placed in between serially placed ! V = iR + Q/C where we write i = dQ/dt whereas, V is voltage of battery R is resistance of resistor Q is charge on capacitor C is capacitance of capacitor i is current But what...

Homework Statement The switch is closed at the moment t=0 and initial capacitor voltages are V01 and V02. How to find capacitor voltage time dependencies for both capacitors. Homework EquationsThe Attempt at a Solution [/B]

Ok so my question(s) has more than one part. First, the energy stored in capacitor is ##(1/2)CV^{2}## , is the ##V## the voltage of the source that charged the capacitor?? If I had two identical capacitors, and charged one using a 9V source and one using a 12V source, would the one charged by a...

Homework Statement A 3.00 MΩ resistor and a 1.00 μF capacitor are connected in series with an ideal battery of emf E = 4.00 V. At 1.00 sec after the connection is made, what is the rate at which (a) the charge of the capacitor is increasing; (b) energy is being stored in the capacitor; (c)...

Capacitor connected to a battery of certain internal resistance. If it is asked to calculate what is power dissipated as heat, Does -the voltage across capacitor X current through capacitor- gives heat dissipated or should we add heat dissipated in battery by considering its internal resistance.

Suppose I first charge a capacitor so that one plate is positively charged and another negatively. Now I remove the charging source and ground only one of the terminals say negative terminal, will there be a net positive charge in the capacitor that can be detected by a pith ball? Can a...

Homework Statement The current in a series RLC circuit leads the generator voltage by φ = 30°. The circuit, containing an inductor L = 400 mH and a resistor R = 50 Ω, is driven by a generator operating at ω = 100 rad/s with a maximum emf of 10 V. The capacitance is unknown. The first question...

I KNOW WHAT CAPACITOR IS. IT'S AN EQUIPMENT THAT SAVES ELECTRICAL ENERGY. MY QUESTION IS THIS: LET'S IMAGINE WE HAVE A CIRCUIT : BATTERY, A LIGHT, AND CAPACITOR. CURRENT FLOWS THROUGH ALL OF THEM. CAPACITOR IS TRYING TO SAVE ENERGY,ITS VOLTAGE IS INCREASING, AND FINALLY, WHEN IT'S FULLY...

Homework Statement What is the voltage drop across the 1000 Ohm resistor when capacitor is fully charged? Homework Equations V(t) = {V_i}*e^{-t/RC} = {V_i}*e^{-t/Tau} The Attempt at a Solution In RC circuit experiment, initial is 9V and final is 2V. The voltage drop should be difference...

Hi, I'm trying to build a capacitor charger that can charge a capacitor to a higher voltage than the battery voltage I have. When reading up on charging capacitors, the simplest method seems to be wiring something similar to the capacitor charger for a camera flash. Unfortunately, a camera flash...

Homework Statement A dielectric-filled parallel-plate capacitor has plate area A = 15.0 cm2 , plate separation d = 9.00 mm and dielectric constant k = 4.00. The capacitor is connected to a battery that creates a constant voltage V = 15.0 V . Throughout the problem, use ϵ0 = 8.85×10^−12 C2/N⋅m2...

I want to calculate the total energy lost when a charged capacitor discharges to a neutral capacitor. It is my understanding that voltage will remain constant in the discharge, but current will decrease. What factors should be accounted for in any energy losses that would occur in this process?

We know that - VM=VCl - R1=1000.0 Ω - IM=0 - VNa=61 mV - VK=-88 mV - VCl=-71 mV Question is: what is R2?I've written according to Kirchhoff's second law that (1) VM + VNa - R1INa = 0 and (2) VM - VK - R2IK = 0. We can also calculate that ICl=0. With these equations and according to Kirchhoff's...

We have a circuit consisting of a charged capacitor and a resistor. First of all, we use Kirchhoff's loop rule to express this circuit in mathematical form. Now one teacher tells me Kirchhoff's loop rule yields iR+q/c=0. Another teacher tells me that the rule yields iR-q/c=0. Is there any...

I`m really a beginner when it comes to designing electrical circuits and only have the ability to replicate cicuit designs. I have no idea how to choose and power up a capacitor the way I want it. So what I need is a capacitor than I can charge up using a low voltage (around 5V) that can then...

Hi All, (First post, be nice). I'm analysing the discharge of a capacitor. Starting from the energy in a capacitor: E = \frac{1}{2} CV^2 This can be represented as follows (seen this elsewhere, there is nothing wrong with this): \Delta E = P \Delta t = \frac{1}{2} C(V^2_s-V^2_f) Where \Delta...

The question is the following: a) Determine all load voltages and currents b) Determine the resistance reflected into the primary. Answer a) R(l): 35V, 2.91A, X(cl): 15V, 1.5 A The answer to part (b) is apparently 34.5 Ohms. How did they arrive at these answers? I am not sure...

So, I've been doing a lot of spot welding and research/development of this manufacturing process I came up with a while ago, both of which involve high-energy capacitor discharges, and my previous 2.3kJ capacitor bank just wasn't cutting it anymore. So, I invested in 100 "Green-Cap" 2.7v 100F...

Homework Statement Plate capacitor with distance between plates 'd=4mm' is fully filled with homogeneous linear dielectric. Capacitor is connected to the source of DC voltage, first stationary state is established, then the capacitor is separated from DC voltage source. After that, dielectric...

I just started learning about capacitors in Electrical and Electronics Principles and I thought of a situation which I couldn't get a satisfactory answer/explanation from my lecturer. What happens if after charging a capacitor to 99%, I reverse the polarity of my power supply (or flip the...

Homework Statement A 10 ohms resistor, a 12 microFarad capacitor and a 28 mH inductor are connected in series with a 170 V generator. A.) At what frequency is the rms current maximum? B.) What is the maximum value of the rms current? Homework Equations A.) Fo = 1 / 2pi sqrtLC b.) Irms = Vrms...

Typically the power factor penalty that a utility charges is only for inductive lagging power factors or leading ones too? i.e. is the penalty for all PF differences from unity or only on the inductive side? e.g. Say I have a lot of motors which bring the PF down & I add a static capacitor...

Homework Statement Please see attached. Homework EquationsThe Attempt at a Solution I get a result of ## \alpha =\frac{1}{2} ## for part a) - which I think is correct. I'm stuck however on part b) - with the dielectrics. I have that the field in the region where the dielectric is ##E_{1}##...

Homework Statement The inner surface of one of the plates flat charged capacitor has a small hemispherical knoll. Away from it the electric field in the capacitor is equal to ## E_0 ##. Using the principle of superposition find the field at the top and at the base of the knoll. Homework...

Hi everyone. I have a problem with my device. It consists of a parallel plate capacitor with plates made of galvanized iron. Each plate's area is 1mx1inch. It's connected to a bleeder resistor and basically, the circuit is just a simple RC circuit. The source I'm using is a constant 5V DC...

I was wondering if there is any way to electrically charge photons?

example of a varible capacitor input op-amp to voltage level circuit. I'm not sure how to turn reactance to a voltage level using an op-amp? :wink:

Hey, we have learned in class that if you partialy insert a dielectric slab into a capacitor where voltage is held constant, there is a force pulling the dielectric farther into the capacitor. This gets me consfued. I know the more dielectric material there is in the capacitor, the capacitence...

can you charge a 12v car battery with capacitor

This question was taken from the public examination in my country/region. The answer from the marking scheme is, only statement 1 is correct and the others are wrong. Can anyone explain why the other statements are wrong? 1. Homework Statement The following components are connected in series...

I'm using a 3 phase 5HP motor pump n want to use capacitor. Which capacitor should I use and how to connect it to all the three phases? Please do needful

when we apply DC to capacitor then its capacitive reactance becomes zero and it acts like a short circuit...if it acts like short circuit then a huge amount of current will flow through the capacitor..isn't it? if so happens then what will happen to the dielectric present in between the two...

I need some clarification on batteries and capacitors. Before a battery is connected to a capacitor, the capacitor is uncharged. When a battery is connected, an electron from one conductor moves toward the positive terminal of the battery, leaving this conductor positively charged. What causes...

The related question says:[PLAIN]http:// The capacitor 1 is initially charged by having the flying lead attached to point C. Then, the flying lead is moved to point D. Capacitor 1 discharges. C2 has no charge intially. When the flying lead is attached to D, which one of these statements is...

Homework Statement (See image) 2. Homework Equations C=Q/V The Attempt at a Solution Part a took a while but I now understand that the electrons gather on the right plate of the 2μF capacitor and on the right plate of the 4μF capacitor. This imparts a negative charge of 133μC on each...