Capacitance Definition and 874 Threads

I would like to calculate theoretically the capacitance of a bearing with metallic rings and ceramic spheres (see http://en.wikipedia.org/wiki/Rolling-element_bearing. The expression for a cylindrical capacitor is: (2*pi*eps0*l)/(lnb/a). However, when adding some spherical balls inside the...

Homework Statement A known voltage source V_0 is connected by a switch to two capacitors in series with capacitance C_1 and C_2. When we flip the switch, connecting the capacitors to the voltage source, we measure the voltage across each capacitor, V_1 and V_2 respectively. I need to...

I have an assignment question with a variable capacitor in it and it asks what value of capacitance is necessary to provide "unity power factor overall". This wasnt explained in class, does anyone know what it means?

Homework Statement In the diagram V = 12.0V, C1 = 23 uF, C2 = 4.00 uF, C3 = 12.0 uF and C4 = 9.00uF. Calculate the equivalent capacitance of the system. http://img403.imageshack.us/img403/6346/eqam8.jpg Homework Equations Just combinding capacitors in parallel and in series...

I’m a bit confused on the relationships among C,V, and Q after reading my text. I don’t know if my reasonings contradict each other for the following. Homework Statement A capacitor of capacitance C holds a charge Q when the potential difference across the plates is V. If the charge Q on...

Homework Statement To repair a power supply for a stereo amplifier, an electronics technician needs a 100 micro-F capacitor capable of withstanding a potential difference of 90V between its plates. The only available supply is a box of five 100 micro-F capacitors, each having a maximum voltage...

Homework Statement http://img65.imageshack.us/img65/5993/clipboard01vk3.jpg Homework Equations Capacitance for series and parallel connected capacitors; C=Q/delta_V, derivations of last formulaThe Attempt at a Solution Part A C1 and C2 appear to be connected in series. Therefore, use...

1. 3 conducting spheres of radius a, b, c (a<b<c) are held at a potential of 0, V, 0 respectively. What is the capacitance of the system? 2. Q=CV (which I assume extends to Qi=CijVj for multiple conductors). 3. I've calculated the fields in the two interesting regions, calculated the charge on...

Homework Statement The two plates of a parallel-plate capacitor initially carry equal amount of positive charge. If some charges are transferred from one plate to another, the charges on the plates are respectively +900uC and +100uC. The potential difference across the plates becomes 4V. What...

[FONT="Courier New"]OOO|---C5----| OOO|OOOOOOOOO| A----C1---C2---C3----B OOOOOOOO|OOOOOOOOOO| OOOOOOOO|----C4----| The "C"s stand for capacitor. The capacitance of C2 is 10 μF and others are 4 μF. ---------- The book contains neither the answer nor solution. I tried to apply...

Hi, why is it that when u integrate V wrt to Q u get (CV^2)/2 instead of QV since voltage across is constant?

Dear friends, I am building a CDI system to ignite fuel mixtures in a pressure chamber for flame speed measurements. I need a capacitor of about 5 nF, but it should hold up to 10 kV. Any suggestions on where I can get those. I also need a diode (rectifier) for 10 kV. Also I need high...

Alright I have the answers... I was just hoping someone could explain how you would go about getting those answers http://us.f13.yahoofs.com/bc/44436150me3e0859f/bc/My+Documents/Picture+1.png?bfwadIFBB1QyCb1K" To Part A & B

I have learned how to find equivalent capacitence when capacitors are in series and when they are in parallel, but I came across a problem where I'm confused about the capacitors: Normally I first find equivalent capacitence of parallel capacitors by adding them together. Then use the...

Hi, Does anyone know an equation/approximation/model or other to estimate the capacitance between two coplanar (adjacent) plates? I know that for parallel plates: C = E0*Er*(A/d). I also know that the capacitance decrease as the plates move from a parallel to a coplanar geometry as the...

An axon is the relatively long tail-like part of a neuron, or nerve cell. The outer surface of the axon membrane (dielectric constant = 5, thickness = 1 10-8 m) is charged positively, and the inner portion is charged negatively. Thus, the membrane is a kind of capacitor. Assuming that an axon...

I've got a few more I need help with...I think I might have these ones, but not quite sure...as the concepts are still new to me. 1. If the voltage between the plates of a parallel plate capacitor is doubled, the capacitance of the capacitor... A. is halved B. remains the same C...

have a question in regards to capacitors in series. We are taught that the charge must be equal on all plates of the capacitors in the case of a series connection. However, we also know that Q = CV. If we increase V, then Q must increase. How is this possible for the node between the two...

does anyone know a site that offers a proof for the capacitance of a delta network? just curious 93157

another for the EE pros out there an isolated spherical capacitor has charge +Q on its inner conductor of radius r-sub-a and charge -Q on its outer conductor of radius r-sub-b. half of the volume between the two conductors is then filled with a liquid dielectric of constant K. a) find the...

Hello, I've learned from my study of oscillator circuits that an inductor has some inherent capacitance in it due to the distance between the individual windings. I've heard somewhere that if you place a permanent magnet close to a coil that it will behave like a capacitor and I was wondering...

I have thought about these questions, and although they seem easy I have different answers to them: 1) Consider a parallel plate capacitor with some capacitance C. The plates of the capacitor are connected to a battery that maintains a constant potential. If the plates are moved farther...

how would i rearrange this equation to find the capacitance, c? V=Vo exp(-t/RC)

Hi, I've attached a diagram of the question. The real question reads differently, but I've done my own interpretation. The interpretation might be wrong/ right, but its left me thinking anyway. So, I'd appreciate any advice/ hints on how I might go about finding the capacitance. I have tried it...

I know that Electrostatic Potential at a point due to a point charge is defined as the amount of work done in bringing a unit positive charge to that point (working against the electric force) But, I am unable to reconcile this definition with the phrases like "Potential of a conductor"...

Three equal conducting spheres A B and C of radius a are fixed at the vertices of an equilateral triangle of side B where b > 2a. When A is raised to potential V with B and C grounded, the charges on the spheres are q on A and q' on B and C. if all three were to be raised to some other...

The question is the following one: Two isolated conducting spheres of equal radius have charges +Q (#1)and -Q (#2) respectively. If they are separated by a large distance compared to their radius, what is the capacitance of this unusual capacitor? The first remark :wink: : C= \frac{Q}{V}...

A parallel-plate capacitor has rectangular plates of length L = 19 cm and width W = 3 cm . The region between the plates is filled with a dielectric slab of dielectric constant K= 4 which can slide along the length of the capacitor. Initially, the slab completely fills the rectangular region...

I have a problem where there is a capacitor (10 mF) charged to 15V, that is then placed in series with another capacitor (5 mF) and then an emf of 50V is added. I need to find the the potential across both capacitors. My question is can I combine the capacitors and make one since they share...

Question An automatic external defibrillator (AED) delivers 125J of energy at a voltage of 1050V. What is the capacitance of this device? Possible Ans Capacitance is charge / voltage. We have the voltage so how can you get a value for charge?

Hi:smile: , How are u? I want to know how is multimeter can value capacitor. also what is design for it, I mean farad unit in multimeter. Thanks I appreciate it :cool:

The way I understand extremely high frequency circuits to work is that in the design consideration it has to be considered capacitance across the traces. This becomes especially true as you increase the frequency. According to this website: http://www.adras.com/Impedance.t647-89-2.html...

this seems to be a simple question for the diagram at http://img.photobucket.com/albums/v11/biggm/ohm.jpg a)the circuit has been connected a long time...what is the voltage across the capacitor? this one i calculated and got the right answer of 6V. b)if the battery is disconnected how...

I Would like to come up with the capacitance between an infinite sheet and a finite area rectangle as a function of distance. I looked into my old E&M book, it did not consider edge effects I need to include those. Here is the situation. I just spent the day working with a capacitive sensor...

Hi I've been reading electromagnetism of late...in particular about parallel plate capacitors. So here are 2 questions about them. We generally consider the field between the two capacitor plates to be approximately equal to that generated by a pair of infinite conducting planes with equal and...

Hi all :) I need some help with the concept of parasitic capacitance. I'm currently doing some analysis on a basic tuned transistor circuit. I know the LCR portion of the circuit is there to remove parasitic capacitance. The only problem I'm having is I don't exactly know what parasitic...

see diagram for this at http://img.photobucket.com/albums/v11/biggm/cap.jpg Question: Determine the eqivalent capacitance C between terminals X and Y of the infinite set of capacitors represented. Each capacitor has capacitance Co. Suggestion: imagine that that ladder is but at the line...

In the figure attached, the battery has a potential difference of 10 V and the five capacitors each have a capacitance of 20 µF. What is the excess charge on capacitor 2? I go inside out from the capacitors in series C_2 and C_3. My notation simply denotes the equivalent resistance depending on...

The problem entails the following: Two conductors having net charges of +14.0 µC and -14.0 µC have a potential difference of 14.0 V. (a) Determine the capacitance of the system I know that the formula for capacitance is C=Q/V, but do I need to convert units, or add the two...

Hello everyone. The question is: What capacitance is required to store an energy of 8 kWh at a potential difference of 600 V? \This seems like a simple problem..our professor hasn't went over this yet but i saw in the book. P = U/t; I also saw; U = 1/2CV^2; So they gave me U right...

1. A RLC circuit is used in a radio to tune into an FM broadcasting station at 99.7 Mhz. The resistance in the circuit is 12.0 ohm, and the inductance is 1.40 uH (micro Henry) what capacitance should be used? this question is tricky what i tried to do is used XC=1/wC where C is capacitance...

I'm trying to calculate the capacitance across a couple of parallel plates but, for fun, one of the plates looks like a stair step. So it has 2 sections facing one normal parallel plate at different distances. I see two possibilities here, one being that I can simply treat the two sections as...

Hi, My question: A homemade capacitor is assembled by placing two 9-in pie pans 5cm apart and connecting them to the opposite terminals of 9-V batter. Estimate the capacitance? I know that to get the capacitance, you can use C=Q/V or C=keA/d. Do I need to find the area of the two pie pans...

2 Capacitors, C1 = 3*10^-12 f and C2= 6*10^-12 f are connected in series and the resulting combination is connected across 1000V a) the equivalent capacitance i got this 1/Ctotal = 1/C1 + 1/C2 b) total charge on the combination and the charge taken by each capicator ok here is where i...

The capacitance measurements of “Fuel Gauging Tubes” (FGT) that are composed of carbon composite inner and outer tubes shows unacceptable level of variations and I need to reduce the variation of capacitance. I would like to know what are the contributing factors to capacitance variations...

How can I get the parasitic capacitance of a inductor? I have a scope, current probe, function generator. Thank you.

Does it double or stay the same?

I am a struggling physiology PhD student and would very much appreciate some help... I need an expression for the capacitance of a cylinder (of finite radius and length) containing an infinite number of infinitely thin cylinders. Any help would be greatly appreciated! Many thanks, -Ian

I would like to understand why my 100uF 6.3V X5R dielectric ceramic capacitor decreases to ~60uF under a 5V applied DC bias. Can anyone explain the physical phenomenon?

Hi. I have this seemingly easy problem that I cannot get the right answer to! Here it is: A parallel-plate capacitor has circular plates of 6.00 cm radius and 2.00 mm separation. Calculate the capacitance. Ok, so I thought the formula for capacitance was [(epsilon)_0 x Area]/distance...