Capacitance Definition and 903 Threads

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...

Given that two spherical conductors of radii r1 and r2 are separated by x>>(both r), connected by a thin wire, and charged with 7 uC - how is the charge distributed between the spheres (no charge on wire)? I tried using charge density but: Qtot/A1+A2 = Q1/A1 + Q/A2 doesn't work by...

The variable capacitor in the tuner of an AM radio has capacitance of 1800pF when the radio is tuned to a station at 550 kHz. a) What must be the capacitance for a station at 1600 kHz? I found the frequency first and then am I supposed to setup the 1600 equal to the frequency to find the...

OK, let's say you have identical capacitors, and you charge one and do not charge the other. Then you connect the two. Will the energy in the two-capacitor system be the same as the energy in the first capacitor before it was connected?

http://img.photobucket.com/albums/v64/neik7/asg.jpg this is neither a parallel nor a series circuit i duno how to find the equivalent capacitance from a to b can anyone give me some hint ? :cry: thanks in advance

Small question: The capacitance of parrallel plates decreases as you increase the distance between them, why? I know the voltage increases, because the electric field is constant, but how does this stop more charge from entering the plate? I mean our voltage relative to some far-off charge is...

A capacitor is often used in electronics to keep energy flowing even if there is a momentary loss of power from the electric company. What capacitance would be required to a 150-watt televisiion (plugged into a standard 120 volt ac outlet) to protect it from a .1 second lapse in power? I...

the general definition of capacitance is that if you have an arrangement of two conductors, and you put a charge +Q on one and -Q on the other, and a potential difference of V results between them, the capacitance is Q/V. But what if the charges on each conductor don't have the same magnitude...

Hi Guys, Here is a question that I cannot get my mind on. Bad day I guess. I'm trying to figure out the answer. Here comes the question: How far away from each other would two metal plates, 2 square meters in area each, have to be in order to create a capacitance of 1 micro Farad...

I've done a search for some help on my problem, but I haven't seen anything resemble it. Anyway my question is the following: Not all dielectrics that separate the plates of a capacitor are rigid. For example, the membrane of a nerve axon is a bilipid layer that has a finite compressibility...

How can I show that the capacitance of a plate capacitor increases if a dielectric material fills the space between the plates?

Here is the question A(n) 2.00 µF capacitor is charged to 520 V and a 4.60 µF capacitor is charged to 570 V What is the voltage for each capacitor if plates of opposite signs are connected? Any help would be helpful. I have bene trying to get this and haven't been able to all night. I...

A parallel plate capacitor has charge Q and plates of area A. What force acts on one plate to attract it toward the other plate? It's F = Q^2 / (2*8.854e-12*A) ... something to do with the electric field divided in 2? Wondering why there's a 2 in the denominator... thanks :)

Hi, I have a problem about the capacitance of two cylinders eccentrically located one inside the other - with radii a and b resp., their centers have a distance c apart. I've tried that with the method of images, considering the eqipotential "cylinders" of a system of two infinite parallel...

The electric field between the plates of a paper-separated (K=3.75) capacitor is 9.41E4 V/m. The plates are 1.75mm apart and the charge on each plate is 0.775E-6C. Determine the capacitance of the capacitor and the area of each plate? I got the voltage by V=Ed. and that came out to 164.675...

I just need a hint on this. 2 plates of a capacitor hold +1500 C and -1500 C of charge, respectively, when the potential difference is 300 V. What is the capacitance? I know I have to use c=Q/V, but which charge do I use the positive or negative?

if we introduce a conductor b/w the plates of a capacitor then what will happen? will the capcitance increase or decrease?

Hi, I have learned that as a capacitor discharges it emits some kind of a wave. Plz tell me wether the frequency of this wave increases as the capcitance of this capacitor increases. Or please tell me is there a way to find out the cpacitance of a capacitor by looking at the wave that this...

Hi, I have read that as a capacitor discharges, it emits electromegnetic waves. Plz tell me does the frequency of these waves increase as the capacitance of the capacitor increases. Thanks a lot, Chamal.

2 problems. I was just wondering if someone can help me start off the problem. The rest, I'll try to do because I don't know how to setup the problem. 55) A virus rests on the bottom plate of oppositely charged parallel plates in the vacuum chamber of an electron microscope. The electric...

A capacitor, in a series with a 720 ohm resistor, is being charged. At the end of 10 ms its charge is half the final value. The capacitance is about: a)9.6 uF b)14 uF c)20 uF d)7.2 uF e)10F Now how in the heck and I suppose to know this one. I know ohms law and I know how to find...

Hello, We haven't covered capacitance in class yet, but our lab involves the use of capacitors, so I thought I'd throw out a general question. We were asked to use the MOS FET Electrometer to measure charge, and we were given the formula: Q = CV Where C is the capacitance, and V is...