Capacitance Definition and 903 Threads

Hello everyone, I have been tirelessly searching the net trying to find out how to calculate the distributed capacitance of a multi-layer bifilar coil. Just wondering if anyone here can point me in the right direction?

Hi everyone In most problems I've seen involving capacitance of a coaxial cable, there is an inner cylinder of radius a with +Q charge and and an outer cylinder of radius b with -Q charge. The voltage is calculated from a to b. However, in this problem the inner cylinder is -Q and the outer...

Homework Statement A flashlight uses 6.0J in 1.8ms (0.0018 seconds). First question: find the power. Got it: 3333W (3.3E3 with two sig figs, which is the accepted answer in the online system). The real problem: find the capacitance if the flashlight uses 200V. Homework Equations Power =...

Homework Statement A parallel plate capacitor of capacitance 5.2 µF has the space between the plates filled with a slab of glass with κ = 4.0. The capacitor is charged by attaching it to a 1.8-V battery. After the capacitor is disconnected from the battery, the dielectric slab is removed...

would a 1.5 volt electronic device that measures capacitance to turn on or off a regulator that controls water flow affect a defibrillator or pacemaker? Another way to ask this, A kitchen faucet that is touch sensitive would be safe or not safe for a heart patient who has defibrillator and...

Homework Statement Basically we did a lab on charges, capacitors and voltages. We used a 2200uF capacitor and we hooked it up with a 10kΩ Resistor connected in series with a DC Supply. The DC Supply was turned down to 0V and all the other senors were "zeroed" out. Simultaneously, when...

The energy of an RLC circuit decreases by 1.00% during each oscillation when R=2.00 ohms. If this resistance is removed, the resulting LC circuit oscillates at a frequency of 1.00 kHz. Find the values of inductance and capacitance.

1. The base of a cloud has an area of 2*10^7 metres squared and is on average 1km above the ground. treating the base of the cloud, the ground and the intervening air gap as a parallel plate capacitor, calculate the capacitance.[relative permittivity of air = 1.0] 2. I tried to say C...

Homework Statement The capacitance of the variable capacitor of a radio can be changed from 100 to 350 pF by turning the dial from 0° to 180°. With the dial set at 180°, the capacitor is connected to a 130 V battery. After charging, the capacitor is disconnected from the battery and the dial...

Homework Statement I have two coplanar electrodes (180 deg between them) and one of them is under voltage causing circular electric field between them. The target is to calculate the capacitance. Homework Equations Using the capacitance equation C = \frac{\epsilon_{0}A}{l} I say that...

What is the equation or conversion factor?

hello i need some explanation on this . I know that when a battery is connected it provides constant voltage across the capacitors. But the happens when the battery is disconnected. What happens to the voltage, the capicitance, and what is the importance of dielectric. I have read the book...

Homework Statement Capacitor C1 is charged so that potential difference between its plates is 20 V. Another capacitor C2=33µF has potential difference of 4 V between its plates. After plates of the capacitors that carry the charge of opposite sign were connected the potential difference became...

Homework Statement After the switches have been closed, in which circuit will the charge on the left hand capacitor increase? decrease? stay the same? Picture: [PLAIN]http://img714.imageshack.us/img714/3369/capacitance.png Homework Equations (1/Ceq) = (1/c1) + (1/c2) q = cv...

Homework Statement The equivalent capacitance of the capacitors shown in the figure is 9.23 MicroF Homework Equations http://upload.wikimedia.org/math/2/f/5/2f5b978fd081ea63e204909addf3d028.png http://upload.wikimedia.org/math/f/a/3/fa34ce461e6988fd973081401cc9790c.png The...

Homework Statement The equivalent capacitance of the capacitors shown in the figure is 9.26 uF http://session.masteringphysics.com/problemAsset/1122585/1/Walker.21.58.jpg Homework Equations Cseries = 1/Cs = 1/c1 + 1/c2 + ... Cparallel = Cp = C1 + C2 + ... The Attempt at a...

Homework Statement Hi again! I've been handed an assignment in which we are to find the capacitance of a variable capacitor consisting of seven semicircular plates with a radius of 2 cm spaced 1 mm from each other. Every other plate is connected to a common +terminal, and every other to a...

Homework Statement Hi, I have virtually no background in electronics and I have been given the following task. I have to measure the capacitance of the (real) circuit below (using labview, but it is the theory of how to do this that I am interested in). I am not able to use the...

Hi again! I got stuck in this question (Pic), the original question is the fig. 1. I then arranged the charges on the plates (fig 2) and then separated the plates to form three capacitors. Now I just don’t know what the capacitance will be and how to find it! First I thought to ignore the...

Hi all, This question was given in my physics book. Given that: C1 = 4uF and C2 = 6uF (u=micro) ... it comes out to be C1 + C2 = 10uF I used the general method ... you know ... assign charges, assume potentials... solve equations. My question is that aren't the two capacitors...

Homework Statement I have two wires (length L) which are separated by a distance d. They are also oriented perpendicularly (but I am curious about the orientation impact, part of the question). By simplification, I assume them to be cylinders of radius R (in actuality they are likely...

Hello, I need to construct an AM radio's RC circuit that: 1. resonates to frequency f= 580 Hz 2. has a maximum current of I = 0.2 A 3. the capacitor has a maximum potential energy U = 2 x 10^-5 I need to find: The inductance and capacitance (L & C) of this RC circuit. Please help...

Dear all, I'm having some trouble calculating the capacitance matrix, as outlined below. So first of all, the lecture notes I'm using use an integral equation method (method of moments) to determine the capacitance of two infinitely long and thin parallel strips in vacuum, at a distance d of...

Hello, I am new to this forum (and no physics expert). I apologize if this topic is in the wrong place, but I would really appreciate help on the abovementioned topic. I am investigating the effect of temperature on the capacitance of capacitors for a school project. Since C =...

Homework Statement Consider two long parallel and oppositely charged thick wires of radius d with their central axes separate by a distance D apart. Obtain an expression for the capacitance per unit length of this pair of wires Homework Equations \oint \vec{E}\cdot d\vec{a}...

Total Capacitance[SOLVED] Homework Statement how do i calculate the total capacitance of the image attached, as there is series and parallel capacitor in the same circuit The Attempt at a Solution i did try using 1/8uF + 8uF but then could not get the answer. can someone please...

Hey guys! This problem has been perplexing me for ages, and everything I do to try to solve it doesn't seem to work. So I was wondering if you guys could help point me in the right direction. Anyway: Homework Statement The figure below shows six concentric conducting spheres, a, b, c, d, e...

Homework Statement A battery with emf = 2V is connected to a RC circuit with a 450Ω resistor and an unknown capacitor. After 3.8 milliseconds, the current is 2.2mA. (a) Find the time constant and the capacitance. (b) Now, 2.9 ms after the charging begins, find the current I, the charge...

How does exactly higher capacitance have "more bang for your buck"? Hi! I'm trying to really grasp the concept of capacitance. Whenever I see a description of the definition, C=Q/V, they always say either: "More charge stored per potential", or "more bang for your buck". I don't really...

Capacitance (Please Help!) Homework Statement The charge on a capacitor increases by 21 \mu(micro) C when the voltage across it increases from 99 V to 127 V. What is the capacitance of the capacitor?Homework Equations There is Q=cV, or C=Q/v. But there are 2 unknowns and no number for the...

Homework Statement The oscillator of a 96.9 MHz FM station has an inductance of 1.4 μH. What is the value of the capacitance? Homework Equations I haven't the slightest idea. I've looked through the section in my physics book and looked all over online and I can't find anything. The Attempt...

I need a very accurate capacitance meter with capabilities down to + .01 puff. Any reccomendations?

Homework Statement Hi, i was working on finding the equivalent capacitance, but I'm not sure if I'm doing it right This is the figure : http://i8.photobucket.com/albums/a8/ryu0919/physicsproblem2.jpg? Homework Equations Find the equivalent capacitance? The Attempt at a Solution...

Homework Statement All the capacitors have the same value. Need to find the capacitance between ab. Homework Equations The Attempt at a Solution

Upon calculating the electric field for a plate of charge, you arrive at: E = Q/Ae (Q the charge on the plate, A the area of the plate, e the permittivity of the dielectic) But then, isn't the total electric field between the plates twice this because of the equal but opposite charge on the...

Homework Statement The plates of a parallel plate capacitor measure 15cm x 15cm, and they are separated by 6cm. The capacitor is charged with a potential difference of 18V, then removed from the voltage source and kept isolated. A 15cm x 15cm x 3cm slab of dielectric material (k = 2.5) is...

Homework Statement What is the equivalent capacitance of the four capacitors in the figure below? Take C1 = 2.6 µF, C2 = 4.1 µF, C3 = 3.9 µF, and C4 = 1.1 µF. Homework Equations Cequiv of capacitor in series = (1/C1)+(1/C2)+(1/C3)+(1/C4) Then take the reciprocal of the answer. The...

Homework Statement http://yfrog.com/mrcapdg http://img819.imageshack.us/img819/1172/capd.th.gif Find equivalent capacitance answer is 4C/3 Homework Equations whatever is in parenthesis is subscript formula1: series: 1/C(eq)= 1/C(1) + 1/C(2) + 1/C(3) + ... formula2: parallel...

Hi, can anyone tell me how to measure the parasitic capacitance in a generator?

Hi, How can I measure the capacitance of a capacitor, using the following: a battery, a digital voltmeter (which records voltage as a function of time), a digital ammeter (which records current as a function of time), an industrial capacitor, two copper plates, and several...

Homework Statement The problem considers the diagram in the photo that I have attached. Apologies for the poor quality, but sketching it on my computer would have been even worse! a) Write down Kirchhoff's laws for the circuit and show that when the switch is closed, the charge on the...

Hi guys, Today was the second time in a textbook that they calculated capacitance using C = \frac{dQ}{dV}. In my electromagnetics book and any sources I find online they use C = \frac{Q}{V}. Can anyone help me understand why they can do it like this? This type of calculation was done to...

Homework Statement [PLAIN]http://img806.imageshack.us/img806/2373/compquesti.jpg The Attempt at a Solution dont know where to start... i know i have to use complex numbers... advice needed please!

Can you tell me if I'm right with this. If you charge ten 1F capacitors in series at 10 volts. Each capacitor has a voltage of 1 volt and a charged capacitance of 0.1F. So if you discharged the ten capacitors in parallel the output would be equal to 1F of capacitance charge and 1 volt. or would...

Homework Statement Please, I would like to know how to find the factor by which the capacitance is multiplied A picture of the Op Amp is here: http://en.wikipedia.org/wiki/File:Cap-mult-op.svg Zc is complex impedance of C Homework Equations none given The Attempt at a Solution...

Does anyone know how to calculate the capacitance of a metal strip of width 2a and infinitesimal thickness? The length of the metal strip is much larger than its width. Thanks a lot!

Homework Statement At time t=0, a cell of EMF E and internal resistance r is connected to the capacitor of Capacitance C. i) Derive an expression for the voltage across the capacitor at subsequent times. ii) If the capacitance is 5000uF and the voltage across the capacitor reaches 73 V...

Homework Statement This is not a problem from any book or any kind of source. I was just thinking on this. Suppose u have a capacitor attached to a battery. And then u insert the dielectric slab. Then do the electric field between the plates changes? Homework Equations The Attempt...

Homework Statement The capacitance of a water-filled parallel-plate capacitor with plate area 3.0×10^−3m^2 and separation 4.0×10^−2 mm is 0.66 uF 1.3 nF 53 nF 660 nFHomework Equations C=E_0A/d The Attempt at a Solution C=8.85*10^-12*3*10^-3/4*10^-5 C=6.64*10^-10 This is none of the...

this type of cable is used to transfer power underground: http://www.mahanson.com/images/Hendrix%20Cable.jpg see the drain wires? i would think that those would be a huge problem because they are grounded and are right next to the conductor, i suppose any shielding would have this problem...