Capacitance Definition and 874 Threads

Homework Statement Determine the equivalent capacitance (in terms of C[SIZE="1"]0) between points x and y of each network of capacitors shown. Homework Equations For capacitors connected in parallel, C[SIZE="1"]eq=C[SIZE="1"]1+C[SIZE="1"]2+...C[SIZE="1"]n For capacitors connected in series...

A derivation of the capacitance for a parallel plate capacitor is as follows: [ assume uniform field, plate area is infinite in relation to the separation, the conductors are perfect conductors ] So, V=Ed where V=voltage difference between plates E= electric field (uniform)...

In my electromagnetics textbook ("Fundamentals of Engineering Electromagnetics" by DK Cheng) there is a typical problem with capacitance, conductors and cylindrical or spherical symmetry which pops up with different variations several times in the problems section of the electrostatics chapter...

I need to measure the capacitance of something as accurately and as quickly as possible. I also need the method to be very noise tolerant and not depend upon signal attenuation. I've been looking at several different methods so far on how to do this and so far I have found methods like the UTI...

A pump did not stop when operator pressed the emergnecy push button. He ran towards another start/stop station and pressed the stop button. Even then the pump did not stop. After a while according to operator the pump stopped on its own. Electrical expert says that this can happen because of...

Given two parallel plates, length a. One being on the x axis, starting at the origin. The other starting a distance, d up the y-axis at an angle theta (parallel to the x axis), for theta being small. I need to find an equation for an approximation of the capacitance. I know that if the...

Homework Statement I have two coaxial infinite cylinders and I must find their capacitance, where r_{1} < r_{2} Homework Equations The Attempt at a Solution I got an answer (for finite cylinders) that is inversely proportional to Ln (r_{1}/r_{2}). Assuming this answer is correct (if someone...

Homework Statement A wind power plant will not produce as much energy when the wind slows down. In order to provide power during these time periods it is proposed to store some power when it is operating in high winds in a capacitor. If it is desired to store the energy to power a town at 20...

Homework Statement The radius and the length of the central wire in a Geiger tube are 0.180 mm and 10.0 cm, respectively. The outer surface of the tube is a conducting cylindrical shell that has an inner radius of 1.50 cm. The shell is coaxial with the wire and has the same length (10.0 cm)...

Would the capacitance of the system be the same if we had one spherical shell around another (radii a and b) , versus a solid sphere of radius a surrounded by shell of radius b? I mean...if the charge we add to the solid sphere distributes itself completely on the surface, isn't the inner solid...

Hello, I have a question that's really bothering me. So I've been reading about projected capacitance touchscreens (the kind that's in so many cell phones, the iphone etc) and I don't understand what the physical property of my finger is that allows the screen to function. From what I've...

Homework Statement A 24-µF capacitor has an electric potential difference of 30 V across it. What is the charge on the capacitor? Homework Equations kq1q2/r2?, q/change in V? The Attempt at a Solution ive tried looking through my notes but i was absent don't understand this if you could...

Homework Statement What is the capacitance of the two metal spheres shown in the figure ? sphere one has 20nC of charge and the other has -20nC of charge. The change in voltage is 100V Homework Equations C=Q/(change in V) The Attempt at a Solution My question is how do yo...

I am missing something very simple... in my book, it gives, for capacitors in series, that: 1/C(eq) = 1/C(1) + 1/C(2) using numbers, it says... 1/C(eq) = 1/6.0 uF + 1/3.0 uF ... C(eq) = 2.0 uF I cannot figure out how they got C(eq) = 2.0 uF Thanks

Homework Statement A science-fair radio uses a homemade capacitor made of two 45 45 sheets of aluminum foil separated by a 0.30-mm-thick sheet of paper. Assume dielectric constant of paper is 3.0. What is its capacitance? Homework Equations C=k e0 A / d The Attempt at a...

Please help! Capacitance question! Does the capacitance increase, decrease, or stay the same if: 1. the charge on the plate doubles? 2. the potential difference across the plates triples? 3. the distance between the plates is halved? 4. area of the plates is doubled? 5. electric field is...

Homework Statement I apologize for having to upload an attachment but I couldn't describe this circuit. Basically, there is set of capacitors and the question is asking for the charge on one of them, when a 72 volt source is attached. All capacitances are 8.9 microFarads. Homework...

Homework Statement The coaxial cable from a television or other device has an inner conductor with diameter of 1 mm and the shield of diameter 5 mm. Assume a plausible value for the dielectric constant (3 ≤ κ ≤ 5) of the dielectric separating the two conductors and calculate the capacitance...

Homework Statement A coaxial cable used in a transmission line has an inner radius of 0.15 mm and an outer radius of 0.65 mm. Calculate the capacitance per meter for the cable. Assume that the space between the conductors is filled with polystyrene. (Also assume that the outer conductor is...

Homework Statement A capacitor, previously charged by a 1000 V source, is discharged through a photographic flash unit. The capacitor delivered an average power of 1000 W and the flash lasts 0.040 s. What is the estimated capacitance of the capacitor a. 40 x 10-6 F b. 20 x 10-6 F c. 60 x...

what is the relatiob between capacitance and frequency?.. Can anyone please me in simple words..couse i m confused about it, in some sites they says its proportional..and other says inverse...:(

Homework Statement A telephone wire of diameter 1mm is suspended 10m above the ground. Estimate its capacitance to Earth per unit length Homework Equations The Attempt at a Solution I've tried to solve the problem by using the formula for a cylindrical capacitor and got the answer...

Homework Statement My question is mainly just conceptual not an actual homework problem. So let's say there are two capacitors in a series. Their C equiv= (1/c1 + 1/c2) So to find the charge on either c1 or c2, you would do C equiv*V=Q. Why is it that Q is the charge for each of...

Homework Statement Find the capacitance of the parallel plate capacitor with 2 dielectrics below. Given that the parallel plate capacitor has area A = WL and the separation between plates is d. The Attempt at a Solution My method is to use integration. First solve for two small...

How does a forward biased p-n junction display capacitive effect? I understand that a reverse biased diode can exhibit capacitance with the depletion region acting as a dielectric, but in a forward biased junction, depletion region does not exist,so how does it show capacitive behaviour?

Homework Statement Find the capacitance per unit length of three long coaxial metal tubes, with radii a < b < c . A wire connects the innermost and outermost tubes (radii a and c). Homework Equations The Attempt at a Solution I'm a little confused as to how I should set this...

A working circuit contains a 3V power supply, a 5000uF Capacitor, and a 200ohm resistor. a) What is the time constant for the circuit? b) What is the charge in coloumbs on the capacitor at a potential difference of 3V? c) How much energy is stored on the Capacitor at a potential difference...

Homework Statement To find the equivalent capacitance of the following network (image attached at the end of the post). The blue capacitors have capacitance of 2C and the black ones have a capacitance of C. Homework Equations Q = CV where Q is the charge on a capacitor, C it's capacitance...

Hey friends, I am trying to make a digital capacitance meter by using a HSC08 microcontroller chip (MC9S08QG8). Unfortunately this is one of those courses where one doesn't know anything because of lack of pre-requisites. Anyhow (enough complaining) what I have been trying to do is the...

my book does not fare well in explanations, thus I have a few questions if the capacitor plates hold energy, how does this energy become released in certain applications? what are some common applications of capacitors? if the voltage difference in parallel capacitors are the same, why is...

Homework Statement Calculate the capacitance of a spherical capacitor such that its center and up to R_2 is vacuum. Then from R_2 up to R_3 there's a dielectric material of constant \kappa _2. Then from R_3 up to R_1 there's a material of constant \kappa _1. Homework Equations None...

Homework Statement An LC circuit consists of a 1mH inductor. The capacitor is fully charged. After 2.1 ms, the energy in the capacitor is ½ of its original value. What is the capacitance of the circuit? Homework Equations (Q/C)+ L(d^2Q/dt^2)=0 d^2Q/dt^2= -(1/LC)Q The Attempt at...

Homework Statement A 0.2uf and 0.1uf capacitor are connected in series to a 9V battery. Calculate a) the potential difference across each capacitor and b) the charge on each. Homework Equations Not sure The Attempt at a Solution I don't even know where to begin, sorry :(

Homework Statement Find the equivalent capacitance of the capacitor combination, Ct and the charge over C5:Q5 Vab=10V C1=3uF C2=11uF C3=12uF C4=6uF C5=9uF Homework Equations 1) 1/Ct=1/C1+1/C4 = 2uF 2) 1/Ct= 1/C2+1/C5 = 99/20uF Parallel: 2+99/20+12=379/20uF Ct=379/20 uF...

Homework Statement What is the equivalent capacitance of the arrangement shown in figure. (Answer is C1) Homework Equations Cparallel = C1+C2+...Cn Cseries = 1/(1/C1+1/C2+...+1/Cn) The Attempt at a Solution

Homework Statement sigh* Well, I have more than a week to do this lab, and usually I don't resort for help here, but on this lab there are so many things I am unsure of. So here's the setup of the lab: I have a one Farad capacitor, a DC power supply, a multimeter, a bunch of...

Does every object have a capacitance associated with it? For example, is there a capacitance in a single wire or a chair? If so, can you please explain why because I was taught that capacitance is associated with two conducting objects. Thank you.

Homework Statement V=8.8V (a) Find the equivalent capacitance between the terminals Answer= .242uF b.) Find the charge stored on the positively charged plate of each capacitor? C1=.3uF , C2=1uF , C3= .25uF So I have to find the charge on each plate of the three c.)Find the voltage across...

Homework Statement Have been given the task of creating a circuit powered by a rotating magnet in a copper coil that will charge a capacitor long enough to light an LED for 600 seconds after the rotating magnet has stopped. In all the magnet charge up torches I've opened, there are two 3V...

Homework Statement You are planning to install a home video studio. A very important piece of information is missing from the specifications. You must find the capacitance per unit length for a coaxial cable. The cable has an inner radius of 2.0mm and an outer conductor 4.0mm in radius...

Homework Statement The capacitance of each capacitor of the infinite series shown in the picture is C = 1\muF. Find the total capacitance between points a and b. IMAGE: http://img61.imageshack.us/img61/3674/pic002311.jpg" (continues to infinity) Homework Equations In series, (1/Ceq) =...

Homework Statement Your home video studio will use a TV antenna cable often known as "twin lead." Two 0.50mm--diameter wires are spaced 12mm apart. Your equipment requires that the total capacitance of the cable not exceed 1000 pF. The cable is 30m long. A technical paper on the cable gives...

What is the capacitance C of a capacitor that consists of two concentric spherical shells, the inner of radius r_{1} and the outer of radius r_{2}? What would the limit be if r_{2}-r_{1}<<r_{1}. What would happen if r_{2} goes to infinity (assume the potential there is zero)? Some equations...

Homework Statement Finding the equivalent capacitance of the supplied circuit. Homework Equations For parallel capacitors, C EQ.=C1+C2+C3+.. For serial capacitors, 1/C EQ.=1/C1+1/C2+... The Attempt at a Solution The circuit simplification is difficult!

1. Homework Statement [/b] You are planning to install a home video studio. A very important piece of information is missing from the specifications. You must find the capacitance per unit length for a coaxial cable. The cable has an inner radius of 1.1 {\rm mm} and an outer conductor 3.1 {\rm...

Homework Statement An air filled capacitor consists of two parallel plates, each with an area of 8.39cm^2, separated by a distance of .81mm. A 12.3V potential difference is applied to the plates. Find the capacitance. Answer in units of pF (pico Farad) Homework Equations 1. E = kV/d 2...

I have a question: I have two plates that form a right angle. How would I go about finding the Capacitance of the two plates?

Homework Statement A liquid-level transducer consists of two parallel plates of conductor immersed in an insulating liquid. When the tank is empty the capacitance of the plates is 200pF. The relative dielectric constant of the liquid is 25. Determine an expression for the capacitance C as a...

Homework Statement There is a parallel-plate capacitor with a plate area A = 5.52 cm2 and a plate separation d = 5.52 mm. The left half of the gap is filled with material of dielectric constant κ1 = 7.00; the right half is filled with material of dielectric constant κ2 = 15.0. What is the...

Homework Statement A capacitance matrix represents the charge coupling within a group of conductors — that is, the relationship between charges and voltages for the conductors. Given the three conductors shown in the following link, with the outside boundary taken as a reference...