Capacitance Definition and 874 Threads

Calculating the Capacitance of "out of alignment" finite parallel plate capacitors Homework Statement Homework Equations The Attempt at a Solution

Homework Statement If I have an impedance of: 10+j4 ohms and was told to add a capacitance of -j15 in parallel to this, would this make the impedance 10-j11 ohms??

Hi Guys, I seem to have forgotten most of EM, but I was hoping for some help on estimating the capacitance of a wire mesh/grid parallel to a solid plane. I'm guessing that it will follow the form of a simple parallel plate (with the appropriate area factor) if the geometries are such that the...

1.If I double the diameter of a cell, by what factor does the capacitance of the membrane change? 2. Help! The Attempt at a Solution

Homework Statement A parallel plate air-spaced capacitor has a capacitance of 100pF. It is immersed in a fluid of resistivity 10 m. Calculate the resistance between the plates. Homework Equations C = \frac{\epsilon_0A}{d} R = \frac{\rho l}{A} The Attempt at a Solution I...

Homework Statement http://smg.photobucket.com/albums/v68/jumpboyb/?action=view&current=scan0001.jpg" Pretty much looking for a general equation for capacitance of a coaxial cable per meter length. given: -a diagram (click link) -two radii -dielectric material -outer conductor is...

can electron energy levels just be considered the self capacitance of an atom?

I am studying the relationship between transmission speed in a Transmission Cable and the temperature of the cable. This speed is given by (as per discussion in the Feynman lectures) v=\frac{1}{\sqrt{LC}} where L is the inductance per unit length C is the capacitance per unit length...

Homework Statement Hello, I was given this problem as a homework assigment. Each capacitor in the figure has capacitance C. What is the equivalent capacitance between points a and b? The answer is given in "C_eq/C" Homework Equations I used the...

Homework Statement I am trying to solve a question where I have three concentric metal shells at different radii. I am treating them as two capacitors in series. I would like to use the formula C= enot*area/distance between capacitors, but I have a few questions. Homework Equations...

Each pixel in a device acts like a parallel plate capaciter with the transistor updating at a voltage of 50 Hz. The change in voltage over 1 frame is 1 % and dominated by the electrical resistance of the material. The material has a constant dielectric of 20. Find the electrical resistivty of...

If I replace a 16 volt rated capacitor of 47uf with a 64 volt rated capacitor of 47uf, will the working capacitance be the same or does this depend on the specific design and materials of the capacitor? I'm thinking that the capacitance is proportional to the voltage applied and that the...

Homework Statement If an uncharged parallel-plate capacitor (capacitance C) is connected to a battery, one plate becomes negatively charged as electrons move to the plate face (area A). The depth d from which the electrons come in the plate in a particular capacitor is plotted against a range...

Homework Statement FM radio stations use radio waves with frequencies from 88.0 to 108 MHz to broadcast their signals. Assuming that the inductance in an LC-tuned circuit has a value of 7.60 x 10-7 H, determine the range of capacitance values that are needed so the antenna can pick up all...

Hey, I have a length of pipe. Inside the pipe walls I have placed four electrodes. If one is giving out x volts, and I know the dielectric constant of the material between them, is there an easy way of finding the capacitance on the other three electrodes? I'm looking for hints as well as...

Homework Statement C2<C2<C3<C4 for the capacitor combination shown. What is C_eq? a) less than C1 b) more than C4 c) between C2 & C3 d) less than C2 e) any value since it depends on the voltage applied Homework Equations Capacitors in series: 1/Ceq = 1/C1 + 1/C2 +... 1/Cn The...

Homework Statement A 13-µF capacitor and a capacitor of unknown capacitance are both charged to 4.00 kV. After charging, the two capacitors are disconnected from the voltage source. The capacitors are then connected to each other--positive plate to negative plate and negative plate to positive...

1What is the difference between heat capacity and heat capacitance?

Does anyone know what the value of capacitance in a vacuum (C_{0}) is? Would this be a constant or dependent on the particular capacitor? Thanks

Hi, Does anyone know if there is a relation between a materials capacitance (C) and its dielectric constant (K)? Thanks,

Homework Statement The capacitor in the figure below has a large capacitance and is initially uncharged. After the switch is closed, what happens to the lightbulb? You can't paste the figure but it is a circuit with a capacitor paralled to a battery and in series with a lightbulb. a...

Hi all, I'm a little stumped with how the dielectric increases capacitance. The general solutions all involve using the formulas, but don't really treat it conceptually. I realize that inserting a dielectric decreases field strength, and hence decreases the voltage across the capacitor. But...

I'm having some trouble calculating the values I need for a capacitor and inductor for a passive filter. The values that I know to use are current, voltage and frequency. But I have a voltage <1 volt and a frequency of 60Hz but no current. Can someone help me figure out what value of capacitor...

Homework Statement The magnetic field at one place on the earth’s surface is 55 μT in strength and tilted 60° down from horizontal. A 200-turn coil having a diameter of 4.0 cm and a resistance of 2.0 Ω is connected to a 1.0 μF capacitor rather than to a current meter. The coil is held in a...

As a crude model for lightning, consider the ground to be one plate of a parallel-plate capacitor and a cloud at an altitude of 620 m to be the other plate. Assume the surface area of the cloud to be the same as the area of a square that is 0.40 km on a side. (a) What is the capacitance of this...

I'm not too fond of writing the math down here, so I need only those who know their circuits to reply. Battery connection is maintained with one capacitor. du goes up as you insert a dielectric dc goes up dq goes up However, foe those who've done the thinking and solution...we find...

Homework Statement A series RLC circuit has a resonant frequency of 6.00 kHz and a resistance of 575 ohms. When connected to an AC power supply that varies the voltage at 8.00 kHz, its impedence is 1.00 kOhms. What are the capacitance and inductance of the circuit? Homework Equations...

Homework Statement What will increase the capacitance of a capacitor? Homework Equations Q=CV V = Ed The Attempt at a Solution Factors that increase: -Decrease in distance -Increase in charge -Decrease in electric field -Increase in area (length and width of the capacitor...

What is the purpose of a capacitance bridge? let's say 4 capacitors are arranged ...../.|.\ .....c1..|..c2 ...____ /...0...\ _____ ...|...\...|.../...| ...|...c3..|..c4...| ...|...\..|../...| ...|......| ...|......| 0 indicates the voltmeter. if 0 indicates a potential of 0, we get...

Find the capacitance per length of a co-axial cable with a conductor of radius a and a thin shield of radius b.

Hihi, http://sales.hamamatsu.com/assets/applications/SSD/si_pd_circuit_kspd1043e06.pdf 5. high-sensor From the message there, I don't understand what is the meaning of time constant of resistor? Why does it say that the time response of the circuit depends on the time constant...

1. Homework Statement a potential difference V = 100 V is applied across a capacitor arrangement with capacitances C1 = 11.0 µF, C2 = 7.00 µF, and C3 = 3.00 µF. Find the following values Charge on each capacitor, potential difference on each capacitor, and stored energy in Joules. The circuit...

I was wondering, If we had a system in which we limited the stray capacitance by shortening the cable (standard co-ax) to about 1 foot, and we put a REALLY fast signal down there, say of the order of fs. Would we see a sharp spike which was of the order of the RC time constant (capacitance...

Would you kindly help me in describing the relationship between 1. capacitance and voltage and why? and 2. Why does with increase in frequency the capacitance decreases ?

Homework Statement An air-filled spherical capacitor is constructed with inner and outer shell radii of 7.00 and 14.0 cm, respectively. (a) Calculate the capacitance of the device. (b) What potential difference between the spheres results in a charge of 4.00 microC on the capacitor...

Homework Statement Three capacitors of capacitance 8, 9, and 5 μF respectively, are connected in series to a 4 V battery. What is the charge on the positive plate of the 9 μF capacitor? Homework Equations Q = C*E 1/C = 1/C1 + .. The Attempt at a Solution I drew out the circuit...

Homework Statement In figure 25-29, a potential difference of V = 100 V is applied across a capacitor arrangement with capacitances C1 = 13.0 µF, C2 = 6.76 µF, and C3 = 4.14 µF. If capacitor 3 undergoes electrical breakdown so that it becomes equivalent to conducting wire, what is the...

Homework Statement two parallel plates have equal and opposite charges of 0.01 coulombs. the electric field between the plates is 10^5 Newtons/coulomb and the separation between the plates is 2mm. what is the capacitance of the plates? Homework Equations capacitance C = Q/V where Q is charge...

Homework Statement a 100 pico Farad capacitor C_1 is charged to a potential difference of 50 volts. the charging battery is disconnected and the capacitor is then connected to a second uncharged capacitor C_2. if the potential across C_1 drops to 35 volts, what was the capacitance of C_2...

Does anyone know how to calculate the capacitance of two circular plates having different dimensions? Say the top capacitor plate has a diameter d1 and the bottom capacitor plate has a larger diameter d2 and air is in between the bottom and top plate. So, it is not a standard parallel plate...

I want to calculate the capacitance of a system consisting a parallel plate and dielectric spheres of different radius and dielectric strength in between the plates. please give some mathematical derivation. I really need to know it,my career depends on it. Please help me. :) thanks &...

Homework Statement The sketch below is a side view of two capacitors consisting of parallel plates in air. The capacitor plates are equal in area but the plate separation differs as shown. Individual capacitors are specified with two letters, for example WX is a single capacitor. The charge on...

Consider a capacitor which is just like a plate capacitor, but instead of the upper electrode being a plate it is a point charge Q. the lower plate is held at a fixed potential V=0. how could you calculate the capacitance of the system? when trying to calculate - it looks like it will be 0...

[SOLVED] Capacitance and electric fields Homework Statement I want to find the capacitance of a parallel-plate capacitor consisting of two metal surfaces og area A held a distance d apart. First I find the electric field, which I know is \frac{\sigma }{{2\varepsilon }}. Then I use that the...

I'm trying to figure out the capacitance of the attached system. may I look at this problem as N capacitors attached in a cascade connenction? I'm also trying to figure out the force that will be felt by the point charge. I thought about using the image method... could you thing of a...

Hi, I am reading conflicting things about self Capacitance when Shielding a Coil, can someone help.. IE: I have a coil of wire --say 25 turns, 250mm dia formed from looping in my hands & bound together with a non conductive thread. I have read on some sites that there is no affect on...

Homework Statement 21. A certain transmission line is constructed from two thin metal “ribbons”, of width w, a very small distance w<<h apart. The current travels down one strip and back the other strip. In each case it spreads out uniformly over the surface of the ribbon. a) Find the...

Homework Statement The sketch below is a side view of two capacitors consisting of parallel plates in air. The capacitor plates are equal in area but the plate separation differs as shown. Individual capacitors are specified with two letters, for example YW is a single capacitor. The charge on...

Capacitance= (permitivity x Area of overlap)/ distance between two plates Why is capacitance inversely proportional to the distance between two plates? I understand that C=Q/V. So capacitance is the amount of charge it takes to change the potential difference between the two plates by 1...

Homework Statement A circuit consists of a Zener diode, capacitor and resistor in parallel. Voltage to be maintained across the components is 4.7V, power 5mW. Find the values for resistor and capacitor Homework Equations (Below) The Attempt at a Solution I found the resistance by...