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Topic: Capacitance


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  Capacitance - Wikipedia, the free encyclopedia
The SI unit of capacitance is the farad (F).
In electrical circuits, the term capacitance is usually a shorthand for the mutual capacitance between two adjacent conductors, such as the two plates of a capacitor.
Stray capacitance is often encountered in amplifier circuits in the form of "feedthrough" capacitance that interconnects the input and output nodes (both defined relative to a common ground).
en.wikipedia.org /wiki/Capacitance   (1201 words)

  
 Capacitance
Capacitance is a property of a circuit in which energy may be stored in the form of an electric field.
The cover is marked with the capacitance and working voltage, and a fl ring is usually printed around one end to mark the terminal which is connected to the outermost layer of the foil.
Generally, the capacitance of a replacement capacitor should be within 10 to 20% of the capacitance of the original.
www.heirloomradio.com /capacitance.htm   (1316 words)

  
 6.6 The MOS Capacitance   (Site not responding. Last check: 2007-10-16)
The capacitance of an MOS capacitor is obtained using the same assumptions as in the analysis in section 6.5.
The flatband capacitance of the MOS structure at flatband is obtained by calculating the series connection of the oxide capacitance and the capacitance of the semiconductor, yielding:
Shown are, from top to bottom, the low frequency capacitance measured in the presence of ambient light (top curve), the low frequency capacitance measured in the dark, the high frequency capacitance measured in the presence of ambient light and the high frequency capacitance measured in the dark (bottom curve).
ece-www.colorado.edu /~bart/book/moscapc.htm   (1775 words)

  
 Semiconductor variable capacitance element - Patent 4816894
A variable capacitive element as claimed in claim 10; wherein the terminal electrode comprises a diffusion region formed in the semiconductor substrate adjacent to the depletion region under the floating electrode so that the diffusion region is capacitively strongly coupled to the floating electrode through the insulating film.
In this semiconductor variable capacitance element, a depletion layer or capacitive region 24 formed in a surface region of the semiconductor substrate 21 which is located under the floating electrode 23 is controlled by a potential generated at the floating electrode 23 by the electric charge accumulated in the floating electrode 23.
Since the capacitance electrode 12 of the conventional semiconductor variable capacitance element is connected directly to an external circuit, a bias voltage which is generated in the external circuit is applied directly to the capacitance electrode 12.
www.freepatentsonline.com /4816894.html   (1853 words)

  
 Capacitance
Capacitance is a physical property of the capacitor and does not depend on circuit characteristics of voltage, current, and resistance.
A given capacitor always has the same value of capacitance (farads) in one circuit as in any other circuit in which it is connected.
The third factor affecting capacitance is the DIELECTRIC CONSTANT of the insulating material between the plates of a capacitor.
www.sayedsaad.com /fundmental/11_Capacitance.htm   (1450 words)

  
 RF/Capacitance Level Instrumentation
Capacitance level detectors are also referred to as radio frequency (RF) or admittance level sensors.
The capacitance unit is the farad, defined as the potential created when a one-volt battery connected to a capacitor causes the storage of one coulomb of electric energy.
A pico-farad is one trillionth of that, and the sensitivity of an accurate capacitance detector is 0.5 pF.
www.omega.com /literature/transactions/volume4/T9904-13-RF-CAP.html   (2194 words)

  
 Capacitance   (Site not responding. Last check: 2007-10-16)
Capacitance is one of the most important applications of electrostatics to technology.
The unit of capacitance is the farad: 1 F = 1 C/V. The capacitance is numerically equal to the amount of charge (in coulombs) that has to be added to both conductors in order to change the potential difference by one volt.
The capacitance depends on the size and shape of the bodies, the spacing between them, and the material that fills that space, but it does not depend on the charge or the potential difference.
www4.ncsu.edu /~mowat/H&M_WebSite/Capacitance/Capacitance.html   (1224 words)

  
 Membrane Capacitance Changes Associated with Particle Uptake during Phagocytosis in Macrophages -- Holevinsky and ...
Membrane capacitance decreases from 71 to 65 pF.
Sharp decreases in capacitance presumed to be due to particle uptake are indicated by the arrows.
The upper traces show stepwise increases in capacitance occurring in the phagocytic cells after stimulation with latex particles at 37°C. Capacitance "flicker" as seen in A, or transient decreases in capacitance of relatively short duration, were absent from the exocytotic records as seen in B.
www.biophysj.org /cgi/content/full/75/5/2577   (5502 words)

  
 4.6 Capacitance to Voltage
Since voltage and capacitance are inversely proportional, this is useful when small values of capacitance are to be measured.
When one is dealing with larger values of capacitance the voltages resultant from a practical amount of charge are too small to be useful, and hence other methods must be used.
Capacitance can be measured in the same two ways discussed previously for measuring resistance - a voltage divider or a bridge circuit.
ccrma.stanford.edu /CCRMA/Courses/252/sensors/node18.html   (562 words)

  
 Capacitance Explained | Quantum Research Group
Capacitance is the ability of an object or surface to store an electrical charge.
Capacitance is analagous to the ability of a jar to hold a fluid.
While older capacitance sensing technology can monitor changes in capacitance, QProx™ is superior at ignoring huge amounts of background capacitance automatically; this is one of the things that gives it the amazing ability to 'turn anything (well, almost) into a sensor'.
www.qprox.com /background/capacitance.php   (1296 words)

  
 What is capacitor? - a definition from Whatis.com - see also: capacitance   (Site not responding. Last check: 2007-10-16)
The capacitance is directly proportional to the surface areas of the plates, and is inversely proportional to the separation between the plates.
Capacitance also depends on the dielectric constant of the substance separating the plates.
The standard unit of capacitance is the farad, abbreviated F.
whatis.techtarget.com /definition/0,,sid9_gci211742,00.html   (280 words)

  
 Miller Capacitance
The Miller capacitance in a triode tube is equal to the plate-to-grid capacitance multiplied by a factor equal to the stage gain plus one.
The majority of the input capacitance of a triode stage is made up of the combination of the grid-to-cathode capacitance, plus the Miller capacitance formed by the grid-to-plate capacitance multiplied by the stage gain plus one.
Since the Miller capacitance forms a lowpass filter in conjunction with the output resistance of the previous stage, it can be used as a "free" lowpass filter, thus saving the cost and trouble of adding a capacitor or RC network in the amplifier when a tailored frequency response is desired.
www.aikenamps.com /MillerCapacitance.html   (955 words)

  
 Capacitance
All the current we are measuring is thus capacitative.
The capacitance before the depolarization was about 14pF and increased by about 400fF in response to the depolarization.
Since all membranes have the same capacitance per unit area and since we know the diameter of the synaptic vesicles, we can calculate that about 500 vesicles fused at each synaptic body in response to this stimulus.
www.neurobio.ucla.edu /~felixs/capacita.htm   (565 words)

  
 capacitance
Capacitance is measured either by determining its reactance to a particular frequency AC voltage, or the time-constant of an R-C circuit it's part of.
It has become common to extend this definition (to the capacitance of a pair of conductors with equal and opposite charges on them) to the popular version of "charge per unit voltage".
So really, the capacitance of a conductor is the charge on it when it is maintained at 1 volt, and all the other conductors are grounded.
www.physicsforums.com /showthread.php?p=408717   (590 words)

  
 WHAT IS CAPACITANCE?   (Site not responding. Last check: 2007-10-16)
Capacitance exists between power transmission lines and ground resulting in additional current, and hence, power loss in the lines.
The total applications for capacitance is growing continuously and is limited only by the imagination of the industry.
Capacitance is used for safety such as warning people from entering a dangerous area (the person changes the K).
www.arjayeng.com /papers/CAPACITANCE.htm   (1650 words)

  
 Capacitance Probes
It works on the capacitance principle ie it measures the change in capacitance of the soil depending on the moisture level, as there is a large difference in the dielectric constant of soil, air and water.
The capacitance field generated between the two metal plates of the sensor extends beyond the PVC access tube into the surrounding soil.
The capacitance field is affected by the dielectric constant of the material the field passes through.
www.microirrigationforum.com /new/archives/cap.html   (2148 words)

  
 Numerical Analysis of Potential and Capacitance
The capacitance of a conducting body is defined as C = q / V, where q is the amount of charge on the body, and V is the potential of the body relative to some reference.
If you are interested in reading the step-by-step derivation of the capacitance, along with an exploration of what we mean when we say ``capacitance,'' then you can download the full 23-page paper, in postscript format.
Thus, as the equipotentials approach ellipsoids, the capacitance approaches a constant value that is independent of further increases in plate distance.
www.ttc-cmc.net /~fme/captance.html   (1927 words)

  
 CAPACITANCE
Given the dielectric constant and the area of and the distance between the plates of a capacitor, solve for capacitance.
Calculate the value of total capacitance in a circuit containing capacitors of known value in parallel.
CAPACITANCE is similar to inductance because it also causes a storage of energy.
www.tpub.com /neets/book2/3.htm   (1026 words)

  
 WIMA
A capacitor is measured by the size of its capacitance.
A capacitance is the electric capacity of a capacitor, i.e.
The capacitance is 1 farad when a current of 1 ampere flows for one second with the applied voltage of 1 V. The stored charge Q is proportional to the applied voltage U. The proportional factor C is the capacitance of the capacitor
www.wima.com /EN/capacitance.htm   (80 words)

  
 Sensors / Detectors: Capacitance Sensors
The capacitance between the two tubes increases as the level of the liquid rises.
The capacitance of a pair of wires (or a wire to a shield) is directly proportional to the length of the wire.
Solve Low frequency cutoff problems in capacitive sensors: 11/28/02 EDN Design Ideas / (added 1/05) One of the first problems a capacitive-sensor analog designer must face is the low-frequency cutoff.
www.discovercircuits.com /S/s-capacitance.htm   (936 words)

  
 Predictive capacitance layout method for integrated circuits - Patent 5367469
The method of claim 1, wherein predictive capacitance values are supplied for all nets of the circuit layout, and all of the predictive capacitance values are used as layout design constraints.
In fact, the actual capacitances may exceed the predicted values even if the majority of the nets in a circuit have capacitances that are substantially smaller than their predicted values.
To begin placing and routing cells within a layout, the estimated capacitance (or wire length) values for an initial circuit layout is compared with the predictive capacitance or maximum wire length values for that net, thereby ensuring that the predictive capacitance or maximum wire length value is not exceeded.
www.freepatentsonline.com /5367469.html   (3486 words)

  
 Capacitor - Wikipedia, the free encyclopedia
In SI units, a capacitor has a capacitance of one farad when one coulomb of charge causes a potential difference of one volt across the plates.
The capacitance is proportional to the surface area of the conducting plate and inversely proportional to the distance between the plates.
Also significant is that the impedance is inversely proportional to the capacitance, unlike resistors and inductors for which impedances are linearly proportional to resistance and inductance respectively.
en.wikipedia.org /wiki/Capacitor   (3757 words)

  
 4.5 The p-n junction capacitance   (Site not responding. Last check: 2007-10-16)
The capacitance associated with the charge variation in the depletion layer is called the junction capacitance, while the capacitance associated with the excess carriers in the quasi-neutral region is called the diffusion capacitance.
The junction capacitance is calculated using the expression for the parallel plate capacitance.
A capacitance versus voltage measurement can be used to obtain the built-in voltage and the doping density of a one-sided p-n diode.
ece-www.colorado.edu /~bart/book/pncap.htm   (346 words)

  
 RCA SelectaVision VideoDisc FAQ
Capacitance can be defined as the ability of two adjacent conductors to store electric charge, and in the CED system these adjacent conductors are the carbon-loaded disc and the thin titanium electrode deposited on the diamond stylus.
The mathematical formula for capacitance contains several variables, but with the CED system these variables are all nearly constant except one-- the distance between the electrode and the surface of the disc immediately under it.
Thomas Stanley of RCA Laboratories suggested in 1959 that video could be stored capacitively on a vinyl disc if a means could be found to mold sufficiently small signal elements in the surface of the vinyl.
www.cedmagic.com /home/cedfaq.html   (12062 words)

  
 Capacitance
Capacitance is typified by a parallel plate arrangement and is defined in terms of charge storage:
As can be seen from the diagram, that constrains the charge on the two capacitors to be the same in a DC situation.
This charge Q is the charge you get by calculating the equivalent capacitance of the series combination and multiplying it by the applied voltage V. You store less charge on series capacitors than you would on either one of them alone with the same voltage!
hyperphysics.phy-astr.gsu.edu /hbase/electric/capac.html   (166 words)

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