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The difference between a capacitor and a battery is that a capacitor can dump its entire charge in a tiny fraction of a second, where a battery would take minutes to completely discharge. That's why the electronic flash on a camera uses a capacitor — the battery charges up the flash's capacitor over several seconds, and then the capacitor dumps the full charge into the flash tube almost instantly. This can make a large, charged capacitor extremely dangerous — flash units and TVs have warnings about opening them up for this reason. They contain big capacitors that can potentially kill you with the charge they contain.

All actions are performed using these digits. This is essential in converting what happens in an electrical device into a form that the computer programs can use. Using what is known as logic, the computer system is able to interpret the state of the electrical devices based on the current and/or charge that is being used. Therefore, there are really only two states: on or off, which are interpreted as one of zero. Static RAM’s method of binary interpretation is based on the relative potential differences across the memory cell. This is why SRAM is said to remain static, because the charge never actually leaves the cell.

Conduction current is related to moving charge carriers electrons, holes, ions, etc. , while displacement current is caused by a time varying electric field. Carrier transport is affected by electric fields and by a number of physical phenomena such as carrier drift and diffusion, trapping, injection, contact related effects, impact ionization, etc. In general, capacitance is a function of frequency. At High Voltage electronic Components frequencies, capacitance approaches a constant value, equal to "geometric" capacitance, determined by the terminals' geometry and dielectric content in the device. A paper by Steven Laux presents a review of numerical techniques for capacitance calculation.

Capacitance is the capability of a material object or device to store electric charge. It is measured by the charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related notions of capacitance: self capacitance and mutual capacitance. : 237–238 An object that can be electrically charged exhibits self capacitance, for which the electric potential is measured between the object and ground.

The invention of the capacitor varies somewhat depending on who you ask. There are records that indicate a German scientist named Ewald Georg von Kleist invented the capacitor in November 1745. Several months later Pieter van Musschenbroek, a Dutch professor at the University of Leyden, came up with a very similar device in the form of the Leyden jar, which is typically credited as the first capacitor. Since Kleist didn't have detailed records and notes, nor the notoriety of his Dutch counterpart, he's often overlooked as a contributor to the capacitor's evolution. However, over the years, both have been given equal credit as it was established that their research was independent of each other and merely a scientific coincidence.

Historical texts use other, obsolete submultiples of the farad, such as "mf" and "mfd" for microfarad µF; "mmf", "mmfd", "pfd", "µµF" for picofarad pF. Stray capacitance between the input and output in amplifier circuits can be troublesome because it can form a path for feedback, which can cause instability and parasitic oscillation in the amplifier. It is often convenient for analytical purposes to replace this capacitance with a combination of one input to ground capacitance and one output to ground capacitance; the original configuration – including the input to output capacitance – is often referred to as a pi configuration. When the input to output gain is very large, the equivalent input to ground impedance is very small while the output to ground impedance is essentially equal to the original input to output impedance. The capacitance of nanoscale dielectric capacitors such as quantum dots may differ from conventional formulations of larger capacitors. In particular, the electrostatic potential difference experienced by electrons in conventional capacitors is spatially well defined and fixed by the shape and size of metallic electrodes in addition to the statistically large number of electrons present in conventional capacitors.

Benjamin Franklin worked with the Leyden jar in his experiments with electricity and soon found that a flat piece of glass worked as well as the jar model, prompting him to develop the flat capacitor, or Franklin square. Years later, English chemist Michael Faraday would pioneer the first practical applications for the capacitor in trying to store unused electrons from his experiments. This led to the first usable capacitor, made from large oil barrels. Faraday's progress with capacitors is what eventually enabled us to deliver electric power over great distances. As a result of Faraday's achievements in the field of electricity, the unit of measurement for capacitors, or capacitance, became known as the farad.