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Definition:A capacitor is an electronic device that is used to store electrical energy. They are only used to store the electrons and they are not capable of producing them.
Invention of the Capacitor:
There are many stories behind the invention of the capacitor. A German scientist named Ewald Georg von Kleist was known to invent the capacitor in November 1745. But, he did not have any detailed notes or records of his invention. So, he was given the credit for evolution of the capacitor. A few months later a Dutch professor called Pieter van Musschenbroek found a similar device called the Leyden Jar. Scientists approved this to be the first capacitor. After years, both the scientists have been given equal credit for the invention of the capacitor.
Working of a Capacitor:
A capacitor consists of two metal plates which are separated by a non-conducting substance or dielectric. Take a look at the figure given below to know about dielectric in a capacitor.Though any non-conducting substance can be used as a dielectric, practically some special materials like porcelain, mylar, teflon, mica, cellulose and so on. A capacitor is defined by the type of dielecric selected. It also defines the application of the capacitor.According to the size and type of dielectric used, the capacitor can be used for high-voltage as well as low-voltage applications.For applications in radio tuning circuits air is commonly used as the dielectric. for applications in timer circuits mylar is used as the dielectric. For high voltage applications glass is normally used. For application in X-ray and MRI machines, ceramic is mostly preferred.The metal plates are separated by a distance “d”, and a dielectric material is placed in-between the plates.
The dielectric material is the main substance that helps in storing the electrical energy.Definition of Capacitance:
There are mainly two concepts for defining capacitance. The electrical concept is given below.
Capacitance is said to be the capacitor’s storage potential. In other words, for an existing potential difference or voltage “V” across the plates, the capacitance is said to be the amount of charge “Q” stored in between the plates.Capacitance, C = Q/V
Physical concept of capacitance is that capacitance is defined by the physical characteristics of the two plates, such that the capacitance is equal to the ratio between the square area of a plate and the distance between the plates multiplied by the dielectric of the material in between the platesCapacitance, C = e0e A/d
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