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Home Electrical Fundamentals of Communication Capacitance  


CapacitanceThe definition of capacitance of most value in communication is^{1} "the property of an electric system comprising insulated conductors and associated dielectrics which determines, for a given rate of change of potential differences between the conductors, the displacement currents in the system. Thus in a system of two conductors only
where C is the capacitance, i the displacement current, and e the potential difference between the conductors." The usual units are amperes, farads, and volts per second. Equation 9 is in terms of instantaneous values. For steadystate effective values this equation can be written
In these equations I is the magnitude of the effective value of the current in amperes, E_{c} is the magnitude of the effective value of voltage across the condenser in volts, and f is in cycles per second. The voltage E_{C} lags the current I by 90°. This equation assumes that capacitance only exists in the circuit,


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