 Capacitors deviate from the ideal capacitor equation in a number of ways. Some of these, such as leakage current and parasitic effects are linear, or can be assumed to be linear, and can be dealt with by adding virtual components to the equivalent circuit of the capacitor. The usual methods of network analysis can then be applied. In other cases, such as with breakdown voltage, the effect is non-linear and normal (i.e., linear) network analysis cannot be used, the effect must be dealt with separately. There is yet another group, which may be linear but invalidate the assumption in the analysis that capacitance is a constant. Such an example is temperature dependence. Finally, combined parasitic effects such as inherent inductance, resistance, or dielectric losses can exhibit non-uniform behavior at variable frequencies of operation. COUNT 5
QSN1 What characteristic can leakage current and parasitic effects be assumed to have in the equation for a realistic capacitor? ANS1 can be assumed to be linear QSN2 What sort of components can be added to the equivalent circuit of a capacitor in order to deal with leakage current and parasitic effects? ANS2 virtual components QSN3 Upon dealing with leakage current and parasitic effects in a realistic model of a capacitor, what sort of methods can then be applied? ANS3 The usual methods of network analysis QSN4 What sort of analysis cannot be used in cases of voltage breakdown in modelling a capacitor? ANS4 normal (i.e., linear) network analysis cannot be used QSN5 What causes the assumption of constant capacitance to fail even if the effect is linear in nature? ANS5 temperature dependence