Series circuit definition

In the series two-component model circuit, there is no direct access to both components from the external terminals. Figure 9.2. Because the two components are in series, the current can be externally controlled, but not the voltage division. Accordingly, a constant amplitude current i is applied across the model series circuit, and the voltage v is measured. The impedance Z has a direct relationship with a series R-C circuit, because the real part Z is R, and the imaginary part Z" is X = — l/wC. The series values are measured because it is proportionality between impedance Z and measured v. i is the independent reference sine wave, with zero phase shift per definition, and therefore here is designated as a scalar ... 

Fig. 8.19. Series/parallel equivalent circuit that can be used to model PEIS response (see text for definition of components).

Galvanometer with Variable Series Resistance.— As shown above, galvanometers, especially those of low resistance, are usually calibrated to read correctly for a definite line resistance. Suppose an indicator is desired for operation on a line of which the resistance changes from practically zero to 10 ohms. The instrument is calibrated to read correctly for a line resistance of 10 ohms. Located in the case of the galvanometer and in series with the line is a variable resistance from zero to 10 ohms. As the resistance of the line increases the variable resistance is decreased by manual adjustment so that the sum of the line resistance and the variable series resistance always equals 10 ohms. The dial of the variable resistance is graduated to read the amount of resistance cut out of the circuit. Hence, it should be set at the resistance of the line and couple. 

For simplicity we shall usually ignore C in the definition of eARC it may readily be included when needed. The eARC circuit element will, in fact, often appear in solid electrolyte equivalent circuits with C zero (or appearing elsewhere in the overall circuit). Then it is clear that the eARC function of Eq. (21) may be considered to represent a distributed (complex) capacitor. When t/r= 0, it involves an ordinary capacitor Co and resistor Ao in series, and when y/= 1, it involves Co in series with the capacitor Aq. These results are consistent with the behavior of the CPE alone. The CPE reduces to an ideal capacitor for 1 and to a resistor for y/=0. An example of the use of the eARC function for the analysis of a polycrystalUne sample is provided by the work of Casciola and Fabiani [1983]. 

The general shape of this impedance spectrum can then be modeled in terms of an equivalent circuit consisting for example of resistance and capacitance circuit elements combined in definite ways (series or parallel combinations) that can range from relatively simple to rather complex combinations, depending on the degree of complexity of the system under study. This correspondence between an impedance spectrum and an equivalent circuit is well-established in basic physics. These circuit elements reflect various physical features of the real electrochemical system under examination. For instance resistive elements can correspond to interfacial electron transfer processes or represent ionic or... 

The semi-enclosed fuse consists of a fuse wire, called the fuse element, secured between two screw terminals in a fuse carrier. The fuse element is connected in series with the load, and the thickness of the element is sufficient to carry the normal rated circuit current. When a fault occurs an overcurrent flows and the fuse element becomes hot and melts or blows . By definition a fuse is the weakest link in the circuit. Under fault conditions it will melt when an overcurrent flows, protecting the circuit conductors from damage. 

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