(a) Figure 3-41 shows the Thévenin equivalent found in (a) and the two loads. When the load is a 10-kn resistor, the interface current is i (6)/ (9000 10.000) 0.3158 mA, and the power delivered to the load is i Ri 0.9973 mW. When the load is a 5-V source, the interface volt age and current are power to the load is vi 0.5555 mW. Since p 0 in the latter case, we see that the voltage source load is absorbing rather than delivering power. A practical example of this situation is a battery charger.
Caution: The Thévenin equivalent allows us to calculate the power delivered to a load, but it does not tell what power is dissipated the source circuit. For instance, if the load in Figure 3-40(e) is an open circuit, then no power is dissipated in the Thévenin equivalent since i 0. This does not mean that the power dissipated in the source circuit is zero, as we can easily see by looking back Figure 3-40(a). The Thévenin equivalent circuit has the same i v characteristic at the interface, but it does not duplicate the internal characteristics of the source circuit