already on our list of simplifying techniques. We begin expanding this list
with source transformations. A source transformation, shown in Fig. 4.36,
allows a voltage source in series with a resistor to be replaced by a current
source in parallel with the same resistor or vice versa. The double-headed
arrow emphasizes that a source transformation is bilateral; that is, we can
start with either configuration and derive the other.
We need to find the relationship between vs and is that guarantees the
two configurations in Fig. 4.36 are equivalent with respect to nodes a,b.
Equivalence is achieved if any resistor RL experiences the same current
flow, and thus the same voltage drop, whether connected between nodes