I don't think there is any fancy conversion. The circuit is simply redrawn. In Figure 1, the top of R1 and C1 are connected together at the same node. In order to maintain the same potential at that node when that node is split up, an identical voltage source, Vi is used at the corresponding terminal of R1 and C1.
Re: How to convert the circuit of figure1 to that of figure2
When performing network reduction for a Thévenin or Norton model, note that:
- nodes with zero voltage difference may be short-circuited with no effect on the network current distribution,
- branches carrying zero current may be open-circuited with no effect on the network voltage distribution.
Re: How to convert the circuit of figure1 to that of figure2
In textbooks on electrical circuits the voltage sources are always regarded as
ideal - i.e. their internal resistance is 0 Ohms and can therefore source an infinite
current, if short-circuited.
Similarly ideal current sources have an infinite internal resistance. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/visource.html
In real life - if you add a voltage source - you increase the current capacity - the
load current is not affected.