Let us talk about source transformation technique
A voltage source can be represented as a current source. Similarly, a current source can be represented as a voltage source
We normally do these to solve various circuit problems. A voltage source is equivalent to a current source and vice versa if they produce equal
values of load current and load voltage when connected to the load
They should also provide the same open circuit voltage and short circuit current
Suppose a voltage source has terminal voltage Vs at open circuit condition
The internal resistance of the source is Rse. Now the terminals of the source are short circuited
Hence, current supplied by the source would be Vs by Rse and let us consider it is Is
Now consider a current source which gives the same current Is at short circuit condition
If this short circuit current flow through the resistance is parallely connected with
the ideal current source, it will give same voltage drop Vs. So internal resistance of voltage source would be connected in parallel with ideal current
source to get equivalent current source of the voltage source. And similarly, the parallel internal resistance of the current source would be connected in
series with voltage source as internal resistance to get equivalent voltage source of the current source
Hope you understood the technique. Thank you. Thank you. Thank you.