Hi,
Why Thevenin network is independent of any external excitation?
Please see bellow picture.
In the picture a, we want to v in terms of i and to do so we can apply an exciatation source such as voltage or current source into this terminals and then find relationship between v and i.
In the picture the author has chosen a current source. Could you explain why we can do that, I mean that to why Thevenin network is independent of any external excitation?