Voltages in Supernode: Shafia Needs Help!

[Shafia Zahin]

Hello Guys,
I have a problem in understanding Nodal Analysis with Voltage Sources.It says that a supernode has no voltage of its own.But I can't understand why?
Again,one more question,it says that there is no way of knowing the current through a voltage source in advance and that's why we have to use both KCL and KVL in case of a supernode.But what if the internal resistance of the voltage source is given?then we can know the current through it easily, or can't we?
I'm so confused,please help..
Shafia.

 

[anorlunda]

Ideal voltage sources have no internal resistance. If you are modeling a real life voltage source, use an ideal voltage source in series with an external resistance.