As originally stated in terms of DC
resistive circuits only,
Thévenin's theorem holds that:
- Any linear electrical network with voltage and current sources and only resistances can be replaced at terminals A-B by an equivalent voltage source Vth in series connection with an equivalent resistance Rth.
- This equivalent voltage Vth is the voltage obtained at terminals A-B of the network with terminals A-B open circuited.
- This equivalent resistance Rth is the resistance obtained at terminals A-B of the network with all its independent current sources open circuited and all its independent voltage sources short circuited.