Network Theorems

Superposition Theorem:

The response in any element of linear, bilateral network containing more than one source is the sum of the responses produced by the sources, each acting independently.

Thevenin's Theorem:
Any combination of linear, bilateral circuit elements and active source, regardless of the connection or complexity, connected to a given load ZL, may be replaced by a simple two terminal network consisting of a single voltage source of VTh volts and a single impedance Zeq in series with the voltage source, across the two terminals of the load ZL.

Norton's Theorem:
Any combination of linear, bilateral circuit elements and active sources regardless of the connection or complexity, connected to a given load ZL can be replaced by a simple two terminal network consisting of a single current source of IN and a single impedance Zeq in parallel with it, across the two terminals of the load ZL.