Why is the Thevenin's theorem important for circuit diagrams?
Thevenin's theorem can greatly simplify the analysis of current flow and apparent resistance in a circuit.
In a circuit containing multiple series and parallel connected components, including voltage and/or current sources and resistors, determining the current flowing and voltage level at a point in the circuit can be difficult, or even a complete mystery.
Thevenin's Theorem: Any combination of batteries and resistances with two terminals can be replaced by a single voltage source
This allows the current flowing at a point in the circuit to be calculated without knowing the voltages or currents at intermediate points in the circuit, which would otherwise be very difficult to do.
Thevenin's Theorem is often used in conjunction with Norton's theorem, which is the 'current source in parallel with a single resistor' equivalent.