Norton Theorem reduces any two port circuit to a Norton Resistor, a load resistor, and a current source in parallel. Where Thevenin Theorem incorporates voltage source in series.

According to Thevenin Theorem, a complex circuit is reduced to two resistor network, Thevenin Resistor, and Load resistor and a Thevenin Voltage source to avoid redundant computation to analyze a frequent changing resistor.

Resistors are said to be parallel if there is only one path for the flow of current. The total resistance in parallel is less than the individual resistors in parallel.

Fundamentals of Electric Circuits by Charles C. Alexandar and Mathew N. O. Sadiku is a textbook for electrical circuit analysis and design from beginner to advanced level.

Gustav Kirchhoff was a German physicist, who presented two laws; Kirchhoff’s Current Law (KCL) and Kirchhoff’s Voltage Law (KVL). Ohm law is a very basic one, which may not be sufficient to analyze a complex circuit.

Mesh current Analysis provide a procedure for electric circuit analysis using mesh current as the circuit variable. The mesh analysis makes use of Kirchhoff’s Voltage Law as a basic key to analyze the circuit.