Norton and Thevenin equivalents

These 2 theorems are essential in electrical engineering because with them you can simplify a circuit with just 2 components: a generator and a resistance.

TOPICS OF THE TUTORIAL:

Norton Theorem

Thevenin Theorem

Exercises

Norton Theorem:

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Any linear network of resistors and voltage or current sources can be replaced by an equivalent current source in parallel with a single resistor(often indicated with conductance for Norton and with resistance for Thevenin). This equivalent circuit retains the same behavior at the output terminals as the original circuit.

To find the Norton equivalent circuit: Step 1: “turn off” all the power sources(except those controlled):turn voltage source into short circuit and current source into open circuit.Calculate the equivalent resistance Step 2: Find the short-circuit current at the output terminals using KCL and KVL,considering equivalent terminal(terminals A and B in the exercises you will see) as short circuit

Actually there are also other methods to find Norton and Thevenin equivalent. You should practice with the one that you feel more comfortable and easy to understand.

Thevenin Theorem:

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Any linear network of resistors and voltage/current sources can be replaced by an equivalent voltage source in series with a single resistor.

Those equivalent circuits have the same behavior of orginal circuit.

The process to find this equivalent is the same of Norton process,but in the second point you have to consider equivalent terminal as an open circuit.Let’s see some practical examples:

Second exercise: