This is another useful theorem used in simplifying complex/linear circuits just like Thevenin’s Theorem. The main difference between Thevenin’s theorem and Norton’s theorem is that, Thevenin’s theorem provides an equivalent voltage source and an equivalent series resistance, while Norton’s theorem provides an equivalent Current source and an equivalent parallel resistance.
Norton’s Theorem may be stated as:
It is possible to simplify any complex circuit/linear circuit with Current and Voltage source with an equivalent circuit containing a single Current Source IN and RN connected in parallel to a load.
Simple Steps To Solve Electric Circuit By Norton’s Theorem
1. Short the load resistor
2. Calculate the Short Circuit Current. This is the Norton Current (I N )
3. Short Voltage Sources, open load resistor and calculate the Open Circuit Resistance. This is the Norton Resistance (R N )
4. Now, Redraw the circuit with the calculated short circuit Current (I N ) in Step (2) as current Source and the calculated open circuit resistance (R N ) in step (3) connected in parallel to the load resistor that was short in Step (1). This is the Equivalent Norton Circuit of that Linear Electric Network or Complex circuit which had to be simplify and solved.
5. Finally find the Load current and Load Voltage across Load Resistor by using the Current divider rule or this formula:
Find the current flowing through and Voltage across the load resistor in the circuit below by using Norton’s Theorem.
Short the load circuit
Calculate the Short Circuit Current.
Using Current Divider Rule
( Resistor 6 and 3 are in parallel and in series to resistor 2)
Short Voltage Sources, open load resistor and calculate the Open Circuit Resistance. This is the Norton Resistance (R N )
….calculation of this, is started from the direction of the arrow.
Redraw the circuit with the calculated short circuit current.
Finally using this formula
From Ohm’s Law:
You will get the same answer as above if you solve the circuit by using Thevenin’s Theorem