1. Associate Professor, Dept. of Physics,
Norton’s Theorem By
Dr. Vaibhav Jain
Associate Professor, Dept. of Physics,
D.A.V (PG) College, Bulandshahr, U.P., India.

2. Objective of Lecture State Norton Theorem.
Demonstrate how Norton theorem can be used to simplify a circuit to one that contains three components: a power source, equivalent resistor, and load.

3. Norton’s Theorem
A linear two-terminal circuit can be replaced with an equivalent circuit of an ideal current source, IN, in series with a resistor, RN.
IN is equal to the short-circuit current at the terminals.
RN is the equivalent or input resistance when the independent sources are turned off.

4. Definitions for Norton’s Theorem
Open-circuit voltage Isc is the current, i, when the load is a short circuit (i.e., RL = 0W).

5. Definitions for Norton’s Theorem
Input resistance is the resistance seen by the load when IN = 0A.
It is also the resistance of the linear circuit when the load is an open circuit (RL = ∞W).

6. Steps to Determine IN and RN
Identify the load, which may be a resistor or a part of the circuit.
Replace the load with a short circuit .
Calculate ISC. This is IN.
Turn off all independent voltage and currents sources.
Calculate the equivalent resistance of the circuit. This is RTH.
The current through and voltage across the load in parallel with IN and RN is the load’s actual current and voltage in the originial circuit.

7. Source Conversion
A Thévenin equivalent circuit can easily be transformed to a Norton equivalent circuit (or visa versa).
If RTh = RN, then VTh = RNIN and IN = VTh/RTh

8. Value of Theorems Simplification of complex circuits.
Used to predict the current through and voltage across any load attached to the two terminals.
Provides information to users of the circuit.

9. Example #1
Find IN and RN

10. Example #1 (con’t) Calculation for IN
Look at current divider equation:
If RTh = RN= 1kW, then IN = 6mA

12. Source Transformation
Equations for Thévenin/Norton Transformations VTh = IN RTh IN = VTh/RTh RTh= RN

13. Summary Norton transformation is performed to:
Simplify a circuit for analysis
Allow engineers to use a voltage source when a current source is called out in the circuit schematic
Enable an engineer to determine the value of the load resistor for maximum power transfer/impedance matching.

14. Thank You