# Verification of Norton’s Theorem

Experiment No.: 2

Experiment Name:

Use Voltmeter, Ammeter to Determine Equivalent Circuit Parameter in a Given Circuit by
Applying Norton’s theorem.

Objective:

To verify Norton’s theorem.

Theory:

The Norton’s theorem may be stated as, “Any two terminal active containing voltage sources and resistance when viewed from its output terminals is equivalent to a constant current source and a parallel resistance. The constant current is equal to the current which would flow in a short circuit placed across the terminals and parallel resistance is the resistance of the network when viewed from these open circuited terminals after all voltage and current sources have been removed and replaced by their internal resistances.”

Circuit Diagram:

Observation:

1. When load resistance (RL) is attached/connected with the circuit then current flowing through it is IL = 40.8 mA.
2. RL is disconnected and shorted the load terminals and measured the short circuit current, Isc or Norton’s equivalent current, ISC = 70.87 mA.
3. RL is disconnected and voltage source is short circuit and measured the internal resistance of the circuit, Ri =135.9 ohm viewed from the output terminal.
4. All resistances and volatge source is connected as per circuit and load current flowing through the load is measured, IL = 40.8 mA
5. A circuit (Norton’s equivalent circuit) is created with a cuurent source (ISC) = 70.87 mA and parallel internal resistance (Ri) = 135.9 ohm, and parallel load resistance (RL) = 100 ohm, then load current calculated is (IL) = 40.8 mA.
6. Now measured load current is checked with calculated load current, which is merely same.

Norton’s Equivalent Circuit:

Calculation:

IL = IN . (Ri/(Ri+RL))

Apparatus Used:

Remarks:

The observational values and calculated values are nearly same. The difference between them is for instrumental and observational error. Neglecting this error, Norton’s theorem is verified posistively.

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