Verification of Thevenin’s Theorem

Experiment No.: 1

Experment Name:

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

Objective:

To verify Thevenin’s theorem.

Theory:

Thevenin’s theorem may be stated as follow, “The current flowing through a load resistance R_L connected across any two terminal A and B of a linear, active, bilateral network is given by V_oc/ (R_i+R_L) where V_oc is the open circuit voltage (i.e. voltage across the two terminals when R_L is removed) and R_i is the internal resistance of the network as viewed from back into the open circuited network from terminal A and B with all voltage sources replaced by their internal resistance (if any) and current sources by infinite resistance.”

Circuit Diagram:

Observation:

1. When load resistance (R_L) is attached/connected with the circuit then current flowing through it is I_L = 39.8 mA.
2. R_L is disconnected and measured the open circuit voltage, V_oc = 9.75 V viewing from the output terminal.
3. R_L is disconnected and voltage source is short circuit and measured the internal resistance of the circuit, R_i =137.3 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, I_L = 39.8 mA
5. A circuit (Thevenin’s equivalent circuit) is created with a voltage source (V_oc) = 9.75 V and series resistance (R_i) = 137.3 ohm, load resistance (R_L) = 100 ohm, then load current calculated is (I_L) = 39.8 mA.
6. Now measured load current is checked with calculated load current, which is merely same.

Thevenin’s Equivalent Circuit:

Calculation:

I_L = V_OC/(R_i+R_L)

Apparatus Used:

Sl. No.	Name of the apparatus	Specification	Quantity	Maker’s Name
1	DC Network Theorem Trainer Kit	230 V Input	1	M.E.W.
2	Digital Multimeter as ammeter	0-10 A	1	Akademika
3	Carbon Component Resistor	100 Ohm	1
4	DC Source	0-30 V	1	Sushama

Remarks:

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