**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:**

- When load resistance (R
_{L}) is attached/connected with the circuit then current flowing through it is**I**_{L}=**39.8 mA**. - R
_{L}is disconnected and measured the open circuit voltage,**V**viewing from the output terminal._{oc}= 9.75 V - R
_{L}is disconnected and voltage source is short circuit and measured the internal resistance of the circuit,**R**viewed from the output terminal._{i}=137.3 ohm - All resistances and volatge source is connected as per circuit and load current flowing through the load is measured,
**I**_{L}= 39.8 mA - 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**. - 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.