# Verify Thevenin and Nortan’s theorem

Aim:- To verify Thevenin’s theorem and Nortan’s theorem.

Apparatus Required:-

 S. No. Name of the Equipment Type Range Quantity 1. Electric Network Kit - - 1 2. Voltmeter MC 0 – 30V 1 3. Ammeter MC 0 – 100mA 1 4. Power Supply Regulated 0 – 30V 1

Theory:-

The Thevenin's theorem and Nortan's theorem are used to simplify a complicated network consisting of a number of sources, circuit elements and load.

Thevenin's theorem states that any two terminal linear network having a number of voltage current sources and resistances can be replaced by a simple equivalent circuit consisting of a single voltage source in series with a resistance, where the value of the voltage source is equal to the open circuit voltage across the two terminals of the network, and resistance is equal to the equivalent resistance measured between the terminals with all the energy sources are replaced by their internal resistances.

Norton's theorem states that any two terminal linear network with current sources, voltage. sources and resistances can be replaced by an equivalent circuit consisting of a current source in parallel with a resistance. The value of the current source is the short circuit current between the two terminals of the network and the resistance is equal to the equivalent resistance measured between the terminals with all the energy sources are replaced by their internal resistances.

Circuit Diagram:-

Procedure for Thevenin’s theorem:-

1.     Connect the circuit as per the given electrical network.

2.     Remove the lead resistance from network and turn on the supply.

3.     Find the Thevenin's resistance Rth.

4.     Measure the Thevenin's voltage Vth.

5.     Now measure the current in the load resistance directly.

6.     Theoretically find out the current in the load resistance.

7.     Verify that these two are equal.

Observation Table for Thevenin’s theorem:-

 S. No. V0(V) VTR(V) (T) VTR(V) (P) RTR(ohms) (T) RTR(ohms) (P) IL(mA) (T) IL(mA) (P) % Error 1. 6 4.852 4.823 121.309 123.7 4.327 4.292 0.808%

Calculation:-

VTh (Theoritical) = 121.309

RTh (Theoritical) = 4.852

% Error = 0.808 %

Procedure for Nortan’s theorem:-

1.     Connect the circuit as per the given electrical network.

2.     Remove the lead resistance from network and turn on the supply.

3.     Find the Nortan's resistance RN.

4.     Measure the Nortan's current IN.

5.     Now measure the current in the load resistance directly.

6.     Theoretically find out the current in the load resistance.

7.     Verify that these two are equal.

Observation Table for Nortan’s theorem:-

 S. No. V0(V) VTR(V) (T) VTR(V) (P) RTR(ohms) (T) RTR(ohms) (P) IL(mA) (T) IL(mA) (P) % Error 1. 8 1.6 1.1 217.3 227.1 4.2 4.15 1.190%

Calculation:-

RN = 217.31 ohms

I= 1.16 mA        ,   % Error = 1.190 %

Precautions:-

1.     All the connections should be neat clean and tight.

2.    Special care should be taken while selecting types and ranges of the meter for conducting open circuit test.

Conclusion :-

1.     The theoretical values and measured value of VTh and RTh and ITh are approximately equal hence Thevenin's theorem has been verified.

2.     The theoretical values and measured value of VN and RV and IN are approximately equal hence Norton's theorem has been verified.