Thevenin's theorem example : In the circuit of Figure, determine: a) Thevenin's equivalent circuit between A and B; b) power dissipated in a 4.5 ohm resistor placed between A and B.

 Question:

In the circuit of Figure, determine: a) Thevenin's equivalent circuit between A and B; b) power dissipated in a 4.5 ohm resistor placed between A and B.

Explanation:

Thevenin's theorem statement:

"Any linear circuit containing several voltages and resistances can be replaced by just one single voltage in series with a single resistance connected across the load" 

Steps to solve questions:

Step 1 : Remove load resistor or component concerned. 

Step 2 : Find thevenin's equivalent voltage Vth by using any suitable method. 

Step 3 : Find equivalent resistance Rth. 

Case 1 - if independent voltage source is present in a circuit then replace it by short circuit. 

Case 2 - if independent current source is present in a circuit then replace it by open circuit. 

Case 3 - if dependent source is present in a circuit then Rth can be obtained by taking ratio of open circuit voltage to short circuit current. 

Step 4 : Draw thevenin's equivalent circuit having single voltage source and resistance in series with load. 

Part (a) explanation:

Part (b) explanation:

Answers:

Part (a) answer: Vth = Vab = -10V, Rth = 0.5 ohm

Part (b): Power dissipated in 4.5 ohm = 18 W