Topic: Network Theory
The Thevenin's equivalent circuit of the network shown in figure is across a-b is
- A. $1~\Omega$
- B. $2~\Omega$
- C. $3~\Omega$
- D. $4~\Omega$
Answer: B. $2~\Omega$
Explanation: For Thevenin's equivalent resistance, short the independent voltage source and connect a 1 V test source across terminals a-b. This yields $I_2 = 1/6 \text{ A}$, meaning the dependent source $2I_2 = 1/3 \text{ V}$. The current from the 1V source is $I_1 = I_2 + 2/3 = 1/6 + 1/3 = 1/2 \text{ A}$. The equivalent resistance $R_{th} = V_{test}/I_1 = 1 / (1/2) = 2~\Omega$.