Question

Consider a linear active two-terminal network connected across terminals Y and Z. If the Thevenin equivalent resistance (\(R_{TH}\)) of this network is calculated to be 0 \(\Omega\), the network behaves essentially as an:

• A. Ideal Current Source
• B. Ideal Voltage Source
• C. Practical Voltage Source
• D. Open Circuit

Hint:

Remember the ideal source characteristics by their internal resistances: \begin{itemize} \item Ideal Voltage Source: \(R_{series} = 0 \, \Omega\) \item Ideal Current Source: \(R_{parallel} = \infty \, \Omega\) \end{itemize} This direct mapping helps in quickly solving such conceptual problems.

Answer 1

The Correct Option is B

Step 1: Understanding the Thevenin Model
According to Thevenin's Theorem, any linear active two-terminal network can be replaced by an equivalent circuit consisting of a voltage source \(V_{TH}\) in series with a resistance \(R_{TH}\).
Step 2: Analyzing Terminal Voltage
The voltage across the load \(R_L\) connected to terminals Y and Z is: \[ V_{YZ} = V_{TH} - I \cdot R_{TH} \] If the calculated \(R_{TH} = 0 \, \Omega\), the equation simplifies to \(V_{YZ} = V_{TH}\).
Step 3: Conclusion Based on Source Definitions
Since \(V_{YZ} = V_{TH}\) regardless of the magnitude of the current \(I\) flowing through the load, the terminal voltage is constant. This is the fundamental characteristic of an Ideal Voltage Source. If there were any non-zero \(R_{TH}\), the terminal voltage would drop as current increases, which is the behavior of a Practical Voltage Source.