Question

For a voltage source to be neglected, the terminals across the source should be

• A. \( \text{replaced by an inductor} \)
• B. \( \text{short-circuited} \)
• C. \( \text{replaced by some resistance} \)
• D. \( \text{open circuited} \)

Hint:

Remember the rule for turning off independent sources in circuit analysis (e.g., for superposition, Thevenin/Norton equivalent circuits):

• Voltage Source Replace with a short circuit} (0V).
• Current Source Replace with an open circuit} (0A).

This allows you to analyze the contribution of other sources or determine equivalent resistances.

Answer 1

The Correct Option is B

The question asks about how to neglect a voltage source in circuit analysis.

1. Understanding the Concepts:

- Neglecting a Voltage Source: When using techniques like superposition, it is sometimes necessary to "turn off" or neglect a voltage source. To do this, the voltage source is replaced with its internal resistance. For an ideal voltage source, the internal resistance is zero. 
- Short Circuit: A short circuit is a path of zero resistance between two points in a circuit. 
- Open Circuit: An open circuit is a break in the circuit, resulting in infinite resistance.

2. Analyzing the Options:

- Replaced by an inductor: Replacing a voltage source with an inductor does not turn off the source. 
- Short-circuited: Replacing a voltage source with a short circuit (zero resistance) effectively makes the potential difference across those terminals zero, thus "neglecting" the voltage source. 
- Replaced by some resistance: Replacing a voltage source with some arbitrary resistance does not completely eliminate the source's effect. 
- Open circuited: Replacing a voltage source with an open circuit would completely break the circuit.

Final Answer:

For a voltage source to be neglected, the terminals across the source should be short-circuited.