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

When analyzing circuits using superposition theorem or Norton/Thevenin equivalents, we often need to "turn off" or "neglect" independent sources.
Neglecting a voltage source: An ideal voltage source maintains a constant voltage across its terminals, regardless of the current flowing through it. To "turn off" or neglect an ideal voltage source means to set its voltage to zero. A zero-voltage source is equivalent to a short circuit (a wire with zero resistance). Therefore, the terminals across the voltage source should be short-circuited. 
Neglecting a current source: An ideal current source maintains a constant current, regardless of the voltage across its terminals. To "turn off" or neglect an ideal current source means to set its current to zero. A zero-current source is equivalent to an open circuit (a break in the circuit, allowing no current to flow). Therefore, the terminals across the current source should be open-circuited. Based on this principle, for a voltage source to be neglected, its terminals should be short-circuited.