Electronics Engineering (ELEX) Board Practice Exam

Which of the following factors primarily concerns the stability of the voltage in a circuit?

1. Output impedance

2. Frequency of operation

3. Input voltage

4. Ambient temperature

The correct answer is: Output impedance

The stability of voltage in a circuit is primarily influenced by output impedance. Output impedance refers to the resistance faced by the output of a device or component when it attempts to drive a load. A low output impedance is crucial for maintaining voltage levels across varying load conditions. When the output impedance is low, the circuit can deliver current without significant voltage drop, ensuring that the voltage remains stable even when the load varies. Conversely, a high output impedance can result in fluctuations in the output voltage under load changes, making the circuit less stable. Other factors like frequency of operation, input voltage, and ambient temperature have their roles, but they do not directly determine the stability of voltage to the extent that output impedance does. Frequency, for instance, affects how components respond in AC circuits, while input voltage influences the overall operating range. Ambient temperature can also affect circuit performance but is more related to component characteristics and their thermal behaviors rather than directly stabilizing the output voltage.