Noise refers to an unwanted signal or disturbance in a/an ______ device or instrument.

• A. electronic
• B. mechanical
• C. optical
• D. acoustic

Answer: (A)

Noise is an unwanted disturbance that contaminates an electrical signal in electronic devices and instruments. It arises from random electrical fluctuations, such as thermal noise in resistors, shot noise from discrete charge carriers, and flicker noise in semiconductors. These random fluctuations set the noise floor and limit how well a signal can be detected or measured. Although the term is also used in mechanical, optical, or acoustic contexts, in telecommunications and instrumentation the standard meaning is unwanted electrical activity within electronic equipment, making electronic the best fit for this blank.