Question

According to a graph drawn between the input and output voltages of a transistor connected in common emitter configuration, the region in which transistor acts as a switch is

• A. Cutoff or saturation region
• B. Active region
• C. Active or saturation region
• D. Cutoff or active region

Hint:

A simple way to remember the applications of transistor regions: - Switching: Uses the two extremes - Cutoff (OFF) and Saturation (ON). - Amplification: Uses the middle ground - Active region.

Answer 1

The Correct Option is A

Step 1: Understanding Transistor Switching Action: A transistor works as a switch by operating in two distinct states: 1. OFF State: Corresponds to the Cut-off region where the input voltage is low, the base current is zero, and the collector current is zero (Switch Open). 2. ON State: Corresponds to the Saturation region where the input voltage is high enough to drive maximum collector current with minimal voltage drop across the collector-emitter (Switch Closed).
Step 2: Conclusion: The active region is used for amplification, not switching. Therefore, for switching action, the transistor utilizes the Cutoff and Saturation regions.