When a BJT is operating in linear region?

Explanation:

Operation of BJT in Linear Region

Definition: A Bipolar Junction Transistor (BJT) operates in the linear region (also known as the active region) when it functions as an amplifier. In this region, the transistor is neither fully "on" (saturation) nor fully "off" (cutoff). The active region is characterized by specific biasing conditions of the junctions within the BJT.

Biasing Conditions:

• Base-Emitter (B-E) Junction: The B-E junction is forward biased, meaning the voltage at the base is higher than the voltage at the emitter by at least the threshold voltage (approximately 0.7V for silicon BJTs).
• Base-Collector (B-C) Junction: The B-C junction is reverse biased, meaning the voltage at the base is lower than the voltage at the collector.

These biasing conditions allow the transistor to act as an amplifier by controlling the flow of current between the collector and emitter terminals based on the input signal applied to the base terminal.

Correct Option Analysis:

The correct option is:

Option 1: B-E junction is forward biased, and B-C junction is reverse biased.

This option correctly describes the biasing conditions required for a BJT to operate in the linear region. The forward biasing of the B-E junction ensures that the transistor is "on," while the reverse biasing of the B-C junction prevents the transistor from entering saturation. Together, these conditions enable the transistor to function as an amplifier