Forward Active Mode of an NPN Transistor: Identify the correct bias conditions for an n–p–n transistor operating in the forward active region.

Introduction / Context:
BJT operation depends on proper biasing of junctions. Forward active mode is the most important for amplification purposes.

Given Data / Assumptions:

• Device: NPN transistor.
• Bias conditions needed: forward-bias base–emitter, reverse-bias base–collector.

Concept / Approach:

For forward active mode: base–emitter junction must be forward biased (VB > VE), and base–collector must be reverse biased (VC > VB).

Step-by-Step Solution:

Verification / Alternative check:

This is the standard textbook definition of forward active biasing for NPN transistors.

Why Other Options Are Wrong:

• Emitter positive w.r.t. base: would mean base–emitter reverse bias.
• Collector positive only w.r.t. base: incomplete without base–emitter condition.
• None of the above: incorrect, option C is correct.

Common Pitfalls:

• Mixing up biasing for PNP vs. NPN.
• Thinking only one junction condition is sufficient.

Final Answer:

base is positive with respect to emitter and collector is positive with respect to base