ELECTRONIC DEVICES — Terminals on a BJT How many electrical terminals (external leads) does a standard BJT have?

Introduction / Context:
A Bipolar Junction Transistor (BJT) is a three-terminal device used for amplification and switching. Correctly identifying its terminals is essential for wiring and biasing in circuits.

Given Data / Assumptions:

• The device class is a standard discrete BJT.
• We are counting external connection points, not internal junctions.
• Package style (TO-92, TO-220, SOT-23) does not change the count.

Concept / Approach:
BJTs have three terminals: the emitter (E), base (B), and collector (C). Current flowing from emitter to collector is controlled by a small base current. Configurations like common-emitter, common-base, and common-collector refer to which terminal is shared between input and output.

Step-by-Step Solution:
Identify the functional parts: emitter, base, collector.Each corresponds to an external lead.Therefore, a BJT has exactly 3 terminals.

Verification / Alternative check:
Datasheets label pinouts with E, B, C in various orders depending on package. Circuit symbols also depict three distinct terminals.

Why Other Options Are Wrong:
1/2 — would not allow transistor action (need control and output paths).4/5 — extra leads apply to special devices or integrated packages, not a standard BJT.

Common Pitfalls:
Reversing emitter and collector leads when substituting transistors; always check the datasheet pinout.

Final Answer:
3