Question

In a BJT, largest current flow occurs

• A. In the emitter
• B. In the collector
• C. In the base
• D. Through CB junction.

Hint:

BJT Current Relationship. \(I_E = I_B + I_C\). Typically \(I_C \gg I_B\). Therefore, \(I_E\) is the largest current, and \(I_B\) is the smallest.

Answer 1

The Correct Option is A

For a Bipolar Junction Transistor (BJT) operating in its active region, Kirchhoff's Current Law dictates that the emitter current (\(I_E\)) is the sum of the base current (\(I_B\)) and the collector current (\(I_C\)): $$ I_E = I_B + I_C $$ The base is very thin and lightly doped, so the base current \(I_B\) (required to control the transistor) is much smaller than the collector current \(I_C\) (the main output current)
Typical current gain \(\beta = I_C / I_B\) is large (e
g
, 50-500)
Since \(I_C\) is typically much larger than \(I_B\), their sum, \(I_E\), is always the largest of the three terminal currents
Current flows *through* junctions, but the largest *terminal* current is the emitter current