Question

In a BJT, what is the primary consequence of the Early effect on the effective base width?

• A. The base width increases
• B. The base width decreases
• C. The base width remains constant
• D. The base width becomes zero

Hint:

Early Effect → Base-width modulation → Effective base width decreases

Answer 1

The Correct Option is B

Understanding the Question: The question asks how the "Early Effect" (base-width modulation) physically changes the width of the base in a Bipolar Junction Transistor.
Key Formulas and approach: The "effective" base width is the physical width of the base minus the width of the depletion regions at the junctions.
Detailed Solution:
Step 1: Bias conditions. In a BJT, the Collector-Base (CB) junction is reverse-biased.
Step 2: Depletion region growth. As the reverse bias voltage on the collector increases, the depletion region at the CB junction expands.
Step 3: Modulating the base. Because this depletion region grows into the base area, the "neutral" part of the base where carriers can travel becomes thinner.
Conclusion: The Early effect results in a decrease of the effective base width.