Question

A transistor operating in a common base configuration has forward current gain factor, $\alpha=0.99 .$ If the emitter current changes by $1 \mathrm{~mA}$, then the changes in the base current will be : (a) $100 \mathrm{~mA}$ (b) $0.01 \mathrm{~mA}$ (c) $0.99 \mathrm{~mA}$ (d) $99 \mathrm{~mA}$

Name: Problem 28, Chapter 34: Arihant AIEEE Physics
Uploaded: 2021-09-08T15:17:15-08:00
Duration: 1 min 22 s
Channel: Ajay Singhal
Description: A transistor operating in a common base configuration has forward current gain factor, α=0.99 . If the emitter current changes by 1 mA, then the changes in the base current will be : (a) 100 mA (b) 0.01 mA (c) 0.99 mA (d) 99 mA

   A transistor operating in a common base configuration has forward current gain factor, $\alpha=0.99 .$ If the emitter current changes by $1 \mathrm{~mA}$, then the changes in the base current will be :
(a) $100 \mathrm{~mA}$
(b) $0.01 \mathrm{~mA}$
(c) $0.99 \mathrm{~mA}$
(d) $99 \mathrm{~mA}$

Arihant AIEEE Physics

D.B. Singh 2006 Edition

Chapter 34, Problem 28

Instant Answer

Solved by Expert Ajay Singhal

09/08/2021

Step 1

Mathematically, it can be represented as: \[\alpha = \frac{\Delta I_C}{\Delta I_E}\] Show more…

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A transistor operating in a common base configuration has forward current gain factor, $\alpha=0.99 .$ If the emitter current changes by $1 \mathrm{~mA}$, then the changes in the base current will be : (a) $100 \mathrm{~mA}$ (b) $0.01 \mathrm{~mA}$ (c) $0.99 \mathrm{~mA}$ (d) $99 \mathrm{~mA}$

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Key Concepts

Forward Current Gain (Alpha)

The forward current gain (?) in a common base configuration is defined as the ratio of the collector current (IC) to the emitter current (IE). Since ? is usually close to 1, it implies that most of the emitter current contributes to the collector current, with only a small fraction flowing into the base.

Current Relationships in Transistors

In any bipolar junction transistor, the emitter current (IE) is the sum of the collector current (IC) and the base current (IB). This relationship can be used to determine IB when a change in IE occurs, specifically using the equation IB = IE - IC = (1 - ?)IE.

Common Base Configuration

A transistor configuration where the base terminal is common to both the input and output circuits. It is characterized by the input being applied at the emitter and the output taken at the collector, with the base serving as a common reference point.

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