Question

The current gain of a transistor (common emitter type) is $100$, if the base current changes by $10\mu \text{A}$. What is the change in collector current?

• A. $\text{0.2 mA}$
• B. $\text{2 mA}$
• C. $\text{1 mA}$
• D. $\text{0.5 mA}$

Answer 1

The correct option is C $\text{1 mA}$

Given:
This transistor is common emitter type.

Current gain, $\beta =100$

Change in base current, $\Delta I_B=10\mu \text{A}={10}^{-5}\text{A}$

Change in collector current $\Delta I_C=?$

We know, $\beta =\frac{\Delta I_C}{\Delta I_B}$

$\Rightarrow \Delta I_C=\beta \Delta I_B=100\times {10}^{-5}={10}^{-3}A=1\text{mA}$

Hence, $\left(C\right)$ is the correct answer.

$\begin{array}{c}\text{Why this question?}\\ \text{Caution: It is very important to find out}\\ \text{the configuration or modes of operation}\\ \text{of transistor and then use the formula of}\\ \text{current gain for it.}\end{array}$