Question

The current gain $\alpha$ of a transistor in common-base mode is $0.995$. Its current gain $\beta$ in the common-emitter mode is

• A. 200
• B. 90.5
• C. 100
• D. 1.005

Answer 1

Answer: (A)

The relation between current gain of a common-base transistor $(\alpha )$ to that of current gain between a common-emitter transistor $(\beta )$ is
$\beta =\frac{\alpha }{1-\alpha }$
Given, $\alpha =0.995$
$\therefore$ $\beta =\frac{0.995}{1-0.995}=199\approx 200$