Question

In a common base transistor circuit, the current gain is 0.98. The current gain of common emitter transistor circuit is

• A. $0.2$
• B. $98$
• C. $20$
• D. $49$

Answer 1

The correct option is D $49$

In a common base transistor, current gain is given by,

$\beta =\frac{\Delta I_C}{\Delta I_B}=0.98$

The current gain of the common emitter transistor,

$\alpha =\frac{\Delta I_C}{\Delta I_E}$

$\alpha =\frac{\beta }{1-\beta }$

$\alpha =\frac{0.98}{1-0.98}=49$

$\alpha =49$

The correct option is D.