Question

The current gain of a transistor in common base and commom-emitter configurations called $\alpha$ and $\beta$ are related as

• A. $\alpha =\frac{\beta }{1+\beta }$
• B. $\beta =\frac{\alpha }{1-\alpha }$
• C. $\beta =\frac{1+\alpha }{\alpha }$
• D. both 1 & 2

Answer 1

The correct option is D both 1 & 2

$I_E=I_B+I_C$

$I_C=I_E-I_B$

$I_B=I_E-I_C$

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

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

Relationship between these will be

$\alpha =\frac{I_C}{I_E}=\frac{\beta }{1+\beta }$

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

Hence (d) option is correct