Question

For a common emitter configuaration, if $\alpha$ and $\beta$ have their usual meanings, the incorrect relation ship between $\alpha$ and $\beta$ is: (2016 Mains off line)

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

Answer 1

Answer: (C)

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

$\begin{array}{c}\text{For a common emitter configuration ,}\\ \text{we know that}\\ \begin{array}{cc}\frac{1}{\alpha }& =\frac{1}{\beta }+1\\ \frac{1}{\alpha }=\frac{1+\beta }{\beta }& \\ \alpha =\frac{\beta }{1+\beta }& \end{array}\end{array}$