Question

For a common emitter connection, the values of constant collector current and base current are $5mA$ and $50$$\mu A$ respectively. The current transfer ratio $\left(\alpha \right)$ is :

• A. $0.89$
• B. $0.95$
• C. $0.99$
• D. $0.101$

Answer 1

Answer: (C)

$0.99$

$I_c=5mA$
$I_b=50\mu A=5\times {10}^{-2}mA$
The current gain in CE mode is
$\beta =\frac{I_c}{I_b}$
$\beta =\frac{5}{5\times {10}^{-2}}=100$

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

$\alpha =\frac{100}{101}=0.99$