Question

For a common emitter amplifier, current gain is $60$. If the emitter current is $6.6mA$ the collector current is :

• A. $0.108mA$
• B. $6.492mA$
• C. $1.1mA$
• D. $3.3mA$

Answer 1

The correct option is B $6.492mA$

Given that:
$\beta =60$
$I_e=6.6mA$
For transistors,
$\alpha =\frac{\beta }{1+\beta }$

$\alpha =\frac{60}{1+60}=\frac{60}{61}=0.9836$

Also,

$\alpha =\frac{I_c}{I_e}$

$I_c=\alpha I_c=\left(0.9836\right)\left(6.6\right)=6.49176\approx 6.492mA$