Question

In a common emitter amplifier, the load resistance of the output circuit is $800$ times the resistance of the input circuit. If $\alpha =$ 0.99, the voltage gain is

• A. $79200$
• B. $39600$
• C. $7920$
• D. $3960$

Answer 1

Answer: (A)

$79200$

Given that:
$R_L=800R_i$
$\alpha =0.99$

For transistors,
$\beta =\frac{\alpha }{1-\alpha }$

$\beta =\frac{0.99}{1-0.99}=99$

Now,
Voltage gain = $\beta \times$ Resistance gain

Voltage gain = $\beta \times \frac{R_L}{R_i}$

Voltage gain = $99\times \frac{800R_i}{R_i}$

Voltage gain = $79200$