Question

In a common emitter amplifier, the load resistance of the output circuit is $1000$ times the resistance of the input circuit. If $\alpha =0.98$, the voltage gain is

• A. $98000$
• B. $9800$
• C. $49000$
• D. $4900$

Answer 1

The correct option is C

$49000$

Step 1: Given:

Load resistance is $1000$ times input resistance.

Current gain $\alpha =0.98$

Step 2: Formula used

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

Voltage gain = $\beta \frac{R_l}{R_i}$

Step 3: Calculation of voltage gain

$\beta =\frac{0.98}{1-0.98}$

⇒ $\beta =49$

⇒ voltage gain = $49\times \frac{R_l}{R_i}$

⇒ voltage gain = $49\times 1000$

⇒voltage gain = $49000$

Hence, the correct answer is option C.