Question

In a common emitter transistor amplifier the audio signal voltage across the collector is $3\,V$. The resistance of collector is $3\, k\Omega$. If current gain is $100$ and the base resistance is $2\, k\Omega$, the voltage and power gain of the amplifier is :

• A. 15 and 200
• B. 150 and 15000
• C. 20 and 2000
• D. 200 and 1000

Answer 1

The Correct Option is B

To solve this problem, we need to calculate the voltage gain and power gain of the common emitter transistor amplifier.

Given Data:

• Audio signal voltage across the collector, \( V_c = 3 \, \text{V} \)
• Collector resistance, \( R_c = 3 \, \text{k}\Omega = 3000 \, \Omega \)
• Base resistance, \( R_b = 2 \, \text{k}\Omega = 2000 \, \Omega \)
• Current gain (beta), \( \beta = 100 \)

Step 1: Calculate the Voltage Gain ( \( A_v \) )

The voltage gain of a common emitter amplifier is given by the formula:

A_v = \beta \times \frac{R_c}{R_b}

Substitute the given values:

A_v = 100 \times \frac{3000}{2000}

A_v = 100 \times 1.5 = 150

Thus, the voltage gain of the amplifier is 150.

Step 2: Calculate the Power Gain ( \( A_p \) )

The power gain is given by:

A_p = A_v \times \beta

Substituting the known values, we get:

A_p = 150 \times 100 = 15000

Therefore, the power gain of the amplifier is 15000.

Conclusion:

The voltage and power gain of the amplifier are 150 and 15000, respectively. Therefore, the correct answer is:

150 and 15000.