Question

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

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

Answer 1

The correct option is D 150 and 15000

$v_c=3v$
$R_c=3000\Omega$
$B=100$
$I_c=\frac{V_c}{R_C}=\frac{3}{3000}={10}^{-3}A$
$I_b=\frac{I_c}{B}=\frac{{10}^{-3}}{100}={10}^{-5}A$
$V_b=I_b{R}_b={10}^{-5}\times 2000=2\times {10}^{-2}V$
voltage gain $=\frac{V_c}{V_b}=\frac{3}{2\times {10}^{-2}}=150$
Power gain = B \times voltage gain
$=100\times 150$
$15000$