A common emitter transistor amplifier has a current gain of 50 . If the load resistance is $4 \mathrm{k}…
A common emitter transistor amplifier has a current gain of 50 . If the load resistance is $4 \mathrm{k} \Omega$ and input resistance is $500 \Omega$, the voltage gain of the amplifier is
$100$
$200$
$300$
$400$
Solution
$
\begin{aligned}
\beta=50, R_L=4 \mathrm{k} \Omega & =4000 \Omega \\
R_i & =500 \Omega \\
\beta & =\frac{I_c}{I_b}
\end{aligned}
$
Voltage gain of amplifier
$
\begin{aligned}
& =\frac{\text { output voltage }}{\text { input voltage }}=\frac{I_c \times R_L}{I_b \times R_i} \\
& =\beta\left(\frac{R_L}{R_i}\right)=\frac{50 \times 4000}{500}=400
\end{aligned}
$