Semiconductor Electronics Materials Devices And Simple Circuits Ques 75
75. In a $C E$ transistor amplifier, the audio signal voltage across the collector resistance of $2 $ $k \Omega$ is $2$ $ V$. If the base resistance is $1 $ $k \Omega$ and the current amplification of the transistor is $100$, the input signal voltage is :
[2012]
(a) $0.1$ $ V$
(b) $1.0$ $ V$
(c) $1 $ $mV$
(d) $10$ $ mV$
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Answer:
Correct Answer: 75.(d)
Solution:
- (d) From the figure,
The output voltage, across the load $R_C$
$V_0=I_C R_C=2$
The collector current $(I_C)$
$I_C=\frac{2}{2 \times 10^{3}}=10^{-3} $ $Amp$
Current gain $(\beta)$
$(\beta)$ current gain $=\frac{I_C}{I_B}=100$
$I_B=\frac{I_C}{100}=\frac{10^{-3}}{100}=10^{-5} $ $Amp$
Input voltage $(V_i)$
$V_i=R_B I_B=1 \times 10^{3} \times 10^{-5}=10^{-2}$ $ Volt$
$V_i=10 $ $mV$
BETA
