Semiconductor Electronics Materials Devices and Simple Circuits - Result Question 65
67. 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 :
(a) $0.1 V$
(b) $1.0 V$
(c) $1 mV$
(d) $10 mV$
[2012]
Show Answer
Answer:
Correct Answer: 67. (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 $(V_i)$
$V_i=R_B I_B=1 \times 10^{3} \times 10^{-5}=10^{-2} Volt$
$V_i=10 mV$
