Semiconductor Electronics Materials Devices and Simple Circuits - Result Question 67
«««< HEAD:content/english/neet-pyq-chapterwise/physics/semiconductor-electronics-materials-devices-and-simple-circuits/semiconductor-electronics-materials-devices-and-simple-circuits-result-question-67.md
69. The input resistance of a silicon transistor is $100 \Omega$. Base current is changed by $40 \mu A$ which results in a change in collector current by $2 mA$. This transistor is used as a common emitter amplifier with a load resistance of $4 K \Omega$. The voltage gain of the amplifier is :
======= ####69. The input resistance of a silicon transistor is $100 \Omega$. Base current is changed by $40 \mu A$ which results in a change in collector current by $2 mA$. This transistor is used as a common emitter amplifier with a load resistance of $4 K \Omega$. The voltage gain of the amplifier is :
3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/semiconductor-electronics-materials-devices-and-simple-circuits/semiconductor-electronics-materials-devices-and-simple-circuits—result-question-67.md (a) 2000
(b) 3000
(c) 4000
(d) 1000
[2012M]
Show Answer
Answer:
Correct Answer: 69. (a)
Solution:
- (a) Voltage gain $(A_V)=\frac{V _{\text{out }}}{V _{\text{in }}}=\frac{I _{\text{out }}}{I _{\text{in }}} \times \frac{R _{\text{out }}}{R _{\text{in }}}$
$A_V=\frac{2 \times 10^{-3}}{40 \times 10^{-6}} \times \frac{4 \times 10^{3}}{100}=2 \times 100=2000$
In a common-emitter amplifier, the voltage signal obtained across the collector and the emitter is $180^{\circ}$ out of phase with the input voltage signal applied across the base and the emitter. This is indicated in the equation for $A_V$ by its negative sign.
