Discussion Forum

A transistor is used as a  common emitter amplifier with a load resistance 2 k $\Omega$ .The input resistance is 150 k $\Omega$ .Base current is changed by 20 $\mu$ A which results in a change in collector current by 1.5 mA. The voltage gain of the amplifier is 

Answer:

Explanation:

Given , load resistance (R_e)=2 k $\Omega$= 2 x 10³Ω

 Input  resistance (R_i)= 150 $\Omega$

 Change on collector current ($\triangle$ l_c)= 1.5 mA= 1.5 x 10^-3 A

Change in base current ($\triangle$ l_B)=20 $\mu$ A= 20 x 10^-6 A

 We know that

 Voltage gain=  $\frac{V_{o}}{V_{i}}=\frac{R_{o}\times\triangle l_{C}}{R_{i}\times\triangle l_{B}}$

= $\frac{2\times 10^{3}\times 1.5\times 10^{-3} }{150\times 20\times 10^{-6}}= \frac{3\times 10^{6}}{150\times 20}=1000$