Question

The input resistance of a common emitter amplifier is $330\Omega$ and the load resistance is $5k\Omega$. A change of base current is $15\mu A$ results in the change of collector current by $1mA$. The voltage gain of amplifier is

• A. $1000$
  
• B. $10001$
  
• C. $1010$
  
• D. $1100$
  

Answer 1

The correct option is C $1010$

Given: $\Delta I_C=1mA={10}^{-3}A$

$\Delta I_b=15\mu A=15\times {10}^{-6}A$

$R_L=5k\Omega =5\times {10}^3\Omega$

$Ri=330\Omega$

The voltage gain of an amplifier

$A_r=\frac{\Delta I_C\times R_L}{\Delta I_b\times R_i}$

$=\frac{{10}^{-3}\times 5\times {10}^3}{15\times {10}^{-6}\times 330}\approx 1010$