Q180 / 200 · TS EAMCET 2002 · Physics

A common emitter transistor amplifier has a current gain of 50 . If the load resistance is $4 \mathrm{k} \Omega$ and input resistance is $500 \Omega$, the voltage gain of the amplifier is

  • A
    $100$
  • B
    $200$
  • C
    $300$
  • Correct answer
    D
    $400$

Solution

$$ \begin{aligned} \beta=50, R_L=4 \mathrm{k} \Omega & =4000 \Omega \\ R_i & =500 \Omega \\ \beta & =\frac{I_c}{I_b} \end{aligned} $$ Voltage gain of amplifier $$ \begin{aligned} & =\frac{\text { output voltage }}{\text { input voltage }}=\frac{I_c \times R_L}{I_b \times R_i} \\ & =\beta\left(\frac{R_L}{R_i}\right)=\frac{50 \times 4000}{500}=400 \end{aligned} $$

Hence, the correct answer is option: 'D'.

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