JCECE Medical JCECE Medical Solved Paper-2015

  • question_answer
    The output resistance of a common emitter transistor amplifier, if the input resistance is \[200\,\Omega \] (\[\alpha =0.98\]and power gain is \[5\times {{10}^{6}},\]is)

    A) \[516\,k\Omega \]

    B)  \[216\,k\Omega \]

    C)  \[300\,k\Omega \]

    D)  \[416\,k\Omega \]

    Correct Answer: D

    Solution :

     We know that Voltage gain, \[\Delta V=\beta \frac{{{R}_{o}}}{{{R}_{i}}}\] Also, \[\beta =\frac{\alpha }{1-\alpha }=\frac{0.98}{1-0.98}=49\] \[\Delta V=(49)\left( \frac{{{R}_{0}}}{200} \right)\] Power gain AP\[\Delta P\] = Current gain \[(\beta )\times \]voltage gain \[(\Delta V)\] \[\Rightarrow \] \[5\times {{10}^{6}}=49\times 49\times \frac{{{R}_{o}}}{200}\] \[\Rightarrow \]\[{{R}_{e}}=\frac{5\times {{10}^{6}}\times 200}{49\times 49}=0.416\times {{10}^{6}}\simeq 416\,k\Omega \]


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