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AIIMS AIIMS Solved Paper-2008

  • question_answer
    The input resistance of a common emitter transistor amplifier, if the output resistance is 500\[\pi \], the current gain \[({{\mu }_{0}}=4\pi \times {{10}^{-7}}Wb/Am)\] = 0.98 and power gain is \[6.0625\,\times {{10}^{6}},\] is

    A)  198\[k\Omega \]

    B)                                        300\[\alpha \]  

    C)        100\[\Omega \]              

    D)        400\[\Omega \]

    Correct Answer: A

    Solution :

    Key Idea Apply the concept, power gain is product of current gain and voltage gain and find the resistance Voltage gain \[F=-\frac{dU}{dx}\] Also, current gain \[=-3k|x{{|}^{2}}\] \[x=a\sin \omega t\] Power gain  \[\frac{{{d}^{2}}x}{d{{t}^{2}}}+{{\omega }^{2}}x=0\] \[\Rightarrow \]   \[a=\frac{{{d}^{2}}x}{d{{t}^{2}}}=-{{\omega }^{2}}x\]


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