BCECE Engineering BCECE Engineering Solved Paper-2002

  • question_answer
    The transfer ratio \[\] of a transistor is 50. The input resistance of the transistor when used in the common-emitter configuration is 1 \[\Omega \]. The peak value of the collector AC current for an AC input voltage of 0.01 V, is:

    A)  500 \[\text{A}\]              

    B)         0.25\[\text{A}\]

    C)  0.01 \[\text{A}\]             

    D)         100 \[\text{A}\]

    Correct Answer: A

    Solution :

    From the relation \[V=i\,R\] We have, \[V=0.01\,volt,\,R=1000\,\Omega \] \[\therefore \]  \[\Delta {{i}_{B}}=\frac{V}{R}=\frac{0.01}{1000}={{10}^{-5}}A\] Also from definition of AC current gain, \[\beta \]is the ratio of change in collector current to change in base current at a constant collector to emitter voltage. That is                                 \[\beta =\frac{\Delta {{i}_{C}}}{\Delta {{i}_{B}}}\]             \[\Rightarrow \]   \[\Delta {{i}_{C}}=\beta \Delta {{i}_{B}}\]\[=50\times {{10}^{-5}}=500\,\mu A\]


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