JEE Main & Advanced JEE Main Paper (Held On 9 April 2017)

  • question_answer
    The current gain of a common emitter amplifier is 69. If the emitter current is 7.0 mA, collector current is - [JEE Online 09-04-2017]

    A)  69 mA                 

    B)  0.69 mA

    C)  6.9 mA                                

    D)  9.6 mA

    Correct Answer: C

    Solution :

                    \[\beta =69=\frac{{{I}_{C}}}{{{I}_{B}}}\]                 \[\alpha =\frac{\beta }{1+\beta }\,=\frac{69}{70}=\frac{{{I}_{C}}}{{{I}_{E}}}\]                 \[{{I}_{C}}={{I}_{E}}\times \frac{69}{70}\]                 \[=\frac{69}{70}\times 7\]                 \[=6.9\,mA\]


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