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NEET AIPMT SOLVED PAPER SCREENING 2006

  • question_answer
                    A transistor is operated in common emitter configuration at constant collector voltage \[{{V}_{c}}=1.5\,\,V\] such that a change in the base current from 100\[\mu \]A to 150\[\mu \]A produces a change in the collector current from 5 mA to 10 mA. The current gain \[(\beta )\] is:                                                                                                                      

    A)                  67         

    B)                  75                         

    C)                  100    

    D)                  50

    Correct Answer: C

    Solution :

                    AC current gain \[\beta \] is defined as the ratio of the collector to the base current at constant collector voltage,                 \[\beta =\left( \frac{\Delta {{i}_{C}}}{\Delta {{i}_{B}}} \right){{v}_{c}}\]                 Given,   \[\Delta {{i}_{C}}=10\,mA-5\,mA=5\,mA\]                 \[\Delta {{i}_{B}}=150\,\mu A-100\,\mu A=50\,\mu A\]                 \[\therefore \]  \[\beta =\frac{5\,mA}{50\times {{10}^{-3}}\,mA}=100\]                 Note:    In common emitter amplifier, the output voltage signal is \[{{180}^{o}}\] out of phase with the input voltage signal.


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