NEET Sample Paper NEET Sample Test Paper-72

  • question_answer
    Consider an n-p-n transistor amplifier in common-emitter configuration. The current gain of the transistor is 100. If the collector current changes by 1 mA, what will be the change in emitter current?

    A) 1.1 mA             

    B) 1.01 mA

    C) 0.01 mA                       

    D) 10 mA

    Correct Answer: B

    Solution :

    Current gain is defined as ratio of collector current to base current. \[Current\,\,gain=\frac{change\,\,in\,\,collector\,\,current}{change\,\,in\,\,ba\operatorname{se}\,\,current}\]  \[\beta =\frac{\Delta {{i}_{C}}}{\Delta {{i}_{B}}}\] Also \[{{i}_{E}}={{i}_{B}}+{{i}_{C}}\,\,\,\,\Rightarrow \,\,\Delta {{i}_{E}}=\Delta \,{{i}_{B}}+\Delta {{i}_{C}}\] \[\beta =\frac{\Delta {{i}_{C}}}{\Delta {{i}_{E}}-\Delta {{i}_{C}}}\] Given, \[\beta \,\,=\,\,100,\,\,\Delta {{i}_{C}}=1mA\] \[\therefore \,\,\,\,\,\,100=\frac{1}{\Delta {{i}_{E}}-1}\] \[\Delta {{i}_{E}}-1=\frac{1}{100}=0.01\] \[{{\Delta }_{i}}E=1+0.01=1.01\,\,mA\]


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