NEET Physics Semiconducting Devices NEET PYQ-Semiconducting Devices

  • question_answer
                The transfer ratio \[\beta \] of a transistor is 50. The input resistance of the transistor when used in the common emitter configuration is \[1\,k\,\Omega \]. The peak value of the collector AC current for an AC input voltage of 0.01 V peak is:                                                                                                                                              [AIPMT 1998]

    A)  \[100\,\mu A\]  

    B)       \[0.01\,mA\]     

    C)  \[0.25\,mA\]     

    D)       \[500\,\mu A\]

    Correct Answer: D

    Solution :

    Key Idea: In common emitter configuration of a transistor, the input current is a base current. Input current
                            \[{{i}_{B}}=\frac{\Delta \,{{V}_{B}}}{{{R}_{B}}}\]
                            \[=\frac{0.01}{1000}={{10}^{-5}}\,A\]
                Also current gain
                            \[\beta =\frac{{{i}_{C}}}{{{i}_{B}}}\]
                \[\therefore \]      \[{{i}_{C}}=\beta {{i}_{B}}=50\times {{10}^{-5}}\,A\]
                            \[=500\times {{10}^{-6}}\,A=500\,\mu A\]


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