• # 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:                                                                                                                              A)                 $100\,\mu A$                  B)                 $0.01\,mA$                      C)                 $0.25\,mA$                      D)                 $500\,\mu A$

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                 $\beta =\frac{{{i}_{C}}}{{{i}_{B}}}$ $\therefore {{i}_{C}}=\beta {{i}_{B}}=50\times {{10}^{-5}}\,A$                 $=500\times {{10}^{-6}}\,A=500\,\mu A$