JCECE Engineering JCECE Engineering Solved Paper-2010

  • question_answer
    The contribution in the total current flowing through a semiconductor due to electrons and holes are \[\frac{3}{4}\] and \[\frac{1}{4}\] respectively. If the drift velocity of electrons is \[\frac{5}{2}\] times that of holes at this temperature, then the ratio of concentration of electrons and holes is

    A) \[6:5\]                                  

    B) \[5:6\]

    C) \[3:2\]                                  

    D)  \[2:3\]

    Correct Answer: A

    Solution :

    As we know, current density\[J=nqv\] \[\Rightarrow \]               \[{{J}_{e}}={{n}_{e}}q{{v}_{e}}\] and        \[{{J}_{h}}={{n}_{h}}q{{v}_{h}}\] \[\Rightarrow \]               \[\frac{{{J}_{e}}}{{{J}_{h}}}=\frac{{{n}_{e}}}{{{n}_{h}}}\times \frac{{{v}_{e}}}{{{v}_{h}}}\] \[\Rightarrow \]               \[\frac{3/4}{1/4}=\frac{{{n}_{e}}}{{{n}_{h}}}\times \frac{5}{2}\] \[\Rightarrow \]               \[\frac{{{n}_{e}}}{{{n}_{h}}}=\frac{6}{5}\]


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