MGIMS WARDHA MGIMS WARDHA Solved Paper-2006

  • question_answer
    What is the drift velocity of electrons if the current flowing through a copper wire of 1 mm diameter is 1.1 A- Assume that each atom of copper contributes one electron : (Given : density of Cu = 9 g/cm3 and atomic weight of Cu = 63)

    A) 0.3 mm/s            

    B) 0.5 mm/s

    C) 0.1 mm/s            

    D) 0.2 mm/s

    Correct Answer: C

    Solution :

    Number of atoms in 63 g of copper = Avogadro number \[=6\times {{10}^{23}}\] Volume of 63 g of copper \[=\frac{63}{density}=\frac{63}{9}\] \[=7\text{ }c{{m}^{3}}\] \[n=\frac{6.02\times {{10}^{23}}}{7}per\,c{{m}^{3}}\]                 \[=\frac{6.02\times {{10}^{29}}}{7}per\,c{{m}^{3}}\] Area      \[A=\pi {{r}^{2}}\] \[=\pi {{(0.5\times {{10}^{-3}})}^{2}}{{m}^{2}}\] Drift velocity is\[v=\frac{1}{neA}\] \[=0.1\times {{10}^{-3}}m/s\] \[=0.1\text{ }mm/s\]


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