JEE Main & Advanced Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर Question Bank Electric Conduction Ohms and Resistance

  • question_answer
    Every atom makes one free electron in copper. If 1.1 ampere current is flowing in the wire of copper having 1 mm diameter, then the drift velocity (approx.) will be (Density of copper \[=9\times {{10}^{3}}\,kg\,{{m}^{-3}}\] and atomic weight = 63) [CPMT 1989]

    A)                    \[0.3\,mm/\sec \]      

    B)            \[0.1\,mm/\sec \]

    C)                    \[0.2\,mm/\sec \]      

    D)                    \[0.2\,cm/\sec \]

    Correct Answer: B

    Solution :

                 Density of \[Cu=9\times {{10}^{3}}kg/{{m}^{3}}\] (mass of 1 m3 of Cu) \[6.0\times {{10}^{23}}\] atoms has a mass \[=\text{ }63\times {{10}^{3}}kg\] \ Number of electrons per \[{{m}^{3}}\]are \[=\frac{6.0\times {{10}^{23}}}{63\times {{10}^{-3}}}\times 9\times {{10}^{3}}=8.5\times {{10}^{28}}\] Now drift velocity \[={{v}_{d}}=\frac{i}{neA}\] \[=\frac{1.1}{8.5\times {{10}^{28}}\times 1.6\times {{10}^{-19}}\times \pi \times {{(0.5\times {{10}^{-3}})}^{2}}}\] \[=0.1\times {{10}^{-3}}m\,/sec\]


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