JEE Main & Advanced Physics Current Electricity, Charging & Discharging Of Capacitors / वर्तमान बिजली, चार्ज और कैपेसिटर का निर Question Bank Self Evaluation Test - Current Electricity

  • question_answer
    The total momentum of electrons in a straight wire of length 1000m carrying a current of 70A is closest to

    A) \[40\times {{10}^{-8}}N-\sec \]

    B) \[30\times {{10}^{-8}}N-\sec \]

    C) \[50\times {{10}^{-8}}N-\sec \]

    D) \[70\times {{10}^{-8}}N-\sec \]

    Correct Answer: A

    Solution :

    [a] No. of electron in the wire \[=nA\ell \,(n={{e}^{-}}\text{density})\] and momentum \[=n\,eA\,{{v}_{d}}=\frac{\ell {{m}_{e}}}{e}=\frac{I\,\ell {{m}_{e}}}{e}\] \[=\frac{70\times 1000}{1.6\times {{10}^{-19}}}\times 9.1\times {{10}^{-31}}=40\times {{10}^{-8}}N-\sec \]


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