JEE Main & Advanced Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव Question Bank Biot-savart's Law and Amperes Law

  • question_answer
    There are 50 turns of a wire in every cm length of a long solenoid. If 4 ampere current is flowing in the solenoid, the approximate value of magnetic field along its axis at an internal point and at one end will be respectively [MP PET 1996]

    A)            \[12.6\times {{10}^{-3}}\,Weber/{{m}^{2}},\ 6.3\times {{10}^{-3}}\,Weber/{{m}^{2}}\]

    B)            \[12.6\times {{10}^{-3}}\,Weber/{{m}^{2}},\ 25.1\times {{10}^{-3}}\,Weber/{{m}^{2}}\]

    C)            \[25.1\times {{10}^{-3}}\,Weber/{{m}^{2}},\ 6.3\times {{10}^{-3}}\,Weber/{{m}^{2}}\]

    D)            \[25.1\times {{10}^{-5}}\,Weber/{{m}^{2}},\ 6.3\times {{10}^{-5}}\,Weber/{{m}^{2}}\]

    Correct Answer: C

    Solution :

                       The magnetic field in the solenoid along its axis (i) At an internal point\[={{\mu }_{o}}ni\] \[=4\pi \times {{10}^{-7}}\times 5000\times 4=25.1\times {{10}^{-3}}Wb/{{m}^{2}}\] \[(\text{Here }n=50\,turns/cm=5000\,turns/m)\] (ii) At one end \[{{B}_{end}}=\frac{1}{2}{{B}_{in}}=\frac{{{\mu }_{0}}ni}{2}=\frac{25.1\times {{10}^{-3}}}{2}\]\[=12.6\times {{10}^{-3}}Wb/{{m}^{2}}\]


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