JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2008

  • question_answer
        A solenoid 1.5 m long and 0.4 cm in diameter possesses 10 turns per cm length. A current of 5 A falls through it. The magnetic field at the axis inside the solenoid is

    A)  \[2\pi \times {{10}^{-3}}T\]                        

    B)  \[2\pi \times {{10}^{-5}}T\]

    C)  \[2\pi \times {{10}^{-2}}T\]                        

    D)  \[2\pi \times {{10}^{-3}}T\]

    Correct Answer: A

    Solution :

                    Magnetic field at the axis inside the solenoid \[B={{\mu }_{0}}ni\] Here,\[n=10\text{ }turns/cm=1000\text{ }turns/m,i=5A\] \[\therefore \]  \[B=4\pi \times {{10}^{-7}}\times 1000\times 5\]                 \[=2\pi \times {{10}^{-3}}T\]


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