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MGIMS WARDHA MGIMS WARDHA Solved Paper-2006

  • question_answer
    A wire carrying current\[I\] and other carrying \[2I\]in the same direction produce a magnetic field B at the mid-point. What will be the field when \[2I\] wire is switched of?

    A) B / 2                                      

    B)  2B

    C) B                                            

    D) 4B

    Correct Answer: C

    Solution :

    When currents in both the wires are in same direction, then magnetic field at the centre \[B={{B}_{2}}-{{B}_{1}}=\frac{{{\mu }_{0}}(2I)}{2\pi (r/2)}-\frac{{{\mu }_{0}}I}{2\pi (r/2)}\]                                 \[=\frac{{{\mu }_{0}}I}{\pi r}\] When\[2I\]wire is switched off, then magnetic field at the centre \[B'=\frac{{{\mu }_{0}}I}{2\pi (r/2)}=\frac{{{\mu }_{0}}I}{\pi r}=B\]


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