12th Class Physics Sample Paper Physics Sample Paper-2

  • question_answer
    Obtain with the help of necessary diagram, the expression for the magnetic field in the open space interior of a toroid carrying current.


    Toroid is a hollow circular ring on which a large number of insulated turns of a metallic wire are closely wound. The direction of the magnetic field at a point P is given by tangent to the magnetic field line at that point. Let B is the magnetic field in (he open space interior to the toroid. Considering a loop coplanar with toroid of radius x such that x < R (radius of toroid) as shown in the figure. Applying Ampere's circuital law over loop, we have \[\oint{B\cdot dl=}{{\mu }_{0}}\times \]Current passes on the loop But no current passes through the loop. \[\therefore \]      \[\oint{B\cdot dl={{\mu }_{0}}\times 0}=0\Rightarrow B=0\] Thus, the magnetic field exist in the open space interior of toroid is zero.

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