A toroid with thick windings of N turns has inner and outer radii R1 and R2 respectively. If it carries certain steady current I, the variation of the magnetic field due to the toroid with radial distance is correctly graphed in
The Correct Option is D
Solution and Explanation
A toroid, regardless of winding thickness, has a zero magnetic field outside its structure (both inside the toroidal cavity and outside the outer radius).
The windings themselves create the field, but they are confined within the toroid structure between R1 and R2.
Therefore, the correct graphical representation shows a constant field (represented by the horizontal line) between R1 and R2, where the windings are, and zero elsewhere.
The correct answer is indeed (D): 
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