A person wants to roll a solid non-conducting spherical ball of mass `m` and radius `r` on a surface whose coefficient of static friction is `mu`. He placed the ball on the surface wrapped with `n` turns of closely packed conducting coils of negligible mass at the diameter.
By some arrangement he is able to pass a current `i` through the coils in anti-clockwise direction when viewed downwards from point `P`. A constant horizontal magnetic field `vecB` is present throughout the space along the positive `x` direction as shown in the figure. (Assume `mu` is large enough to help pure rolling motion and initially the plane of the coils is perpendicular to the `y`-axs)
If current `i` is passed through the coil then

Options

A. `sqrt(10/7 (piniB)/m sin theta)`
B. `sqrt(5/14 (piniB)/m sin theta)`
C. `sqrt(5/14 (piniB)/m costheta)`
D. `sqrt(5/7 (piniB)/m sintheta)`

Explanation

NA