Write–Up–II
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 . 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 either in the clockwise direction or in the anti-clockwise direction.
A constant horizontal magnetic field B is present throughout the space as shown in the figure. (Assume is large enough to help rolling motion)
Question
The minimum value of for which the rolling motion is possible, is