A thin non conducting disc of mass M = 2 kg, charge `Q = 2 xx 10^(2-) C` and radius `R = (1)/(6)m` is placed on a frictionless horizontal plane with its centre at the origin of the coordinate system. A non- uniform, radial magnetic field `vecB = B_(0) hat(r)` is exists in space, where `B_(0)= 10 T` and `hat(r)` is a unit vector in the radially outward direction. The disc is set in motion with an angular velocity `omega = x xx 10^(2)" rad s"^(-1)`, about an axis passing through its centre and perpendicular to its plane, as shown in the figure. At what value of x, the disc will lift off from the surface.

Answer

9