A charge q is uniformly distributed along the periphery of a non conducting uniform circular disc pivoted at its centre in a vertical plane and can freely rotate about a horizontal axis passing through its centre. A cylindrical region with its axis passing through the centre of the disc has a varying magnetic field B = kt as shown in the adjacent figure. wrapped over the disc as shown and remains stationary, then

Options

A. `m=(kqR)/(2g)`
B. `m=(2kqR)/(2g)`
C. Induced electric field at the centre of the disc, E=kR/2
D. Induced electric field at all points on the periphery of the disc , E=2kR

Answer

A