A conducting rod of length ? [cross-section is shown] and mass m is moving down on a smooth inclined plane of inclination `theta` with constant speed `v` . A vertically upward mag. field `vecB` exists in upward direction. The magnitude of mag. field `vecB` is .........................
Options:
(a) `(mg sintheta)/(Il)`
(b) `(mg costheta)/(Il)`
(c) `(mg tantheta)/(Il)`
(d) `(mg)/(sinthetaIl)`