A particle of charge `Q` moving with kinetic energy `K` enters a zone of uniform magnetic field `B` along normal to `A_(1)B_(1)` as shown satisfying the condition `dgt(2K)/(QvB)` where `v` is the velocity of the particle .What will be tha angle of deflection in crossing the field at the centra of the curve followed by the particle in the field, if `K=QvBb` ? (`b`=radius of the circle in which the particle rotates)