A rectilinear homogeneous conductor OA of mass 12 g and of length 36cm hangs freely from its upper end O while its lower end A slightly touches the surface of the mercury. Terminals C and D are connected to a generator which supplies a current 7.4A. A horizontal magnetic field is made to act on a part of the wire. The direction of B is directed towards the reader , it is observed that conductor OA is shifted from its vertical position of equilibrium by an angle 5º30' .
Precise the polarity of terminals C and D.
Thx