A straight conductor of length 0.30m carrying a current of 8A is placed perpendicular to a uniform magnetic field of 0.40T. The conductor is then rotated about its own axis until the magnetic force acting on it becomes exactly one-half of its initial value. Through how many degrees has the conductor been rotated?
a) 45∘
b) 60∘
c) 120∘
d) 30∘