A steel rod of length 40 cm and mass 0.20 kg is placed in a uniform magnetic field of 0.25 T so that the rod makes an angle of 30° with the direction of the field.
(a) Find the current required in the rod so that the magnetic force exactly balances its weight and the rod is in equilibrium.
(b) Keeping the current found in part (a) unchanged, the rod is slowly rotated until it becomes perpendicular to the magnetic field. Calculate the magnitude of the magnetic force on the rod in this new position and state whether the rod will accelerate upward or downward at the moment it reaches the perpendicular orientation. Explain your answer briefly.