Consider the system pictured in the figure below. A 13.5-cm horizontal wire of mass 16.1 g is placed between two thin, vertical conductors, and a uniform magnetic field acts perpendicular to the page. The wire is free to move vertically without friction on the two vertical conductors. When a 5.20-A current is directed as shown in the figure, the horizontal wire moves upward at constant velocity in the presence of gravity.
(a) What forces act on the horizontal wire? (Select all that apply.)
(b) Under what condition is the wire able to move upward at constant velocity?
(c) Find the magnitude and direction of the minimum magnetic field required to move the wire at constant speed.
(d) What happens if the magnetic field exceeds this minimum value?