Consider a uniform metal disk rotating 1hrough a perpendicular magnetic field ii, as shown in Fig. 29.19a. The disk has mass m, radius R, and thickness t, is made of a material with resistivity p, and is rotating clockwise in Fig. 29.19a with angular speed Cd. The magnetic field is directed into the plane of the disk. Suppose that the region to which the magnetic field is confined is not circular, as shown in Fig. 29.19a, but is a small square with sides of length L (L « R) centered a distance d from the point 0 (the center of the disk). The sides of this square are horizontal and vertical in Fig. 29.19a.
(a) Show that the current induced within the square is approximately equal to I = wdBLt/ p. In which direction does this current flow?