A movable conducting wire of length L moves along conducting rails at constant velocity i = vj, as shown in the figure. A resistor R is connected to the rails. The wire resistance is negligible. A uniform magnetic field B = (B. + ax/L) acts vertically %3D downward, in -z direciton ((B, and a are arbitrary positive constants). Find the induced emf and write which point is at higher electric potential, a or b. (6 pts) a y a. vL(B, + aL/2), point b b. v(B,L+ a), point a vL(B, + aL)/2, point a C. d. vL(2B, + a)/2, point b . v(B,L + ax), point b R.