Suppose that the Earth's magnetic field (BE) in a given region is parallel to Earth’s surface, pointing north. A metal cable of length l (measured in meter) attached to a space station stretches radially outwards. If the cable is made to move eastward around Earth with a speed v, which end of the cable should turn positive, the lower end or the upper end?
a. In fact charges are developed across the length
b. Induced potential differennce depends neither on the speed of cable, nor on Earth's magnetic field.
c. The lower end
d. The upper end