A wire, shown in Figure P17.48, moves downward perpendicular to a magnetic field. (a) In...

A wire, shown in Figure P17.48, moves downward perpendicular to a magnetic field. (a) In what direction will the electrons in the wire move? (b) After the electrons are forced in one direction, leaving positive charges behind, an field and potential difference ΔV develop from one end of the wire to the other. The electrons no longer move, since the electric and magnetic forces exerted on them balance. Show that this happens when the potential difference from one end of the wire to the other is ΔV = vLB, where v is the speed of the wire, L is its length, and B is the magnitude of the magnetic field. Describe two real-world situations where this phenomenon might occur.