Early simple electric generators

It's a metal disk with free, mobile electrons. As the free electrons revolve with the disk, they feel a q(vxB) Lorentz force on them due to the magnetic field they pass through (where q=electron charge, v=velocity, and B=magnetic field). Use the right-hand rule to determine the direction of the cross-product. The v-vector points approximately into the page, while the B-field points from the N-pole to the S-pole, so the right-hand rule gives vxB as pointing downward. But since the q, the electron charge, is negative, the q(vxB) vector points upward. So the electrons move from point Y, then through the disk to point X, through the light bulb (or "globe"), and back to point Y (i.e., counter-clockwise through the circuit shown). But electrons are negatively charged, so the current flow is actually in the opposite direction (i.e., clockwise). Therefore, the current flows from point Y (and through the "globe") to point X, which is answer (B). (P.S.: For the purposes of this problem of determining the direction of the current, you could have simply regarded the current carrying particles as being positively charged. Doing that would have also given you the right answer for the current direction but with fewer steps.)