 Electric-cross-magnetic-field drift

In uniform perpendicular electric and magnetic fields, a charged particle's guiding centre drifts with velocity ${\mathbf{v}}_D=\mathbf{E}\times \mathbf{B}/B^2$, independently of its charge and mass. For $\mathbf{E}=E{\mathbf{e}}_x$ and $\mathbf{B}=B{\mathbf{e}}_z$, this gives $v_y=-E/B$.