Poynting Vector: a Plane EM Wave in 3D

A plane electromagnetic wave shown in 3D: the electric field E (red/blue) and magnetic field B (orange) oscillate in phase, perpendicular to each other and to the direction of travel, with |E| = c|B|. The white arrows are the Poynting vector S = E x B / mu0, which points along the propagation axis and carries the wave's energy at speed c, and ghost wavefront planes march forward at c. Switching modes shows linear polarization, circular (the E tip traces a helix), elliptical, and a standing wave formed by two counter-propagating waves with fixed nodes; drag to orbit and see the field geometry from any angle.