"This is partially correct, ac does change direction, but the EM wave does not." The fact that voltage/signal flows outside the conductor, as a wave, and always toward the load, doesn't fit their 1800's science based theories of AC electricity. They're still trying to shove electrons through conductors (waveguides). https://en.wikipedia.org/wiki/Speed_of_electricity Note what's stated under 'Electric Drift', regarding AC and electrons. Save your keystrokes, as any modern science/theory will be categorically dismissed, by the Naysayer Doctrine adherents.