Comment by kalid

Great point! That's something I didn't make clear enough in the diagram, and a 2nd misconception I had until a month ago too :).

Yes, exactly as you say, the total energy is the same but the orientation and amplitude of the field differs. I think the trouble is showing another dimension without resorting to the y-axis which is too easily confused with a path to travel (especially a sine wave, which is usually shown in the context of "height on a circle" or somesuch).

Red and blue colors may be better -- bright red to bright blue, showing which way the field is pointing at that time. Black and white are too easily confused with dim and bright (and a light wave never goes "off").

The original diagrams were made years ago and I should update the colors. Definitely appreciate the feedback!