There are a few good youtube videos that calculate c from Maxwell's Equations, but the jist of it still hasn't gelled with me. In other words, I'm still scratching my head. I wonder if anyone could (without using math) explain to me how a velocity can be calculated from magnetic and electric field relationships. I think it has something to do with the change of the ratio of the field strengths of the two, but can you explain this so it makes sense? I recognize that in an electromagnetic wave when the mag field gets stronger the electric field gets weaker and these two oscillate, but how can a velocity be calculated from this? In other words, what is the logic behind this? Thanks.