On 09/11/2014 18:07, Lostgallifreyan wrote:
Jeff wrote in :

E cross H in mathematical terms.


'Cross product' of E and H? As in, related to 'dot product'? If so that might
be my wau in to understanding Maxwell, I've used dot product before,
translated myself to find intersections of lines, and saw cross product
closely related, documented pretty much beside it a couple of times.




A cross product of two vectors is a third vector orthogonal to the first
two. In the case of the EM wave, the E and H vectors are orthogonal so
the cross product is in the third dimension, the direction of propagation.

A dot product is a scalar quantity, ie it has magnitude but no
direction. As you say, it is used to find where lines, represented as
vectors, intersect.