Regarding the original question:
If a light wave is moving forward, and the positive direction of
the electric field is up, is the positive direction of the magnetic
field to the right or the left? How can that be determined?
Can you provide a URL to a reliable web page which states the
right-hand rule which applies to electromagnetic radiation? I can
find the rule for currents in a conductor and the resulting force, but
the one page I found that has an illustration showing the directions
of the electric and magnetic fields in EM radiation appears to show
the positive direction of the magnetic field to the left, not the right.
Bottom of the page. I assume that the wave is travelling toward
positive X, away from the viewer.
http://www.ch.ic.ac.uk/local/physical/mi_5.html
I note that this diagram uses a color scheme which is exactly opposite
the one that I use, and the planes of the electric and magnetic fields
are exactly opposite the positions I conventionally place them in. *
If the blue were the E field and the red were the B field, it would fit
the rule korjik stated: If k is forward and E is up then B is to the right.
-- Jeff, in Minneapolis
* Edit to correct: I was wrong about the planes of the E & B fields
being in the opposite positions from those I conventionally use. Since
you've probably never seen any diagram I've drawn of this, it makes
no difference anyhow.