Erm, i think that's what i did. i knew that the dot products would give 0 as each one is along a different axis. Thanks for the reply btw, its good to know that I'm going along the right line.
3 (a) ii) A time-dependent electric field in vacuum is given by
⃗E= E0(0, 0, sin(ky − ωt))
where E0 is a constant.
Derive an expression for the corresponding magnetic field ⃗B. [7]
Using curl E=-dB/dt
I end up with B=(E0/c)sin(ky-wt)
Show that both ⃗E and ⃗B are perpendicular to the wave...