I can't find an answer for this anywhere, I'm getting desperate for help, so I hope someone is willing.
From my understanding, in an electromagnetic wave, the direction of propagation is perpendicular to the magnetic and electric fields, which are perpendicular to eachother as well.
for example,
E x B = direction of propagation
If given an Electric field equation of a EM wave, like e.g E = E_o x e^(ky-wt)
and nothing else, how do I know whether the direction of the wave is in the x or z direction? as both are perpendicular.
I have to answer a multiple choice where there is a choice for all 3 directions. I'm not given the magnetic field, only that equation above.
>>7931881
Shouldn't that be i(ky-wt)
>>7931885
Yeah sorry I made a typo.
bump
someone please
>muh plane wave
>>7931881
E is a vector. The starting conditions /should/ include its direction.
Poynting vector
https://en.wikipedia.org/wiki/Poynting_vector
Given an electric field, you can find corresponding magnetic field by Maxwell's eqs.
Now you have those both fields, you can calculate the Poynting vector.
>>7931881
Keep in mind that is only true for free-space plane-wave approximation. If the wave propagates inside a medium or a waveguide, only certain parts might be perpendicular to the direction of propagation (traverse modes).
Your equation says the E vector is in the x direction. The argument in the exponential shows that the E field changes along the y direction, so that's the direction of propogation. Also, complex-valued equations disgust me.
>>7931881
Consider a particle moving with trajectory y=vt. If the particle has the same velocity as the wave, then the field seen by the particle should be constant. What v will make ky-wt constant?
