Direction of Electric Field in an Electromagnetic Wave

[spaghetti3451]

Homework Statement

If the magnetic field of a light wave oscillates parallel to a y axis and is given by $B_y = B_m\ sin(kz- \omega t)$,

(a) in what direction does the wave travel and

(b) parallel to which axis does the associated electric field oscillate?

Homework Equations

The Attempt at a Solution

(a) The wave is propagating in the $+ z$-direction because the form of the argument in the sinusoidal function.

(b) I'm having problem here.

 

[Simon Bridge]

(b) where are you having the problem?

 

[spaghetti3451]

I think I figured it out. :D

If the direction of propagation is given by $\overrightarrow(E) \times \overrightarrow(B)$, then shouldn't the direction of the electric field be in the $+ x$-direction.

 

[Simon Bridge]

That's the one - well done.
Just remember that the E and B fields are perpendicular.

LaTeX note: use curly brackets to enclose what you operate on, but not needed if there is only on letter following the command.
Thus \vec E \times \vec B gets you $\vec E \times \vec B$

 

[spaghetti3451]

Thank you! :)