1 10
T
3 10 m/s
E
B
c
=
=
=
×
×
To find the direction, we note that E is along y-direction and the
wave propagates along x-axis Therefore, B should be in a direction
perpendicular to both x- and y-axes Using vector algebra, E × B should
be along  x-direction Since, (+ ˆj ) × (+ ˆk ) = ˆi , B is along the z-direction