(a) The motion is going in the opposite direction of the y-axis. To put it another way, along -j.

(b) The given equation is compared with the equation and we get,

$E=E_{0} \cos (k y+\omega t)$

$\Rightarrow \mathrm{k}=1.8 \mathrm{rad} / \mathrm{s}$

$\omega=5.4 \times 10^{6} \mathrm{rad} / \mathrm{s}$

$\lambda=2 \pi / \mathrm{k}=(2 \times 3.14) / 1.8=3.492 \mathrm{~m}$