\(E=10 \cos \left(10^{7} t+k x\right).........(i)\)

Comparing it with standard equation of e.m. wave,

\(E=E_{0} \cos (\omega t+k x).........(ii)\)

Amplitude \(E_{0}=10\, \mathrm{V} / \mathrm{m}\) and \(\omega=10^{7} \,\mathrm{rad} / \mathrm{s}\)

\(\because \quad c=u \lambda=\frac{\omega \lambda}{2 \pi}\)

or \(\quad \lambda=\frac{2 \pi c}{\omega}=\frac{2 \pi \times 3 \times 10^{8}}{10^{7}}=188.4 \,\mathrm{m}\)

Also, \(c=\frac{\omega}{k}\) or \(k=\frac{\omega}{c}=\frac{10^{7}}{3 \times 10^{8}}=0.033\)

The wave is propagating along \(y\) direction.