\(\Rightarrow \mathrm{B}=2 \times 10^{-7}\)
\(\text { Also } \mathrm{C}=\mathrm{f} \lambda\)
\(\Rightarrow 3 \times 10^8=\mathrm{f} \times 4 \times 10^{-3}\)
\(\Rightarrow \mathrm{f}=\frac{3}{4} \times 10^{11}\)
\(\Rightarrow \omega=2 \pi \mathrm{f}=\frac{3}{4} \times 2 \pi \times 10^{11}\)
\(\Rightarrow \omega=\frac{\pi}{2} \times 10^3 \mathrm{C}\)
\(\Rightarrow \quad \text { Electric field } \Rightarrow \mathrm{y} \text { direction }\)
\(\text { Propagation } \Rightarrow \mathrm{x} \text { direction }\)
\(\text { Magnetic field } \Rightarrow z \text {-direction }\)
[$\left.\varepsilon_{0}=8.85 \times 10^{-12} \,{F} / {m}\right]$