The electric field part of an electromagnetic wave in a medium is represented by $E_{x}=0$; $E_{y}=2.5 NC^{-1} \times \cos \left[\left(2 \pi \times 10^6 rads^{-1}\right) t-\left(\pi \times 10^{-2} radm^{-1}\right) x\right] ; E_{z}=0$. The wave is:
Answer & explanation
Correct answer: option 2
Given, $E_x=0$
$E_{y}=2.5 NC^{-1} \times \cos \left[\left(2 \pi \times 10^6 rads^{-1}\right) t-\left(\pi \times 10^{-2} radm^{-1}\right) x\right], E_{z}=0$. This shows that the wave is propagating along x – axis. Comparing the given equation with $E=E_0 \cos (\omega t - kx)$, we have $\omega=2 \pi \times 10^6$
or $2 \pi v=2 \pi \times 10^6 \Rightarrow v=10^6 Hz$
and $\frac{2 \pi}{\lambda}=k=\pi \times 10^{-2} \Rightarrow \lambda=\frac{2 \pi}{\pi \times 10^{-2}}$ = 200 m