Q 12-08-021NEETJEE MainMedium
The electric field of a plane EM wave is $E_y = 30\sin(2 \times 10^{7}t - kx)$ V/m. The wave number $k$ and wavelength are
Answer: (B) $\dfrac{1}{15}\ \text{m}^{-1}$ and $30\pi$ m
$k = \dfrac{\omega}{c} = \dfrac{2 \times 10^7}{3 \times 10^8} = \dfrac{1}{15}\ \text{m}^{-1}$, so $\lambda = \dfrac{2\pi}{k} = 30\pi \approx 94$ m.
Solution by Sreeraj P, M.Sc Physics