Physics - EM Waves Question with Solution | TestHub

The equation of electric field is given in the question, $E=50\sin \left(500x-10\times {10}^{10}t\right) \mathrm{V} {\mathrm{m}}^{-1}$ now compare it the equation of electric field in an electromagnetic wave, $E=E_0\sin \left(kx-\omega t\right) \mathrm{V} {\mathrm{m}}^{-1}$

$\Rightarrow \omega ={10}^{10} \mathrm{rad} {\mathrm{s}}^{-1}$ and, $k=50 {\mathrm{m}}^{-1}$, so the velocity of electromagnetic waves is, $v=\frac{\omega }{k}=\frac{{10}^{10}}{50}=2\times {10}^8=\frac{2}{3}c$.