Physics - EM Waves Question with Solution | TestHub

Velocity of electromagnetic wave in vacuum. $$C=\frac{1}{\sqrt{{\mu }_0{\epsilon }_0}}=V_{\mathrm{vacum}}$$ Velocity of electromagnetic wave in medium $$V_{med}=\frac{1}{\sqrt{{\mu }_0{\mu }_0{\epsilon }_0{c}_{nr}}}=\frac{\mathrm{C}}{\sqrt{{\mu }_r{\epsilon }_r}}$$ ${\mu }_0$ and ${\epsilon }_0$ is in vacuum and $\mu \mathrm{r}{\epsilon }_0$ is in medium. For dielectric medium $r=1$ $$\begin{array}{rl}& \therefore V_{\text{med }}=\frac{C}{\sqrt{{\epsilon }_r}}\text{ Given }{\epsilon }_0=4\\ & \therefore V_{\text{med }}=\frac{C}{\sqrt{4}}=\frac{\mathrm{C}}{2}\end{array}$$ $\therefore$ Wavelength of the wave in medium ${\lambda }_{\text{med }}=\frac{V_{\text{med }}}{V}=\frac{C}{2V}=$ $\frac{{\lambda }_{\text{vacum }}}{2}$