An electromagnetic wave of frequency n = 3.0 MHz passes from vacuum into a dielectric medium with permittivity ε = 4.0. Then
Answer & explanation
Correct answer: option 1
Velocity of light, v = $\frac{1}{\sqrt{\mu_0 \varepsilon_0 \varepsilon_{r}}}=\frac{1}{\sqrt{\mu_0 \varepsilon_0 . 4}}=\frac{c}{2}$
v remains constant hence
$\lambda=\frac{v}{v}=\frac{\lambda_0}{2}$ since $v=\frac{c}{2}$
∴ wavelength is halved and frequency remains unchanged.