Question

An electromagnetic wave of frequency `v=3.0 MHz` passes from vacuum into a dielectric medium with permittivity `epsilon=4.0`. Then
A. wavelength is doubled and the frequency remains unchainged
B. wavelength is doubled and frequency becomes half
C. wavelength is halved and frequency remains unchanged
D. wavelength and frequency both remain unchanged

Answer 1

Correct Answer - C

Answer 2

 \(v_{med}=\frac{1}{\sqrt{\mu_0\varepsilon_0\times 4}}\)

\(v_{med}=\frac{c}{2}\)

\(\cfrac{\lambda_{med}}{\lambda_{air}}=\cfrac{v_{med}}{v_{air}}\)

\(\cfrac{\lambda_{med}}{\lambda_{air}}=\cfrac{\frac c2}{c} \Rightarrow \frac12\)

Wavelength will be Halved.