Em Waves Question 104
Question: An electromagnetic wave of frequency $ v=3.0MHz $ passes from vacuum into a dielectric medium with permittivity $ \in ,=4.0 $ . Then
Options:
A) wavelength is halved and frequency remains unchanged
B) wavelength is doubled and frequency becomes half
C) wavelength is doubled and the frequency remains unchanged
D) wavelength and frequency both remain unchanged.
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Frequency remains constant during refraction $ v _{med}=\frac{1}{\sqrt{{\mu _{0}}{\in _{0}}\times 4}}=\frac{c}{2} $
$ \frac{{\lambda _{med}}}{{\lambda _{air}}}=\frac{v _{med}}{v _{air}}=\frac{c/2}{c}=\frac{1}{2} $
$ \
Therefore $ wavelength is halved and frequency remains unchanged.
BETA
